# GCN_circulars

GRB_name: GRB210827A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30733
SUBJECT: GRB 210827A: Swift ToO observations
DATE:    21/08/27 22:02:28 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a ToO observation of the Swift/BAT-GUANO GRB 210827A. 
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021461

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Swift/BAT-GUANO event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a 
GCN Circular after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB210827A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30734
SUBJECT: GRB 210827A: Swift-XRT observations
DATE:    21/08/28 08:58:36 GMT
FROM:    Paolo D'Avanzo at INAF - OAB  <paolo.davanzo@inaf.it>

J. D. Gropp (PSU), J.A. Kennea (PSU), A.P. Beardmore (U. Leicester),
J.P. Osborne (U. Leicester), T. Sbarrato (INAF-OAB), P. D'Avanzo
(INAF-OAB), M.G. Bernardini (INAF-OAB), A. Tohuvavohu (U. Toronto) and
P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Swift/BAT-GUANO-detected burst GRB 210827A (James DeLaunay et al. GCN
Circ. 30732), collecting 2.3 ks of Photon Counting (PC) mode data
between T0+44.4 ks and T0+50.4 ks. 

One uncatalogued X-ray source has been detected consistent with being
within 296 arcsec of the Swift/BAT-GUANO position, it is below the RASS
limit and shows no definitive signs of fading. Therefore, at the
present time we cannot confirm this as the afterglow. Details of this
source are given below:

Source 3:
  RA (J2000):  174.9003  =  11:39:36.07
  Dec (J2000): +55.7239  =  +55:43:26.2
  Error: 3.8 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: 0.0103 +/- 0.0025 ct s^-1   
  Distance: 225 arcsec from Swift/BAT-GUANO position.
  Flux: (4.8 +/- 1.2)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Four uncatalogued sources were also detected too far from the GRB
position to be likely afterglow candidates.

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
https://www.swift.ac.uk/ToO_GRBs/00021461.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB210827B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30735
SUBJECT: Fermi GRB 210827B: Global MASTER-Net observations report 
DATE:    21/08/28 12:30:29 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev, O.Ershova 
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

V. Yurkov, A. Gabovich, Yu. Sergienko 
(Blagoveschensk Educational State University)




MASTER-Kislovodsk robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 210827B ( Fermi GBM team, GCN 30726) errorbox  24325 sec after notice time and 24337 sec after trigger time at 2021-08-27 16:55:53 UT, with upper limit up to  18.2 mag. Observations started at twilight.  The observations began at zenith distance = 69 deg. The sun  altitude  is -11.4 deg. 

The galactic latitude b = -32 deg., longitude l = 26 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1701427

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

   15633 | 2021-08-27 14:30:38 |             MASTER- | (20h 28m 55.00s , -19d 15m 45.0s) |   C |    20 | 15.2 |        
   16581 | 2021-08-27 14:46:27 |             MASTER- | (20h 28m 52.92s , -19d 12m 38.6s) |   C |    20 | 14.9 |        
   17531 | 2021-08-27 15:02:16 |             MASTER- | (20h 28m 53.96s , -19d 13m 34.5s) |   C |    20 | 15.0 |        
   18829 | 2021-08-27 15:23:55 |             MASTER- | (20h 31m 16.41s , -17d 19m 29.2s) |   C |    20 | 14.8 |        
   18829 | 2021-08-27 15:23:55 |             MASTER- | (20h 23m 01.74s , -18d 44m 06.1s) |   C |    20 | 13.7 |        
   19755 | 2021-08-27 15:39:20 |             MASTER- | (20h 31m 06.85s , -17d 19m 50.6s) |   C |    20 | 12.6 |        
   19755 | 2021-08-27 15:39:20 |             MASTER- | (20h 22m 54.22s , -18d 43m 23.5s) |   C |    20 | 13.5 |        
   20653 | 2021-08-27 15:54:19 |             MASTER- | (20h 31m 05.17s , -17d 20m 21.3s) |   C |    20 | 14.9 |        
   20653 | 2021-08-27 15:54:19 |             MASTER- | (20h 22m 55.05s , -18d 42m 04.8s) |   C |    20 | 13.2 |        
   24368 | 2021-08-27 16:55:53 |   MASTER-Kislovodsk | (20h 27m 37.06s , -17d 37m 30.7s) |   C |    60 | 16.9 |        
   24368 | 2021-08-27 16:55:53 |   MASTER-Kislovodsk | (20h 32m 08.17s , -18d 03m 02.3s) |   C |    60 | 17.1 |        
   24528 | 2021-08-27 16:58:34 |   MASTER-Kislovodsk | (20h 25m 24.24s , -19d 31m 47.6s) |   C |    60 | 17.0 |        
   24528 | 2021-08-27 16:58:34 |   MASTER-Kislovodsk | (20h 29m 57.78s , -19d 57m 21.8s) |   C |    60 | 17.4 |        
   25329 | 2021-08-27 17:11:55 |   MASTER-Kislovodsk | (20h 27m 35.57s , -17d 37m 16.0s) |   C |    60 | 17.3 |        
   25329 | 2021-08-27 17:11:55 |   MASTER-Kislovodsk | (20h 32m 08.08s , -18d 02m 47.5s) |   C |    60 | 17.9 |        
   25489 | 2021-08-27 17:14:35 |   MASTER-Kislovodsk | (20h 25m 19.62s , -19d 33m 12.5s) |   C |    60 | 17.3 |        
   25489 | 2021-08-27 17:14:35 |   MASTER-Kislovodsk | (20h 29m 54.59s , -19d 58m 46.9s) |   C |    60 | 17.9 |        
   26292 | 2021-08-27 17:27:57 |   MASTER-Kislovodsk | (20h 27m 38.37s , -17d 37m 26.2s) |   C |    60 | 17.4 |        
   26292 | 2021-08-27 17:27:57 |   MASTER-Kislovodsk | (20h 32m 11.64s , -18d 02m 59.8s) |   C |    60 | 18.2 |        
   26452 | 2021-08-27 17:30:37 |   MASTER-Kislovodsk | (20h 25m 25.65s , -19d 31m 23.4s) |   C |    60 | 17.5 |        
   26452 | 2021-08-27 17:30:37 |   MASTER-Kislovodsk | (20h 30m 01.38s , -19d 56m 58.4s) |   C |    60 | 18.1 |        
   27014 | 2021-08-27 17:39:59 |   MASTER-Kislovodsk | (20h 31m 11.23s , -15d 44m 54.0s) |   C |    60 | 17.5 |        
   27014 | 2021-08-27 17:39:59 |   MASTER-Kislovodsk | (20h 35m 43.24s , -16d 10m 21.8s) |   C |    60 | 18.2 |        
   27174 | 2021-08-27 17:42:40 |   MASTER-Kislovodsk | (20h 24m 24.36s , -21d 25m 55.7s) |   C |    60 | 17.5 |        
   27174 | 2021-08-27 17:42:40 |   MASTER-Kislovodsk | (20h 29m 03.61s , -21d 51m 33.9s) |   C |    60 | 18.1 |        
   27575 | 2021-08-27 17:49:20 |   MASTER-Kislovodsk | (20h 41m 31.97s , -19d 31m 13.5s) |   C |    60 | 17.5 |        
   27575 | 2021-08-27 17:49:20 |   MASTER-Kislovodsk | (20h 46m 07.89s , -19d 56m 48.7s) |   C |    60 | 18.2 |        
   27816 | 2021-08-27 17:53:21 |   MASTER-Kislovodsk | (20h 43m 33.76s , -17d 38m 08.2s) |   C |    60 | 17.5 |        
   27816 | 2021-08-27 17:53:21 |   MASTER-Kislovodsk | (20h 48m 07.55s , -18d 03m 38.8s) |   C |    60 | 18.1 |        
   27976 | 2021-08-27 17:56:02 |   MASTER-Kislovodsk | (20h 31m 16.12s , -15d 44m 00.6s) |   C |    60 | 17.6 |        
   27976 | 2021-08-27 17:56:02 |   MASTER-Kislovodsk | (20h 35m 48.31s , -16d 09m 26.7s) |   C |    60 | 18.2 |        
   28137 | 2021-08-27 17:58:42 |   MASTER-Kislovodsk | (20h 24m 31.19s , -21d 26m 25.0s) |   C |    60 | 17.5 |        
   28137 | 2021-08-27 17:58:43 |   MASTER-Kislovodsk | (20h 29m 10.79s , -21d 52m 01.6s) |   C |    60 | 18.2 |        
   28537 | 2021-08-27 18:05:23 |   MASTER-Kislovodsk | (20h 46m 07.24s , -19d 56m 31.8s) |   C |    60 | 18.0 |        
   28537 | 2021-08-27 18:05:23 |   MASTER-Kislovodsk | (20h 41m 30.66s , -19d 30m 59.4s) |   C |    60 | 17.4 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB210827A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30736
SUBJECT: Fermi GRB 210827A: Global MASTER-Net observations report 
DATE:    21/08/28 14:15:15 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev, O.Ershova 
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

V. Yurkov, A. Gabovich, Yu. Sergienko 
(Blagoveschensk Educational State University)




MASTER-Kislovodsk robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 210827A ( Fermi GBM team, GCN 30724) errorbox  30492 sec after notice time and 30537 sec after trigger time at 2021-08-27 18:28:21 UT, with upper limit up to  18.1 mag. The observations began at zenith distance = 70 deg. The sun  altitude  is -25.3 deg. 

The galactic latitude b = 41 deg., longitude l = 155 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1701371

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

   11650 | 2021-08-27 13:13:33 |             MASTER- | (11h 12m 36.70s , +67d 11m 16.1s) |   C |     1 | 13.4 |        
   11918 | 2021-08-27 13:17:59 |             MASTER- | (11h 46m 32.91s , +55d 47m 35.7s) |   C |     5 | 13.7 |        
   11947 | 2021-08-27 13:18:27 |             MASTER- | (11h 55m 02.70s , +57d 44m 41.4s) |   C |     5 | 14.1 |        
   12173 | 2021-08-27 13:22:14 |             MASTER- | (10h 01m 20.63s , +69d 03m 02.1s) |   C |     5 | 15.1 |        
   12194 | 2021-08-27 13:22:35 |             MASTER- | (09h 45m 27.80s , +65d 14m 47.8s) |   C |     5 | 14.9 |        
   12211 | 2021-08-27 13:22:52 |             MASTER- | (09h 52m 33.30s , +67d 08m 02.1s) |   C |     5 | 14.8 |        
   12228 | 2021-08-27 13:23:09 |             MASTER- | (11h 00m 38.41s , +70d 57m 53.9s) |   C |     5 | 15.5 |        
   12254 | 2021-08-27 13:23:32 |             MASTER- | (10h 22m 38.11s , +65d 14m 38.6s) |   C |    10 | 15.2 |        
   12274 | 2021-08-27 13:23:53 |             MASTER- | (10h 32m 28.63s , +67d 09m 16.9s) |   C |    10 | 14.9 |        
   12306 | 2021-08-27 13:24:25 |             MASTER- | (10h 44m 58.15s , +69d 03m 57.8s) |   C |    10 | 15.4 |        
   12332 | 2021-08-27 13:24:51 |             MASTER- | (11h 20m 42.93s , +72d 54m 50.1s) |   C |    10 | 15.5 |        
   12357 | 2021-08-27 13:25:16 |             MASTER- | (10h 14m 37.53s , +63d 20m 51.7s) |   C |    10 | 15.0 |        
   12383 | 2021-08-27 13:25:42 |             MASTER- | (09h 32m 58.63s , +59d 31m 17.2s) |   C |    10 | 14.7 |        
   12415 | 2021-08-27 13:26:14 |             MASTER- | (10h 03m 32.71s , +59d 31m 40.8s) |   C |    10 | 14.7 |        
   12441 | 2021-08-27 13:26:40 |             MASTER- | (09h 30m 48.25s , +57d 33m 40.2s) |   C |    10 | 14.2 |        
   12467 | 2021-08-27 13:27:05 |             MASTER- | (11h 28m 35.54s , +69d 03m 40.2s) |   C |    10 | 15.7 |        
   12487 | 2021-08-27 13:27:26 |             MASTER- | (11h 46m 30.04s , +74d 48m 24.7s) |   C |    10 | 15.5 |        
   12515 | 2021-08-27 13:27:53 |             MASTER- | (09h 04m 11.03s , +51d 49m 54.5s) |   C |    10 | 13.6 |        
   12550 | 2021-08-27 13:28:28 |             MASTER- | (09h 29m 10.43s , +53d 47m 35.1s) |   C |    10 | 14.7 |        
   12576 | 2021-08-27 13:28:55 |             MASTER- | (09h 59m 46.06s , +57d 36m 24.2s) |   C |    10 | 14.2 |        
   12596 | 2021-08-27 13:29:15 |             MASTER- | (09h 36m 05.99s , +61d 24m 19.6s) |   C |    10 | 15.0 |        
   12622 | 2021-08-27 13:29:41 |             MASTER- | (09h 29m 46.69s , +55d 40m 55.7s) |   C |    10 | 14.7 |        
   12655 | 2021-08-27 13:30:13 |             MASTER- | (10h 08m 27.79s , +61d 23m 46.2s) |   C |    10 | 15.1 |        
   12686 | 2021-08-27 13:30:45 |             MASTER- | (10h 59m 45.12s , +65d 13m 05.6s) |   C |    10 | 15.3 |        
   12710 | 2021-08-27 13:31:08 |             MASTER- | (09h 40m 15.47s , +63d 17m 48.7s) |   C |    10 | 13.3 |        
   12738 | 2021-08-27 13:31:34 |             MASTER- | (11h 12m 47.15s , +67d 08m 17.3s) |   C |    15 | 15.4 |        
   12738 | 2021-08-27 13:31:34 |             MASTER- | (11h 33m 48.90s , +68d 29m 16.4s) |   C |    15 | 14.1 |        
   12780 | 2021-08-27 13:32:16 |             MASTER- | (09h 06m 01.09s , +49d 57m 40.5s) |   C |    15 | 14.4 |        
   12780 | 2021-08-27 13:32:16 |             MASTER- | (09h 18m 00.30s , +51d 19m 06.1s) |   C |    15 | 12.7 |        
   12806 | 2021-08-27 13:32:42 |             MASTER- | (09h 56m 59.13s , +55d 40m 23.3s) |   C |    15 | 14.7 |        
   12806 | 2021-08-27 13:32:42 |             MASTER- | (10h 10m 59.95s , +57d 01m 11.1s) |   C |    15 | 13.2 |        
   12836 | 2021-08-27 13:33:12 |             MASTER- | (11h 48m 50.32s , +70d 59m 28.3s) |   C |    15 | 15.7 |        
   12910 | 2021-08-27 13:34:26 |             MASTER- | (10h 40m 39.02s , +61d 26m 55.2s) |   C |    15 | 15.3 |        
   12910 | 2021-08-27 13:34:26 |             MASTER- | (10h 57m 34.22s , +62d 46m 02.2s) |   C |    15 | 13.3 |        
   12940 | 2021-08-27 13:34:54 |             MASTER- | (09h 29m 11.96s , +51d 52m 23.5s) |   C |    20 | 14.8 |        
   12940 | 2021-08-27 13:34:54 |             MASTER- | (09h 41m 50.47s , +53d 10m 58.8s) |   C |    20 | 12.8 |        
   13025 | 2021-08-27 13:36:19 |             MASTER- | (10h 49m 17.27s , +63d 20m 37.8s) |   C |    20 | 15.5 |        
   13025 | 2021-08-27 13:36:19 |             MASTER- | (11h 07m 11.77s , +64d 40m 09.6s) |   C |    20 | 13.5 |        
   13062 | 2021-08-27 13:36:52 |             MASTER- | (12h 13m 57.24s , +72d 56m 00.0s) |   C |    25 | 14.4 |        
   13200 | 2021-08-27 13:39:09 |             MASTER- | (11h 46m 38.50s , +55d 46m 53.8s) |   C |    30 | 15.4 |        
   13200 | 2021-08-27 13:39:09 |             MASTER- | (12h 00m 55.06s , +57d 06m 14.3s) |   C |    30 | 13.9 |        
   13242 | 2021-08-27 13:39:48 |             MASTER- | (11h 55m 06.51s , +57d 41m 00.0s) |   C |    35 | 16.4 |        
   13914 | 2021-08-27 13:50:53 |             MASTER- | (10h 05m 07.14s , +66d 32m 23.8s) |   C |    50 | 14.4 |        
   13988 | 2021-08-27 13:52:03 |             MASTER- | (10h 13m 32.56s , +68d 26m 04.6s) |   C |    55 | 14.0 |        
   14071 | 2021-08-27 13:53:26 |             MASTER- | (11h 26m 13.82s , +72d 18m 56.3s) |   C |    55 | 14.7 |        
   14142 | 2021-08-27 13:54:36 |             MASTER- | (10h 22m 46.72s , +65d 13m 18.1s) |   C |    60 | 14.4 |        
   14223 | 2021-08-27 13:55:57 |             MASTER- | (10h 32m 39.17s , +67d 06m 40.3s) |   C |    60 | 15.1 |        
   14305 | 2021-08-27 13:57:18 |             MASTER- | (10h 45m 10.68s , +69d 01m 17.8s) |   C |    60 | 14.9 |        
   14305 | 2021-08-27 13:57:18 |             MASTER- | (11h 08m 24.23s , +70d 21m 59.0s) |   C |    60 | 14.6 |        
   14461 | 2021-08-27 13:59:55 |             MASTER- | (10h 32m 48.00s , +64d 38m 12.2s) |   C |    60 | 14.3 |        
   14547 | 2021-08-27 14:01:20 |             MASTER- | (09h 48m 55.04s , +60d 49m 31.6s) |   C |    60 | 13.8 |        
   14617 | 2021-08-27 14:02:31 |             MASTER- | (10h 03m 35.61s , +59d 29m 02.7s) |   C |    60 | 13.0 |        
   15032 | 2021-08-27 14:09:26 |             MASTER- | (09h 42m 24.32s , +55d 06m 08.6s) |   C |    60 | 14.5 |        
   15103 | 2021-08-27 14:10:37 |             MASTER- | (10h 00m 00.22s , +57d 32m 08.8s) |   C |    60 | 14.1 |        
   15267 | 2021-08-27 14:13:21 |             MASTER- | (09h 43m 39.34s , +57d 00m 17.0s) |   C |    60 | 14.6 |        
   15267 | 2021-08-27 14:13:21 |             MASTER- | (09h 29m 51.06s , +55d 38m 39.9s) |   C |    60 | 16.0 |        
   15337 | 2021-08-27 14:14:32 |             MASTER- | (10h 08m 42.40s , +61d 22m 46.0s) |   C |    55 | 13.7 |        
   15412 | 2021-08-27 14:15:51 |             MASTER- | (11h 19m 12.19s , +66d 33m 52.9s) |   C |    50 | 15.0 |        
   15475 | 2021-08-27 14:16:54 |             MASTER- | (09h 58m 16.72s , +64d 35m 36.7s) |   C |    50 | 14.1 |        
   15475 | 2021-08-27 14:16:54 |             MASTER- | (09h 40m 29.81s , +63d 14m 20.6s) |   C |    50 | 15.9 |        
   15556 | 2021-08-27 14:18:12 |             MASTER- | (11h 13m 03.21s , +67d 05m 51.4s) |   C |    55 | 12.4 |        
   15638 | 2021-08-27 14:19:34 |             MASTER- | (10h 11m 12.98s , +57d 00m 30.2s) |   C |    55 | 14.4 |        
   15638 | 2021-08-27 14:19:34 |             MASTER- | (09h 57m 16.48s , +55d 38m 20.8s) |   C |    55 | 14.8 |        
   15708 | 2021-08-27 14:20:44 |             MASTER- | (12h 14m 11.05s , +72d 18m 07.1s) |   C |    55 | 15.0 |        
   15708 | 2021-08-27 14:20:44 |             MASTER- | (11h 49m 02.98s , +70d 57m 13.0s) |   C |    55 | 14.9 |        
   15949 | 2021-08-27 14:24:42 |             MASTER- | (09h 41m 57.90s , +53d 11m 40.0s) |   C |    60 | 13.6 |        
   16123 | 2021-08-27 14:27:42 |             MASTER- | (10h 49m 44.99s , +63d 17m 26.4s) |   C |    50 | 14.2 |        
   16192 | 2021-08-27 14:28:45 |             MASTER- | (12h 14m 20.14s , +72d 52m 25.9s) |   C |    60 | 13.6 |        
   16595 | 2021-08-27 14:35:39 |             MASTER- | (11h 46m 34.30s , +55d 44m 13.6s) |   C |    40 | 15.1 |        
   16644 | 2021-08-27 14:36:28 |             MASTER- | (12h 10m 25.31s , +58d 58m 20.1s) |   C |    40 | 13.5 |        
   16755 | 2021-08-27 14:38:29 |             MASTER- | (11h 41m 24.68s , +58d 58m 33.2s) |   C |    20 | 13.7 |        
   16755 | 2021-08-27 14:38:29 |             MASTER- | (11h 26m 19.64s , +57d 38m 07.6s) |   C |    20 | 14.7 |        
   16787 | 2021-08-27 14:39:01 |             MASTER- | (12h 05m 35.42s , +59d 34m 15.7s) |   C |    20 | 15.6 |        
   16852 | 2021-08-27 14:40:06 |             MASTER- | (11h 04m 34.20s , +59d 33m 06.4s) |   C |    20 | 16.1 |        
   16959 | 2021-08-27 14:41:53 |             MASTER- | (11h 53m 15.95s , +55d 10m 45.9s) |   C |    20 | 13.8 |        
   16959 | 2021-08-27 14:41:53 |             MASTER- | (11h 39m 38.11s , +53d 49m 19.8s) |   C |    20 | 15.7 |        
   17022 | 2021-08-27 14:42:56 |             MASTER- | (11h 33m 29.78s , +57d 03m 39.7s) |   C |    20 | 13.4 |        
   17022 | 2021-08-27 14:42:56 |             MASTER- | (11h 19m 19.52s , +55d 42m 47.1s) |   C |    20 | 15.0 |        
   17331 | 2021-08-27 14:48:05 |             MASTER- | (12h 05m 29.24s , +59d 32m 27.7s) |   C |    20 | 15.6 |        
   17407 | 2021-08-27 14:49:21 |             MASTER- | (11h 20m 40.57s , +60d 51m 48.6s) |   C |    20 | 13.2 |        
   17407 | 2021-08-27 14:49:21 |             MASTER- | (11h 04m 44.06s , +59d 32m 05.8s) |   C |    20 | 15.8 |        
   17437 | 2021-08-27 14:49:51 |             MASTER- | (11h 51m 08.81s , +60d 51m 10.7s) |   C |    20 | 13.7 |        
   17498 | 2021-08-27 14:50:52 |             MASTER- | (11h 53m 13.08s , +55d 11m 34.7s) |   C |    20 | 13.6 |        
   17498 | 2021-08-27 14:50:52 |             MASTER- | (11h 39m 43.02s , +53d 50m 41.5s) |   C |    20 | 16.1 |        
   17671 | 2021-08-27 14:53:45 |             MASTER- | (11h 33m 36.97s , +57d 02m 27.0s) |   C |    20 | 13.4 |        
   17671 | 2021-08-27 14:53:45 |             MASTER- | (11h 19m 27.44s , +55d 42m 15.9s) |   C |    20 | 15.8 |        
   17700 | 2021-08-27 14:54:13 |             MASTER- | (11h 41m 33.01s , +58d 56m 46.1s) |   C |    20 | 13.0 |        
   17700 | 2021-08-27 14:54:13 |             MASTER- | (11h 26m 33.07s , +57d 35m 35.3s) |   C |    20 | 15.5 |        
   17731 | 2021-08-27 14:54:44 |             MASTER- | (12h 05m 41.38s , +59d 32m 22.8s) |   C |    20 | 15.7 |        
   17838 | 2021-08-27 14:56:31 |             MASTER- | (11h 51m 09.60s , +60d 51m 57.3s) |   C |    20 | 13.4 |        
   17909 | 2021-08-27 14:57:43 |             MASTER- | (11h 53m 25.45s , +55d 09m 54.2s) |   C |    20 | 13.4 |        
   17910 | 2021-08-27 14:57:43 |             MASTER- | (11h 39m 53.42s , +53d 49m 25.3s) |   C |    20 | 14.4 |        
   18101 | 2021-08-27 15:00:55 |             MASTER- | (11h 30m 26.09s , +62d 46m 41.0s) |   C |    20 | 13.3 |        
   18101 | 2021-08-27 15:00:55 |             MASTER- | (11h 13m 32.12s , +61d 24m 19.9s) |   C |    20 | 15.3 |        
   18289 | 2021-08-27 15:04:03 |             MASTER- | (10h 50m 08.24s , +60d 49m 28.9s) |   C |    20 | 13.2 |        
   18289 | 2021-08-27 15:04:03 |             MASTER- | (10h 34m 30.40s , +59d 27m 37.8s) |   C |    20 | 15.0 |        
   18320 | 2021-08-27 15:04:34 |             MASTER- | (11h 12m 38.32s , +58d 55m 08.8s) |   C |    20 | 13.1 |        
   18320 | 2021-08-27 15:04:34 |             MASTER- | (10h 57m 47.86s , +57d 33m 14.5s) |   C |    20 | 15.4 |        
   18362 | 2021-08-27 15:05:15 |             MASTER- | (11h 06m 20.08s , +57d 01m 27.5s) |   C |    20 | 13.0 |        
   18362 | 2021-08-27 15:05:15 |             MASTER- | (10h 52m 19.20s , +55d 40m 37.6s) |   C |    20 | 15.6 |        
   18392 | 2021-08-27 15:05:46 |             MASTER- | (10h 28m 58.66s , +57d 34m 29.6s) |   C |    20 | 15.1 |        
   18425 | 2021-08-27 15:06:18 |             MASTER- | (11h 30m 27.14s , +62d 43m 49.0s) |   C |    20 | 13.7 |        
   18425 | 2021-08-27 15:06:19 |             MASTER- | (11h 13m 38.18s , +61d 21m 52.5s) |   C |    20 | 15.4 |        
   18457 | 2021-08-27 15:06:51 |             MASTER- | (11h 27m 12.37s , +55d 10m 55.6s) |   C |    20 | 14.0 |        
   18457 | 2021-08-27 15:06:51 |             MASTER- | (11h 13m 56.70s , +53d 48m 49.0s) |   C |    20 | 15.9 |        
   18501 | 2021-08-27 15:07:35 |             MASTER- | (10h 24m 46.08s , +55d 38m 36.4s) |   C |    20 | 14.5 |        
   18534 | 2021-08-27 15:08:07 |             MASTER- | (11h 42m 11.95s , +64d 40m 53.6s) |   C |    20 | 13.5 |        
   18534 | 2021-08-27 15:08:07 |             MASTER- | (11h 24m 23.30s , +63d 18m 59.1s) |   C |    20 | 16.2 |        
   18565 | 2021-08-27 15:08:39 |             MASTER- | (10h 34m 31.63s , +59d 27m 03.1s) |   C |    20 | 15.1 |        
   18609 | 2021-08-27 15:09:23 |             MASTER- | (12h 02m 46.48s , +62d 45m 03.1s) |   C |    20 | 13.9 |        
   18609 | 2021-08-27 15:09:23 |             MASTER- | (11h 45m 56.18s , +61d 22m 25.8s) |   C |    20 | 15.6 |        
   18641 | 2021-08-27 15:09:55 |             MASTER- | (11h 12m 40.13s , +58d 56m 25.2s) |   C |    20 | 12.6 |        
   18641 | 2021-08-27 15:09:55 |             MASTER- | (10h 57m 54.03s , +57d 33m 53.4s) |   C |    20 | 14.1 |        
   18670 | 2021-08-27 15:10:23 |             MASTER- | (11h 06m 17.28s , +57d 02m 08.4s) |   C |    20 | 13.2 |        
   18670 | 2021-08-27 15:10:23 |             MASTER- | (10h 52m 11.20s , +55d 40m 04.5s) |   C |    20 | 15.7 |        
   18699 | 2021-08-27 15:10:53 |             MASTER- | (10h 29m 08.31s , +57d 31m 46.3s) |   C |    20 | 15.6 |        
   18741 | 2021-08-27 15:11:35 |             MASTER- | (11h 30m 22.56s , +62d 46m 13.4s) |   C |    20 | 13.2 |        
   18741 | 2021-08-27 15:11:35 |             MASTER- | (11h 13m 42.26s , +61d 23m 06.9s) |   C |    20 | 15.1 |        
   18773 | 2021-08-27 15:12:07 |             MASTER- | (11h 27m 03.50s , +55d 08m 24.0s) |   C |    20 | 13.5 |        
   18773 | 2021-08-27 15:12:07 |             MASTER- | (11h 13m 46.34s , +53d 46m 13.3s) |   C |    20 | 15.3 |        
   18806 | 2021-08-27 15:12:40 |             MASTER- | (10h 24m 53.25s , +55d 40m 46.0s) |   C |    20 | 15.4 |        
   18850 | 2021-08-27 15:13:24 |             MASTER- | (11h 24m 28.50s , +63d 18m 00.7s) |   C |    20 | 15.5 |        
   18882 | 2021-08-27 15:13:56 |             MASTER- | (10h 49m 58.75s , +60d 47m 44.8s) |   C |    20 | 13.1 |        
   18882 | 2021-08-27 15:13:56 |             MASTER- | (10h 34m 27.05s , +59d 25m 47.8s) |   C |    20 | 15.1 |        
   18916 | 2021-08-27 15:14:30 |             MASTER- | (12h 02m 45.53s , +62d 45m 44.1s) |   C |    20 | 14.1 |        
   18916 | 2021-08-27 15:14:30 |             MASTER- | (11h 46m 11.43s , +61d 23m 24.9s) |   C |    20 | 15.8 |        
   19029 | 2021-08-27 15:16:23 |             MASTER- | (10h 29m 12.51s , +57d 33m 18.2s) |   C |    20 | 14.8 |        
   19114 | 2021-08-27 15:17:48 |             MASTER- | (11h 13m 46.37s , +53d 48m 10.8s) |   C |    20 | 14.8 |        
   19148 | 2021-08-27 15:18:22 |             MASTER- | (10h 24m 59.00s , +55d 39m 36.6s) |   C |    20 | 15.3 |        
   19148 | 2021-08-27 15:18:22 |             MASTER- | (10h 38m 47.02s , +57d 01m 12.7s) |   C |    20 | 13.3 |        
   19181 | 2021-08-27 15:18:54 |             MASTER- | (11h 24m 25.91s , +63d 15m 26.2s) |   C |    20 | 16.0 |        
   19181 | 2021-08-27 15:18:54 |             MASTER- | (11h 42m 09.52s , +64d 37m 52.2s) |   C |    20 | 13.5 |        
   19263 | 2021-08-27 15:20:17 |             MASTER- | (12h 02m 45.57s , +62d 45m 12.2s) |   C |    20 | 13.3 |        
   19263 | 2021-08-27 15:20:17 |             MASTER- | (11h 46m 03.30s , +61d 24m 27.2s) |   C |    20 | 14.6 |        
   20984 | 2021-08-27 15:48:58 |             MASTER- | (11h 58m 41.13s , +63d 18m 47.7s) |   C |    20 | 15.2 |        
   20984 | 2021-08-27 15:48:58 |             MASTER- | (12h 16m 23.96s , +64d 38m 13.6s) |   C |    20 | 13.7 |        
   21198 | 2021-08-27 15:52:31 |             MASTER- | (12h 18m 28.25s , +61d 25m 56.1s) |   C |    20 | 16.0 |        
   21243 | 2021-08-27 15:53:17 |             MASTER- | (11h 37m 13.80s , +65d 11m 07.4s) |   C |    20 | 15.6 |        
   21243 | 2021-08-27 15:53:17 |             MASTER- | (11h 56m 11.10s , +66d 31m 57.7s) |   C |    20 | 14.3 |        
   21413 | 2021-08-27 15:56:06 |             MASTER- | (11h 58m 50.70s , +63d 16m 39.0s) |   C |    20 | 15.5 |        
   21413 | 2021-08-27 15:56:06 |             MASTER- | (12h 16m 49.59s , +64d 37m 34.9s) |   C |    20 | 13.7 |        
   21628 | 2021-08-27 15:59:42 |             MASTER- | (12h 18m 20.92s , +61d 24m 54.9s) |   C |    20 | 15.4 |        
   21659 | 2021-08-27 16:00:13 |             MASTER- | (11h 37m 37.23s , +65d 12m 07.7s) |   C |    20 | 16.2 |        
   21659 | 2021-08-27 16:00:13 |             MASTER- | (11h 56m 49.55s , +66d 33m 14.8s) |   C |    20 | 13.8 |        
   21747 | 2021-08-27 16:01:41 |             MASTER- | (11h 58m 58.79s , +63d 16m 33.4s) |   C |    20 | 15.5 |        
   21810 | 2021-08-27 16:02:44 |             MASTER- | (12h 14m 37.59s , +65d 11m 02.4s) |   C |    20 | 15.1 |        
   21916 | 2021-08-27 16:04:30 |             MASTER- | (11h 53m 19.32s , +67d 06m 12.1s) |   C |    20 | 15.4 |        
   21916 | 2021-08-27 16:04:30 |             MASTER- | (12h 14m 25.09s , +68d 26m 50.1s) |   C |    20 | 13.5 |        
   21991 | 2021-08-27 16:05:45 |             MASTER- | (11h 37m 35.11s , +65d 10m 53.9s) |   C |    20 | 16.2 |        
   22134 | 2021-08-27 16:08:08 |             MASTER- | (12h 14m 42.20s , +65d 12m 17.2s) |   C |    20 | 15.3 |        
   22240 | 2021-08-27 16:09:54 |             MASTER- | (11h 53m 38.72s , +67d 04m 55.2s) |   C |    20 | 15.5 |        
   22455 | 2021-08-27 16:13:29 |             MASTER- | (12h 14m 38.21s , +65d 11m 15.0s) |   C |    20 | 15.1 |        
   22564 | 2021-08-27 16:15:17 |             MASTER- | (11h 53m 25.23s , +67d 03m 34.6s) |   C |    20 | 15.3 |        
   22564 | 2021-08-27 16:15:17 |             MASTER- | (12h 14m 26.56s , +68d 25m 29.5s) |   C |    20 | 13.1 |        
   30567 | 2021-08-27 18:28:21 |   MASTER-Kislovodsk | (06h 19m 12.16s , +65d 20m 16.3s) |   C |    60 | 17.8 |        
   30567 | 2021-08-27 18:28:21 |   MASTER-Kislovodsk | (06h 09m 28.58s , +65d 45m 46.2s) |   C |    60 | 17.2 |        
   30647 | 2021-08-27 18:29:41 |   MASTER-Kislovodsk | (05h 59m 00.90s , +69d 08m 32.6s) |   C |    60 | 17.9 |        
   30728 | 2021-08-27 18:31:01 |   MASTER-Kislovodsk | (06h 09m 43.61s , +67d 15m 56.9s) |   C |    60 | 17.8 |        
   30728 | 2021-08-27 18:31:02 |   MASTER-Kislovodsk | (05h 59m 11.65s , +67d 41m 30.7s) |   C |    60 | 17.3 |        
   30808 | 2021-08-27 18:32:21 |   MASTER-Kislovodsk | (06h 42m 26.91s , +69d 08m 09.5s) |   C |    60 | 18.0 |        
   30808 | 2021-08-27 18:32:21 |   MASTER-Kislovodsk | (06h 30m 58.61s , +69d 33m 45.3s) |   C |    60 | 17.5 |        
   30968 | 2021-08-27 18:35:02 |   MASTER-Kislovodsk | (06h 34m 19.20s , +71d 02m 14.1s) |   C |    60 | 18.1 |        
   30968 | 2021-08-27 18:35:02 |   MASTER-Kislovodsk | (06h 20m 50.93s , +71d 28m 30.0s) |   C |    60 | 17.5 |        
   31048 | 2021-08-27 18:36:22 |   MASTER-Kislovodsk | (06h 49m 41.09s , +67d 15m 25.5s) |   C |    60 | 17.9 |        
   31048 | 2021-08-27 18:36:22 |   MASTER-Kislovodsk | (06h 38m 26.91s , +67d 41m 30.2s) |   C |    60 | 17.3 |        
   31289 | 2021-08-27 18:40:23 |   MASTER-Kislovodsk | (07h 02m 22.14s , +63d 26m 32.4s) |   C |    60 | 17.7 |        
   31289 | 2021-08-27 18:40:23 |   MASTER-Kislovodsk | (06h 53m 18.49s , +63d 52m 02.4s) |   C |    60 | 17.2 |        
   31530 | 2021-08-27 18:44:23 |   MASTER-Kislovodsk | (06h 19m 19.21s , +65d 22m 04.8s) |   C |    60 | 17.7 |        
   31530 | 2021-08-27 18:44:23 |   MASTER-Kislovodsk | (06h 09m 33.40s , +65d 47m 39.7s) |   C |    60 | 17.3 |        
   31610 | 2021-08-27 18:45:44 |   MASTER-Kislovodsk | (05h 58m 59.89s , +69d 10m 29.9s) |   C |    60 | 17.8 |        
   31690 | 2021-08-27 18:47:04 |   MASTER-Kislovodsk | (06h 09m 43.67s , +67d 16m 29.4s) |   C |    60 | 17.8 |        
   31690 | 2021-08-27 18:47:04 |   MASTER-Kislovodsk | (05h 59m 09.68s , +67d 42m 07.1s) |   C |    60 | 17.3 |        
   31770 | 2021-08-27 18:48:24 |   MASTER-Kislovodsk | (06h 42m 33.83s , +69d 10m 02.7s) |   C |    60 | 17.8 |        
   31770 | 2021-08-27 18:48:24 |   MASTER-Kislovodsk | (06h 31m 02.76s , +69d 35m 44.1s) |   C |    60 | 17.4 |        
   31930 | 2021-08-27 18:51:04 |   MASTER-Kislovodsk | (06h 34m 27.39s , +71d 01m 52.5s) |   C |    60 | 17.9 |        
   31930 | 2021-08-27 18:51:04 |   MASTER-Kislovodsk | (06h 20m 59.22s , +71d 28m 15.0s) |   C |    60 | 17.5 |        
   32010 | 2021-08-27 18:52:24 |   MASTER-Kislovodsk | (06h 49m 46.79s , +67d 15m 06.0s) |   C |    60 | 17.8 |        
   32010 | 2021-08-27 18:52:24 |   MASTER-Kislovodsk | (06h 38m 32.52s , +67d 41m 16.8s) |   C |    60 | 17.3 |        
   32250 | 2021-08-27 18:56:24 |   MASTER-Kislovodsk | (07h 02m 18.77s , +63d 27m 17.3s) |   C |    60 | 17.5 |        
   32250 | 2021-08-27 18:56:24 |   MASTER-Kislovodsk | (06h 53m 14.25s , +63d 52m 52.2s) |   C |    60 | 17.2 |        
   32330 | 2021-08-27 18:57:44 |   MASTER-Kislovodsk | (07h 03m 30.23s , +63d 27m 18.2s) |   C |    60 | 12.9 |        
   32330 | 2021-08-27 18:57:44 |   MASTER-Kislovodsk | (06h 53m 55.14s , +63d 52m 53.5s) |   C |    60 | 12.6 |        
   32455 | 2021-08-27 19:00:09 |             MASTER- | (12h 14m 44.53s , +68d 57m 28.0s) |   C |    20 | 13.7 |        
   32490 | 2021-08-27 19:00:24 |   MASTER-Kislovodsk | (06h 19m 27.91s , +65d 20m 04.7s) |   C |    60 | 17.6 |        
   32491 | 2021-08-27 19:00:24 |   MASTER-Kislovodsk | (06h 09m 05.21s , +65d 46m 08.9s) |   C |    60 | 17.2 |        
   32571 | 2021-08-27 19:01:45 |   MASTER-Kislovodsk | (05h 59m 19.02s , +69d 08m 32.7s) |   C |    60 | 17.7 |        
   32570 | 2021-08-27 19:02:04 |             MASTER- | (12h 27m 03.52s , +66d 38m 29.9s) |   C |    20 | 12.9 |        
   32651 | 2021-08-27 19:03:05 |   MASTER-Kislovodsk | (06h 10m 01.33s , +67d 16m 04.2s) |   C |    60 | 17.6 |        
   32651 | 2021-08-27 19:03:05 |   MASTER-Kislovodsk | (05h 58m 46.72s , +67d 42m 11.9s) |   C |    60 | 17.3 |        
   32671 | 2021-08-27 19:03:45 |             MASTER- | (12h 28m 10.18s , +69d 57m 04.0s) |   C |    20 | 13.6 |        
   32731 | 2021-08-27 19:04:25 |   MASTER-Kislovodsk | (06h 42m 44.87s , +69d 07m 44.1s) |   C |    60 | 17.8 |        
   32731 | 2021-08-27 19:04:25 |   MASTER-Kislovodsk | (06h 30m 31.28s , +69d 33m 55.1s) |   C |    60 | 17.4 |        
   32892 | 2021-08-27 19:07:06 |   MASTER-Kislovodsk | (06h 34m 34.94s , +71d 02m 29.4s) |   C |    60 | 17.9 |        
   32892 | 2021-08-27 19:07:06 |   MASTER-Kislovodsk | (06h 21m 06.53s , +71d 28m 55.4s) |   C |    60 | 17.4 |        
   32905 | 2021-08-27 19:07:39 |             MASTER- | (06h 25m 59.85s , +64d 20m 01.2s) |   C |    20 | 13.1 |        
   32935 | 2021-08-27 19:08:09 |             MASTER- | (06h 54m 15.07s , +66d 15m 32.0s) |   C |    20 | 12.0 |        
   32972 | 2021-08-27 19:08:26 |   MASTER-Kislovodsk | (06h 49m 56.53s , +67d 15m 38.0s) |   C |    60 | 17.7 |        
   32972 | 2021-08-27 19:08:26 |   MASTER-Kislovodsk | (06h 38m 41.88s , +67d 41m 52.3s) |   C |    60 | 17.3 |        
   33212 | 2021-08-27 19:12:26 |   MASTER-Kislovodsk | (06h 52m 59.48s , +63d 52m 14.5s) |   C |    60 | 17.2 |        
   33213 | 2021-08-27 19:12:26 |   MASTER-Kislovodsk | (07h 02m 38.65s , +63d 26m 18.4s) |   C |    60 | 17.5 |        
   97622 | 2021-08-28 13:06:25 |             MASTER- | (11h 33m 38.59s , +55d 20m 48.5s) |   C |     1 | 12.5 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB210826A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30737
SUBJECT: GRB 210826A: AstroSat CZTI detection
DATE:    21/08/28 14:30:28 GMT
FROM:    Gaurav Waratkar at IIT,Bombay  <gauravwaratkar@iitb.ac.in>

V. Prasad (IUCAA), P. Sawant (IUCAA), G. Waratkar (IITB), A. Vibhute
(IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao
(IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat
CZTI collaboration:

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al,
2020, arxiv:2011.07067) showed detection of a long GRB 210826A, which
was also detected by Fermi-GBM (trigger no. 210826293, GCN 30716) and
Fermi-LAT (Ohno et al., GCN 30721).

The source was clearly detected in the 20-200 keV energy range. The
light curve showed multiple peaks of emission with the strongest peak at
2021-08-26 07:01:53.50 UT. The measured peak count rate associated with
the burst is 183 (+45, -24) cts/s above the background in the combined
data of four quadrants, with a total of 2161 (+327, -549) cts. The local
mean background count rate was 560 (+4, -2) cts/s. Using cumulative
rates, we measure a T90 of 24 (+17, -10) s.

It was also detected in the CsI anticoincidence (Veto) detector in the
100-500 keV energy range. The light curve showed multiple peaks of
emission with the strongest peak at 2021-08-26 07:01:47.03 UT. The
measured peak count rate is 200 (+95, -5) cts/s above the background in
the combined Veto data of four quadrants, with a total of 1953 (+648,
-720) cts. The local mean background count rate was 1907 (+6, -6) cts/s.
We measure a T90 of 14 (+8, -5) s from the cumulative Veto light curve.

CZTI GRB detections are reported regularly on the payload site at
http://astrosat.iucaa.in/czti/?q=grb [1]. CZTI is built by a TIFR-led
consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC
and PRL. The Indian Space Research Organisation funded, managed and
facilitated the project. 

Links:
------
[1] http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB210827A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30738
SUBJECT: GRB 210827A: Fermi GBM Observation
DATE:    21/08/28 23:58:01 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076@uah.edu>

S. Lesage (UAH), R. Dunwoody (UCD), J. Mangan (UCD) and C. Meegan (UAH)
report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 09:59:24 UT on 27 August 2021, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 210827A (trigger 651751169/210827416)
which was also detected by Swift/BAT-GUANO (James DeLaunay et al. 2021, GCN
30732).
The Fermi GBM Final Real-time Localization (GCN 30724) is consistent with
the Swift/BAT-GUANO position.

The angle from the Fermi LAT boresight is 42 degrees.

The GBM light curve consists of a single emission episode with a duration
(T90)
of about 9 s (10-1000 keV). The time-averaged spectrum
from T0-2.0 to T0+4.1 s is best fit by
a simple power law function with index -1.6 +/- 0.1.

The event fluence (10-1000 keV) in this time interval is
(7 +/- 1)E-07 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-2.5 s in the 10-1000 keV band is 1.7 +/- 0.2 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support
Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB210827A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30742
SUBJECT: GRB 210827A: BOOTES-5/JGT optical upper limit
DATE:    21/08/29 16:06:32 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

Y.-D. Hu, T.-R. Sun, E. Fernandez-Garcia, A. J. Castro-Tirado and M.D. Caballero-Garcia (IAA-CSIC), D. Hiriart and W. H. Lee (UNAM), C. J. Perez del Pulgar and I. Carrasco (UMA), I. H. Park (SKKU) on behalf of a larger collaboration, report:

We triggered the 60cm BOOTES-5/JGT robotic telescope at Observatorio Astronomico Nacional in San Pedro Martir (Mexico) for the Fermi trigger of GRB 210827A (Fermi GBM team, GCNC 30724) in order to monitor the Swift/BAT-GUANO error region (DeLaunay et al. GCNC 30732) on 28 Aug 05:25 UT (~ 0.81 day after trigger). In the co-added clear image (8 x 60 s), no optical afterglow is detected within the BAT error region or at the source 3 position later reported by the Swift-XRT (Evans et al., GCNC 30733; Gropp et al., GCNC 30734) down to 19.7 mag. This non-detection is consistent with the report by MASTER-Net (Lipunov et al., GCNC 30736).

We thank the staff at Observatorio Astronomico Nacional in San Pedro Martir for its excellent support.


GRB_name: GRB210827A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30743
SUBJECT: GRB 210827A: Swift/UVOT Upper Limits
DATE:    21/08/29 16:16:11 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and P. D'Avanzo (INAF-OAB) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the Swift/BAT-GUANO-detected burst GRB 210827A 
(DeLaunay et al., GCN Circ. 30732) 44720s after the Fermi-GBM trigger (Fermi GBM team, GCN Circ. 
30724). No new optical source consistent with the candidate XRT positions (Gropp et al., GCN Circ. 
30734) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system (Breeveld et al. 2011, AIP Conf. 
Proc. 1358, 373) for the initial exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white            44720        50434         1650         >21.6

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of 
E(B-V) = 0.0111 in the direction of the burst (Schlegel et al. 1998).


GRB_name: GRB210822A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30744
SUBJECT: GRB 210822A: CALET Gamma-Ray Burst Monitor detection
DATE:    21/08/30 07:06:23 GMT
FROM:    Valentin Pal'shin at AGU  <val@phys.aoyama.ac.jp>

K. Kobayashi (Waseda U),
A. Yoshida, T. Sakamoto, V. Pal'shin, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (RIKEN),
Y. Asaoka (ICRR), S. Torii, Y. Akaike (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC),
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The long GRB 210822A (Swift detection: Page et al., GCN Circ. 30677, Lien
et al., GCN Circ. 30689; GECAM detection: Wang et al., GCN Circ. 30678,
30696; Fermi-LAT detection: Ohno et al., GCN Circ. 30687; AstroSat CZTI
detection: Prasad et al., GCN Circ. 30693; Konus-Wind detection:
Frederiks et al., GCN Circ. 30694; GRBAlpha detection: Ohno et al.,
GCN Circ. 30697; https://gcn.gsfc.nasa.gov/other/210822A.gcn3)
triggered the CALET Gamma-ray Burst Monitor (CGBM) at 09:18:18.162 UTC
on 22 August 2021. The burst signal was seen by all CGBM detectors.
Because of a problem in one of the ground alert processing script,
the GCN notice was not distributed automatically for this event.

The burst light curve shows a multi-peaked structure which starts at
T-0.2 sec, peaks at T+0.1 sec and ends at T+11.0 sec.
The T90 and T50 durations measured by the SGM data are 10.1 +- 0.5 sec
and 5.8 +- 0.4 sec (40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1313658800/

The CALET data used in this analysis are provided by
the Waseda CALET Operation Center located at the Waseda University.


GRB_name: GRB210827A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30745
SUBJECT: GRB 210827A: further Swift-XRT observations
DATE:    21/08/30 13:34:23 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <pda.davanzo@gmail.com>

P. D'Avanzo, M. G. Bernardini, A. Melandri, T. Sbarrato (INAF-OAB), P. A. Evans (U. Leicester)
 report on behalf of the Swift team:


Swift-XRT has performed further follow-up observations of the Swift/BAT-GUANO-detected burst 
GRB 210827A (James DeLaunay et al. GCN Circ. 30732), collecting a total of 12.2 ks of Photon 
Counting (PC) mode data between T0+44.4 ks and T0+257.2 ks. The uncatalogued candidate 
X-ray source (Source 3) reported in Gropp et al. (GCN Circ. 30734) faded to a count-rate of 3e-3 ct s^-1, 
thus suggesting it as the likely X-ray afterglow of GRB 210827A. The light curve can be described with 
a single power-law with a decay index alpha = 1.0 (+0.5, -0.4). 

The results of the XRT-team automatic analysis are available at https://www.swift.ac.uk/xrt_products/00021461 <https://www.swift.ac.uk/xrt_products/00021461> 


This circular is an official product of the Swift-XRT team.


GRB_name: GRB210901A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30746
SUBJECT: GRB 210901A: Swift detection of a burst
DATE:    21/09/01 15:22:09 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

S. Laha (GSFC/UMBC/CRESST), E. Ambrosi (INAF-IASFPA),
V. D'Elia (SSDC & INAF-OAR), P. A. Evans (U Leicester),
C. Gronwall (PSU), J. A. Kennea (PSU),
N. J. Klingler (GSFC/UMBC/CRESSTII), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL), M. H. Siegel (PSU) and
A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 15:04:36 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210901A (trigger=1071488).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 295.292, -76.932 which is 
   RA(J2000) = 19h 41m 10s
   Dec(J2000) = -76d 55' 55"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex structure
with a duration of about 60 sec. As this is an image trigger a more 
complete description of the lightcurve will require the ground pass data. 
The peak count rate was ~500 counts/sec (15-350 keV), at ~0 sec after 
the trigger. 

The XRT began observing the field at 15:07:07.7 UT, 151.4 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source with an enhanced position: RA, Dec
295.2774, -76.9263 which is equivalent to:
   RA(J2000)  = 19h 41m 06.57s
   Dec(J2000) = -76d 55' 34.8"
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This
location is 23 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at https://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 1.02
x 10^21 cm^-2 (Willingale et al. 2013). 

The initial flux in the 2.5 s image was 1.86e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 157 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers 100% of
the XRT error circle. The typical 3-sigma upper limit has been about 19.6 mag. 
The 8'x8' region for the list of sources generated on-board covers 100% of the
XRT error circle. The list of sources is typically complete to about 18 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.200. 

Burst Advocate for this burst is S. Laha (sib.laha AT gmail.com). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)


GRB_name: GRB210901A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30747
SUBJECT: Swift GRB 210901A: Global MASTER-Net observations report 
DATE:    21/09/01 17:23:41 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev, O.Ershova 
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

V. Yurkov, A. Gabovich, Yu. Sergienko 
(Blagoveschensk Educational State University)




MASTER-SAAO robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 210901A ( S. Laha et al., GCN 30746) errorbox  6860 sec after notice time and 6950 sec after trigger time at 2021-09-01 17:00:26 UT, with upper limit up to  18.6 mag. Observations started at twilight.  The observations began at zenith distance = 49 deg. The sun  altitude  is -8.9 deg. 

The galactic latitude b = -30 deg., longitude l = 318 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1706835

We obtain a following upper limits.  

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

    7040 |         MASTER-SAAO |   C |   180 | 17.4 |        
    7220 |         MASTER-SAAO |   C |   540 | 17.8 |  Coadd 
    7240 |         MASTER-SAAO |   C |   180 | 17.9 |        
    7439 |         MASTER-SAAO |   C |   180 | 18.3 |        
    7639 |         MASTER-SAAO |   C |   180 | 18.6 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB210901A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30748
SUBJECT: GRB 210901A: LCO Optical Upper Limit
DATE:    21/09/01 20:02:31 GMT
FROM:    Robert Strausbaugh at U. of the Virgin Islands  <robert.strausbaugh@uvi.edu>

R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration:

We observed Swift GRB 210901A (Laha, et al., GCN 30746) with the LCO 1-m Sinistro instrument at the South African Astronomical Observatory site, on September 1, from 17:14 to 17:36 UT (corresponding to 2.17 to 2.53 hours from the GRB trigger time) with the Bessel R and I filters.

We performed a series of 3x300s exposures in R and I. In the XRT detection region (Laha, et al., GCN 30746) no optical counterpart could be detected down to the following upper limits, calculated using the USNO-B.1 catalog as reference:

R>21.55

I>21.16

These magnitudes are not corrected for galactic extinction.

R.S. is funded by NSF AST grant #1831682


GRB_name: GRB210901A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30749
SUBJECT: GRB 210901A: Enhanced Swift-XRT position
DATE:    21/09/01 20:08:20 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 302 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 210901A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 295.27805, -76.92664 which is equivalent
to:

RA (J2000): 19h 41m 6.73s
Dec (J2000): -76d 55' 35.9"

with an uncertainty of 2.5 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB210901A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30750
SUBJECT: GRB 210901A: Swift-BAT refined analysis
DATE:    21/09/02 01:42:38 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

D. M. Palmer (LANL), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
T. Sakamoto (AGU), M. Stamatikos (OSU)
(i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 210901A (trigger #1071488)
(Laha et al., GCN Circ. 30746).  The BAT ground-calculated position is
RA, Dec = 295.224, -76.942 deg which is
   RA(J2000)  =  19h 40m 53.8s
   Dec(J2000) = -76d 56' 31.9"
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 12%.

The mask-weighted light curve shows a multi-peaked structure. The main
pulse structure start at ~T+30 s and ends at ~T+85 s, with the highest
peak occurring at ~T+60 s. In addition, there might be some weak emission
prior to the main pulses and starts at ~T-50 s. T90 (15-350 keV)
is 46.77 +- 7.87 sec (estimated error including systematics).

The time-averaged spectrum from T+29.77 to T+84.70 sec is best fit by
a simple power-law model.  The power law index of the time-averaged
spectrum is 2.08 +- 0.17.  The fluence in the 15-150 keV band
is 3.1 +- 0.3 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from
T+60.64 sec in the 15-150 keV band is 2.4 +- 0.6 ph/cm2/sec.
All the quoted errors are at the 90% confidence level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1071488/BA/


GRB_name: GRB210901A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30751
SUBJECT: GRB 210901A: Swift-XRT refined Analysis
DATE:    21/09/03 01:45:42 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.A. Kennea (PSU), P.A. Evans (U. Leicester), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), P. D'Avanzo (INAF-OAB), M.G.
Bernardini (INAF-OAB), E. Ambrosi  (INAF-IASFPA) , A. Tohuvavohu (U.
Toronto), B. Sbarufatti (PSU) and S. Laha report on behalf of the
Swift-XRT team:

We have analysed 2.5 ks of XRT data for GRB 210901A (Laha et al. GCN
Circ. 30746), from 139 s to 79.9 ks after the  BAT trigger. The data
comprise 126 s in Windowed Timing (WT) mode (the first 7 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The enhanced XRT position for this burst was given by Osborne et
al. (GCN Circ. 30749).

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=2.8 (+0.3, -0.4). At T+207 s  the decay
steepens to an alpha of 5.1 (+/-0.4) before breaking again at T+517 s
to a final decay with index alpha=0.60 (+/-0.09).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.55 (+0.14, -0.13). The
best-fitting absorption column is  2.8 (+/-0.4) x 10^21 cm^-2, in
excess of the Galactic value of 1.0 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.0 (+0.4, -0.3) and
a best-fitting absorption column of 1.7 (+1.2, -0.6) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.5 x 10^-11 (4.6 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.7 (+1.2, -0.6) x 10^21 cm^-2
Galactic foreground: 1.0 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:      2.0 (+0.4, -0.3)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01071488.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB210903A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30752
SUBJECT: GRB 210903A: Fermi GBM Final Real-time Localization
DATE:    21/09/03 02:00:41 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 01:50:17 UT on 3 Sep 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210903A (trigger 652326622.389106 / 210903077).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 178.6, Dec = 39.1 (J2000 degrees, equivalent to J2000 11h 54m, 39d 06'), with a statistical uncertainty of 5.4 degrees.

The angle from the Fermi LAT boresight is 102.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210903077/quicklook/glg_skymap_all_bn210903077.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210903077/quicklook/glg_healpix_all_bn210903077.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210903077/quicklook/glg_lc_medres34_bn210903077.gif


GRB_name: GRB210903B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30754
SUBJECT: GRB 210903B: Fermi GBM Final Localization
DATE:    21/09/03 16:37:03 GMT
FROM:    Joshua Wood at MSFC/Fermi-GBM  <joshua.r.wood@nasa.gov>

The Fermi GBM team reports the detection of a likely SHORT GRB

At 00:30:46.05 UT on 3 Sep 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210903B (trigger 652321851 / 210903021).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 270.9, Dec = +15.6 (J2000 degrees, equivalent to J2000 18h 03m, +15d 36'), with a statistical uncertainty of 26.1 degrees.

The angle from the Fermi LAT boresight is 66.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210903021/quicklook/glg_skymap_all_bn210903021.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210903021/quicklook/glg_healpix_all_bn210903021.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210903021/quicklook/glg_lc_medres34_bn210903021.gif


GRB_name: GRB210901A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30755
SUBJECT: GRB 210901A: GROND observations
DATE:    21/09/03 16:41:33 GMT
FROM:    Ana Nicuesa at TLS Tautenburg  <ana@tls-tautenburg.de>

A. Nicuesa Guelbenzu, S. Klose (both TLS Tautenburg), and
A. Rau (MPE Garching) report:


We observed the field of GRB 210901A (Swift trigger #1071488; Laha et al.,
GCN 30746) simultaneously in g'r'i'z'JHK with GROND mounted at the 2.2m
MPG telescope at La Silla Observatory (Chile).

Observations started at 23:43 UT on September 1, about 8.5 hr after the
GRB trigger. They were performed at an average seeing of 2.3 arcsec and at
an average airmass of 1.5.

Inside the 2.5 arcsec enhanced XRT error circle (Osborne et al., GCN
30749), we do not detect any source. Based on an observation with 23.4
minutes integration time in g'r'i'z' and 20 minutes in JHK, at a midtime
of 23:43 UT on September 1, we measure the following preliminary 3-sigma
upper limits (AB mags):

g' > 23.5,
r' > 23.6,
i' > 22.6,
J  > 20.1,
H  > 19.7, and
K  > 16.3.

We note the presence of an object at the north-western border of the XRT
error circle at coordinates RA, DEC (J2000) = 19:41:05.98, -76:55:33.0 for
which we measure r' = 21.33 +/- 0.05 mag (AB). Due to the relatively bad
seeing at present we cannot decide with certainty if this is a galaxy or a
star.

Given magnitudes are calibrated against the SkyMapper catalog (Wolf et
al., 2018, PASA 35, e010) in g'r'i'z' and 2MASS field stars in JHK
(Skrutskie et al., 2006, AJ 131, 1163).

We thank Maren Hempel for excellent support and for performing the
observations.


GRB_name: GRB210903B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30756
SUBJECT: Fermi GRB 210903B: Global MASTER-Net observations report 
DATE:    21/09/03 17:00:29 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev, O.Ershova 
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

V. Yurkov, A. Gabovich, Yu. Sergienko 
(Blagoveschensk Educational State University)




MASTER-OAFA robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 210903B ( Fermi GBM team, GCN 30754) errorbox 6219 sec after trigger time at 2021-09-03 02:14:25 UT, with upper limit up to  18.5 mag. The observations began at zenith distance = 67 deg. The sun  altitude  is -49.9 deg. 

The galactic latitude b = 17 deg., longitude l = 42 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1708736

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

    6309 | 2021-09-03 02:14:25 |         MASTER-OAFA | (18h 01m 44.08s , +25d 58m 19.7s) |   C |   180 | 18.5 |        
    6910 | 2021-09-03 02:24:26 |         MASTER-OAFA | (18h 01m 44.86s , +25d 57m 20.9s) |   C |   180 | 18.5 |        
    7310 | 2021-09-03 02:31:06 |         MASTER-OAFA | (18h 01m 47.01s , +25d 59m 20.6s) |   C |   180 | 18.5 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB210820A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30757
SUBJECT: GRB 210820A: TSHAO optical upper limit
DATE:    21/09/03 17:11:38 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI), I. Reva (FAP), A. Kusakin (FAP), A. Pozanenko (IKI), 
N.Pankov (HSE), V. Kim (FAP) report on behalf of GRB-IKI-FuN:

We observed GRB 210820A (Beardmore et al., GCN 30664) with Zeiss-1000 
telescope of Tien Shan Astronomical Observatory starting on Aug. 21 (UT) 
21:32:02.

The optical afterglow (Beardmore et al., GCN 30664; Lipunov et al., GCN 
30666; Fu et al., GCN 30669; Zhu et al., GCN 30670; Butler et al., GCN 
30672; Strausbaugh et al., GCN 30673; Blazek et al., GCN 30674; Laha et 
al., GCN 30675; LaPorte and Beardmore, GCN 30686; Komesh et al., GCN 
30688; Guelbenzu et al., GCN 30695; Kann et al., GCN 30731) was not 
detected in the stacked image down to a limiting magnitude of 21.8 in R 
filter. Preliminary photometry of the field in a stacked image is following.

Date       UT start t-T0    Filter  Exp.  OT  Err. UL(3 sigma)
                      (mid, days)     (s)
2021-08-21 21:32:02 1.17659  R      27*90 n/d n/d  21.8

The photometry is based on nearby USNO-B1.0 stars.

USNO-B1.0
RA Dec R2
01:22:01.52088 +04:35:30.2028 17.48
01:22:14.95944 +04:43:31.2204 17.89


GRB_name: GRB210903C
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30758
SUBJECT: GRB 210903C: Fermi GBM Final Real-time Localization
DATE:    21/09/03 17:37:06 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 17:26:58 UT on 3 Sep 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210903C (trigger 652382823.653196 / 210903727).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 155.0, Dec = 22.0 (J2000 degrees, equivalent to J2000 10h 20m, 22d 00'), with a statistical uncertainty of 4.2 degrees.

The angle from the Fermi LAT boresight is 72.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210903727/quicklook/glg_skymap_all_bn210903727.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210903727/quicklook/glg_healpix_all_bn210903727.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210903727/quicklook/glg_lc_medres34_bn210903727.gif


GRB_name: GRB210903A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30759
SUBJECT: Fermi GRB 210903A: Global MASTER-Net observations report 
DATE:    21/09/03 18:15:21 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev, O.Ershova 
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

V. Yurkov, A. Gabovich, Yu. Sergienko 
(Blagoveschensk Educational State University)




MASTER-Tavrida robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started inspect of the Fermi GRB 210903A ( Fermi GBM team, GCN 30752) errorbox  56033 sec after notice time and 56098 sec after trigger time at 2021-09-03 17:25:15 UT, with upper limit up to  18.6 mag. Observations started at twilight.  The observations began at zenith distance = 69 deg. The sun  altitude  is -12.8 deg. 

The galactic latitude b = 74 deg., longitude l = 164 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1708312

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

   56128 | 2021-09-03 17:25:15 |      MASTER-Tavrida | (12h 02m 08.49s , +38d 59m 08.2s) |   C |    60 | 17.6 |        
   56207 | 2021-09-03 17:26:34 |      MASTER-Tavrida | (12h 12m 24.55s , +39d 00m 39.2s) |   C |    60 | 17.8 |        
   56438 | 2021-09-03 17:30:25 |      MASTER-Tavrida | (12h 12m 59.54s , +40d 55m 06.6s) |   C |    60 | 18.1 |        
   56517 | 2021-09-03 17:31:44 |      MASTER-Tavrida | (12h 03m 33.73s , +42d 46m 35.9s) |   C |    60 | 18.0 |        
   57008 | 2021-09-03 17:39:55 |      MASTER-Tavrida | (12h 14m 34.76s , +42d 47m 02.0s) |   C |    60 | 18.3 |        
   57404 | 2021-09-03 17:46:31 |      MASTER-Tavrida | (12h 02m 01.58s , +38d 58m 43.9s) |   C |    60 | 18.5 |        
   57483 | 2021-09-03 17:47:50 |      MASTER-Tavrida | (12h 12m 26.04s , +38d 59m 03.2s) |   C |    60 | 18.6 |        
   57562 | 2021-09-03 17:49:09 |      MASTER-Tavrida | (12h 02m 26.10s , +40d 54m 08.7s) |   C |    60 | 18.5 |        
   57641 | 2021-09-03 17:50:28 |      MASTER-Tavrida | (12h 13m 03.20s , +40d 52m 36.4s) |   C |    60 | 18.5 |        
   57720 | 2021-09-03 17:51:47 |      MASTER-Tavrida | (12h 03m 41.09s , +42d 47m 32.7s) |   C |    60 | 18.5 |        
   58369 | 2021-09-03 18:02:36 |      MASTER-Tavrida | (11h 53m 47.03s , +42d 45m 34.2s) |   C |    60 | 18.3 |        
   58448 | 2021-09-03 18:03:55 |      MASTER-Tavrida | (12h 14m 40.54s , +42d 46m 09.0s) |   C |    60 | 18.5 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB210904A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30763
SUBJECT: GRB 210904A: Fermi GBM Final Real-time Localization
DATE:    21/09/04 20:58:06 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely SHORT GRB

At 20:47:39 UT on 4 Sep 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210904A (trigger 652481264.630844 / 210904866).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 121.1, Dec = -44.0 (J2000 degrees, equivalent to J2000 08h 04m, -44d 00'), with a statistical uncertainty of 9.2 degrees.

The angle from the Fermi LAT boresight is 104.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210904866/quicklook/glg_skymap_all_bn210904866.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210904866/quicklook/glg_healpix_all_bn210904866.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210904866/quicklook/glg_lc_medres34_bn210904866.gif


GRB_name: GRB210904A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30764
SUBJECT: Fermi GRB 210904A: Global MASTER-Net observations report 
DATE:    21/09/05 00:15:17 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev, O.Ershova 
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

V. Yurkov, A. Gabovich, Yu. Sergienko 
(Blagoveschensk Educational State University)




MASTER-SAAO robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in South Africa (South African Astronomical Observatory) started inspect of the Fermi GRB 210904A ( Fermi GBM team, GCN 30763) errorbox  8467 sec after notice time and 8548 sec after trigger time at 2021-09-04 23:10:08 UT, with upper limit up to  18.4 mag. The observations began at zenith distance = 81 deg. The sun  altitude  is -63.8 deg. 

The galactic latitude b = -6 deg., longitude l = 260 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1709787

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

    8579 | 2021-09-04 23:10:08 |         MASTER-SAAO | (07h 13m 56.09s , -50d 06m 24.2s) |   C |    60 | 17.5 |        
    8818 | 2021-09-04 23:14:07 |         MASTER-SAAO | (07h 19m 10.91s , -51d 59m 24.1s) |   C |    60 | 17.7 |        
    9296 | 2021-09-04 23:22:05 |         MASTER-SAAO | (07h 08m 22.61s , -48d 12m 57.4s) |   C |    60 | 17.8 |        
    9376 | 2021-09-04 23:23:25 |         MASTER-SAAO | (07h 38m 53.16s , -53d 54m 13.5s) |   C |    60 | 17.9 |        
    9536 | 2021-09-04 23:26:05 |         MASTER-SAAO | (07h 13m 58.12s , -50d 07m 33.3s) |   C |    60 | 17.8 |        
    9775 | 2021-09-04 23:30:04 |         MASTER-SAAO | (07h 19m 06.81s , -51d 59m 26.1s) |   C |    60 | 17.8 |        
    9854 | 2021-09-04 23:31:23 |         MASTER-SAAO | (07h 32m 12.17s , -51d 59m 49.4s) |   C |    60 | 17.7 |        
   10014 | 2021-09-04 23:34:03 |         MASTER-SAAO | (07h 04m 54.17s , -46d 20m 01.5s) |   C |    60 | 18.0 |        
   10253 | 2021-09-04 23:38:02 |         MASTER-SAAO | (07h 08m 27.37s , -48d 12m 23.6s) |   C |    60 | 18.1 |        
   10333 | 2021-09-04 23:39:22 |         MASTER-SAAO | (07h 20m 20.55s , -48d 12m 41.9s) |   C |    60 | 17.8 |        
   10412 | 2021-09-04 23:40:41 |         MASTER-SAAO | (07h 38m 52.71s , -53d 52m 36.0s) |   C |    60 | 18.0 |        
   10492 | 2021-09-04 23:42:01 |         MASTER-SAAO | (07h 52m 31.79s , -53d 52m 56.7s) |   C |    60 | 18.0 |        
   10651 | 2021-09-04 23:44:40 |         MASTER-SAAO | (07h 13m 59.74s , -50d 08m 01.5s) |   C |    60 | 18.1 |        
   10890 | 2021-09-04 23:48:40 |         MASTER-SAAO | (07h 19m 12.08s , -52d 00m 03.6s) |   C |    60 | 18.2 |        
   10970 | 2021-09-04 23:49:59 |         MASTER-SAAO | (07h 32m 06.04s , -52d 00m 12.5s) |   C |    60 | 18.0 |        
   11130 | 2021-09-04 23:52:39 |         MASTER-SAAO | (07h 04m 54.64s , -46d 19m 44.5s) |   C |    60 | 18.3 |        
   11369 | 2021-09-04 23:56:38 |         MASTER-SAAO | (07h 08m 23.65s , -48d 12m 55.9s) |   C |    60 | 18.4 |        
   11449 | 2021-09-04 23:57:58 |         MASTER-SAAO | (07h 20m 23.73s , -48d 13m 57.4s) |   C |    60 | 18.1 |        
   11528 | 2021-09-04 23:59:17 |         MASTER-SAAO | (07h 38m 57.95s , -53d 53m 04.8s) |   C |    60 | 18.3 |        
   11608 | 2021-09-05 00:00:37 |         MASTER-SAAO | (07h 52m 26.26s , -53d 53m 22.3s) |   C |    60 | 18.0 |        
   11691 | 2021-09-05 00:02:00 |         MASTER-SAAO | (07h 25m 12.86s , -50d 06m 49.5s) |   C |    60 | 18.2 |        
   11771 | 2021-09-05 00:03:20 |         MASTER-SAAO | (07h 37m 35.60s , -50d 07m 15.3s) |   C |    60 | 18.0 |        
   11850 | 2021-09-05 00:04:39 |         MASTER-SAAO | (07h 43m 49.99s , -51d 59m 23.6s) |   C |    60 | 17.9 |        
   11930 | 2021-09-05 00:05:59 |         MASTER-SAAO | (07h 56m 49.28s , -52d 00m 07.8s) |   C |    60 | 17.9 |        
   12010 | 2021-09-05 00:07:19 |         MASTER-SAAO | (07h 31m 08.10s , -48d 12m 41.2s) |   C |    60 | 18.1 |        
   12089 | 2021-09-05 00:08:39 |         MASTER-SAAO | (07h 43m 08.49s , -48d 11m 09.0s) |   C |    60 | 17.8 |        
   12169 | 2021-09-05 00:09:58 |         MASTER-SAAO | (07h 48m 48.15s , -50d 06m 50.2s) |   C |    60 | 17.8 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB210905A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30765
SUBJECT: GRB 210905A: Swift detection of a burst
DATE:    21/09/05 00:28:29 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

E. Sonbas (Adiyaman Univ.), E. Ambrosi (INAF-IASFPA),
A. D'Ai (INAF-IASFPA), V. D'Elia (SSDC & INAF-OAR), C. Gronwall (PSU),
S. Laha (GSFC/UMBC/CRESST), A. Y. Lien (U Tampa),
F. E. Marshall (NASA/GSFC) and D. M. Palmer (LANL) report on behalf of
the Neil Gehrels Swift Observatory Team:

At 00:12:41 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210905A (trigger=1071993).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 309.062, -44.431 which is 
   RA(J2000) = 20h 36m 15s
   Dec(J2000) = -44d 25' 50"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of at least 30 sec.  The peak count rate
was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 00:14:13.0 UT, 91.7 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 309.04815, -44.43959 which
is equivalent to:
   RA(J2000)  = 20h 36m 11.56s
   Dec(J2000) = -44d 26' 22.5"
with an uncertainty of 7.0 arcseconds (radius, 90% containment). This
location is 47 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at https://www.swift.ac.uk/sper. No
spectrum from the promptly downlinked event data is yet available to
determine the column density. 

The initial flux in the 2.5 s image was 1.23e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 250 seconds with the U filter starting
156 seconds after the BAT trigger. No credible afterglow candidate has been
found in the initial data products. The 2.7'x2.7' sub-image covers 100% of the
XRT error circle. The typical 3-sigma upper limit has been about 19.2 mag. The
8'x8' region for the list of sources generated on-board covers 100% of the XRT
error circle. The list of sources is typically complete to about 18.0 mag. No
correction has been made for the expected extinction corresponding to E(B-V) of
0.034. 

Burst Advocate for this burst is E. Sonbas (edasonbas AT yahoo.com). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)


GRB_name: GRB210905A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30766
SUBJECT: Swift GRB 210905A: Global MASTER-Net observations report 
DATE:    21/09/05 00:32:44 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev, O.Ershova 
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

V. Yurkov, A. Gabovich, Yu. Sergienko 
(Blagoveschensk Educational State University)




MASTER-SAAO robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 210905A ( E. Sonbas et al., GCN 30765) errorbox  6 sec after notice time and 414 sec after trigger time at 2021-09-05 00:19:36 UT, with upper limit up to  19.1 mag. The observations began at zenith distance = 48 deg. The sun  altitude  is -55.5 deg. 

The galactic latitude b = -37 deg., longitude l = 356 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1709881

We obtain a following upper limits.  

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

     455 |         MASTER-SAAO | P\  |    80 | 18.2 |        
     565 |         MASTER-SAAO | P\  |   300 | 19.1 |  Coadd 
     556 |         MASTER-SAAO | P\  |   100 | 18.3 |        
     678 |         MASTER-SAAO | P\  |   120 | 18.5 |        
     826 |         MASTER-SAAO | P\  |   150 | 18.5 |        


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB210901A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30767
SUBJECT: GRB 210901A: Swift/UVOT Upper Limits
DATE:    21/09/05 00:48:10 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <mhs18@psu.edu>

M. H. Siegel (PSU) and S. L. Laha (GSFC/UMBC/CRESST)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210901A
158 s after the BAT trigger (Laha et al., GCN Circ. 30746).
No optical afterglow consistent with the XRT position
(Osborne et al. GCN Circ. 30749)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           158          308          147         >20.9
u_FC               316          566          246         >19.6
white              158          974          289         >20.9
v                  646          839           39         >17.8
b                  572          764           39         >18.8
u                  316          740          265         >19.8
w1                 695          715           19         >17.8

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.200 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB210905A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30768
SUBJECT: GRB 210905A: Enhanced Swift-XRT position
DATE:    21/09/05 02:27:23 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 97 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 210905A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 309.04826, -44.43956 which is equivalent
to:

RA (J2000): 20h 36m 11.58s
Dec (J2000): -44d 26' 22.4"

with an uncertainty of 2.6 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB210905A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30769
SUBJECT: GRB 210905A: LCO Optical Detection
DATE:    21/09/05 03:00:50 GMT
FROM:    Robert Strausbaugh at U. of the Virgin Islands  <robert.strausbaugh@uvi.edu>

R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration:

We observed Swift GRB 210905A (Sonbas, et al., GCN 30765) with the LCO 1-m Sinistro instrument at the Cerro Tololo Interamerican Observatory, Chile site, on September 5, from 01:09 to 01:36 UT (corresponding to 0.95 to 1.40 hours from the GRB trigger time) with the Bessel R and I filters.

We performed a series of 3x300s exposures in R and I. In the XRT detection region (Sonbas, et al., GCN 30765) we detect an uncatalogued source in I band at the following coordinates (309.0481637, -44.4402618).  Using the USNO-B.1 catalog as reference, we calculate the following magnitudes and upper limits:

R>22.44

I=19.52+/-0.09

These magnitudes are not corrected for galactic extinction.  The detection in I and the lack of detection in R is suggestive of a high-z source.  As such additional follow-up is encouraged.  Additional LCO measurements are underway.

R.S. is funded by NSF AST grant #1831682


GRB_name: GRB210905A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30770
SUBJECT: GRB 210905A: Continued LCO Optical Observations
DATE:    21/09/05 04:33:24 GMT
FROM:    Robert Strausbaugh at U. of the Virgin Islands  <robert.strausbaugh@uvi.edu>

R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration:

We observed Swift GRB 210905A (Sonbas, et al., GCN 30765) with the LCO 1-m Sinistro instrument at the Cerro Tololo Interamerican Observatory, Chile site, on September 5, from 02:32 to 02:53 UT (corresponding to 2.37 to 2.72 hours from the GRB trigger time) with the Bessel I filter.

We performed a series of 5x300s exposures in I band. We detect the same uncataloged source (Strausbaugh, et al., GCN 30769) at the following coordinates (309.0481637, -44.4402618).  Using the USNO-B.1 catalog as reference, we calculate the following magnitude:

I=20.4+/-0.1

These magnitudes are not corrected for galactic extinction.  There is clear evidence of fading from the first epoch (I=19.52+/-0.09) providing strong evidence that this is the afterglow of this burst.

R.S. is funded by NSF AST grant #1831682


GRB_name: GRB210905A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30771
SUBJECT: GRB 210905A: VLT/X-shooter spectroscopic redshift
DATE:    21/09/05 06:06:26 GMT
FROM:    Andrea Rossi at INAF  <andrea.rossi@inaf.it>

N. Tanvir (Univ. Leicester), A. Rossi (INAF-OAS), D. Xu (NAOC), Z.P. Zhu 
(NAOC,HUST), L. Izzo (DARK/NBI), D. A. Kann (HETH/IAA-CSIC), and A.J. 
Levan (Radboud) report on behalf of the Stargate collaboration:

We observed the location of the afterglow (Strausbaugh & Cucchiara, GCN 
30769, 30770) of GRB 210905A (Sonbas et al., GCN 30765) using the ESO 
VLT UT3 (Melipal) equipped with the X-shooter spectrograph. Our spectra 
cover the wavelength range 3000-21000 AA, and consist of 4 exposures by 
1200 s each. Our observations started on 2021 September 05 at 02:44 UT, 
~2.53 hours after the GRB detection.

In the acquisition image obtained between 2.53 and 2.73 hours after the 
burst, the afterglow is well detected at I and z-bands, but not in the 
r-band, confirming the red color already noted by Strausbaugh & 
Cucchiara. We measure the following AB magnitudes:

r>23.5
I=20.3+-0.1
z=19.4+-0.1

Spectroscopy of the source reveals a continuum well detected in the red 
part of visible arm. A clear break is detected around 9000AA which we 
interpret as the Lyman-alpha break at z = 6.318, and explains the strong 
r-z color as due to Lyman dropout. Other lines such as Fe II, Al II, C 
IV and Si II are visible and display a double absorption profile, which 
is possibly due to different intervening systems at z1 = 6.312 and z2 = 
6.318. We thus conclude that z=6.318 is the redshift of GRB 210905A. 
Further analysis is undergoing.

We acknowledge support from the ESO observing staff at Paranal, in 
particular Israel Blanchard, Michael Abdul-Masih, and Matias Jones.


GRB_name: GRB210905A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30772
SUBJECT: GRB 210905A: REM NIR afterglow detection
DATE:    21/09/05 07:42:23 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <pda.davanzo@gmail.com>

P. D'Avanzo, A. Melandri, S. Covino, D. Fugazza (INAF-OAB), on behalf of the REM team, report:

We observed the field of GRB 210905A (Sonbas, et al., GCN 30765) with the REM 60cm robotic telescope 
located at the ESO premise of La Silla (Chile). The observations were carried in the g, r, i, z, J, H and K bands, 
starting on 2021 September 05 at 00:19:49 UT (i.e. 428 seconds after the burst) and lasting for about three hours. 

At the position of the optical afterglow (Strausbaugh & Cucchiara, GCN Circ. 30769) we detected an uncatalogued 
source in all NIR bands. From preliminary photometry we derive the following magnitude: 

H = 14.82  +/- 0.15 
(Vega; calibrated against the 2MASS catalogue) 

at a mid time of t-t0 = 469 seconds.


GRB_name: GRB210905A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30773
SUBJECT: GRB 210905A: DECam Detection
DATE:    21/09/05 11:56:22 GMT
FROM:    Dougal Dobie at VAST  <ddobie94@gmail.com>

J. Cooke (Swinburne), S. Webb (Swinburne), D. Dobie (Swinburne),
J. Zhang (Swinburne), S. Hegarty (Swinburne), A. Moller (Swinburne),
S. Goode (Swinburne), R. Strausbaugh (U. of the Virgin Islands),
Tim Abbott (NOIRLab), Vivek Gupta (Swinburne), Mark Suhr (Swinburne)

We observed Swift GRB 210905A (Sonbas, et al., GCN 30765) with the
Dark Energy Camera (DECam) at Cerro Tololo Inter-American Observatory.
We performed 3x60s exposures with the i filter on September 5, from
04:46:10 to 04:50:09 UT.

We make a marginal detection of a source at the position reported by
Strausbaugh et al. (GCN 30769) with i=23.6. This measurement is not
corrected for galactic extinction.


GRB_name: GRB210827B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30774
SUBJECT: GRB 210827B: GECAM detection
DATE:    21/09/05 15:56:03 GMT
FROM:    Y Q Zhang at IHEP  <yqzhang@ihep.ac.cn>

J. C. Liu, S. L. Xiong, X. Y. Zhao, Y. Huang, X. Y. Song, C. Cai, S. Xiao,
S. L. Xie, Y. Q. Zhang, Y. Zhao, Z. W. Guo, C. Zheng, W. C. Xue, C. Y. Li,
C. W. Wang, Q. B. Yi, B. X. Zhang, P. Zhang, W. X. Peng, R. Qiao, D. Y. Guo,
X. B. Li, X. Ma, P. Wang, J. Wang, Z. Zhang, S. J. Zheng, W. Chen, J. J. He, 
G. Y. Zhao, Y. Q. Du, H. Wu, J. Liang, Q. Luo, X. L. Zhang,
L. M. Song, F. J. Lu, S. N. Zhang (IHEP), report on behalf of GECAM team:

During the commissioning phase, GECAM-B was triggered in-flight by a long
burst, GRB 210827B, at 2021-08-27T10:10:16.60 UTC (denoted as T0), 
which was also observed by Fermi/GBM (GCN #30726). 
GECAM alert data was downlinked to the ground through the short message
service of BeiDou Navigation Satellite System (BDS) within ~60 s after T0.

According to the BDS alert data, this burst mainly consists of a broad pulse
with a duration of about 20 s. 

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_lc_grd_all_combine_83758216.png

Using the automatic on-ground localization pipeline with the BDS alert data, 
GECAM-B localized this burst to the following position (J2000): 
Ra: 307.5 deg 
Dec: -19.2 deg
Err: 3.5 deg (1-sigma, statistical only)
The current systematic error of location is estimated to be several degrees 
which could be minimized by the ongoing calibration.

The GECAM preliminary location could be found here: 
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_skymap_bdm_83758216_V01.png

GECAM location is consistent with the Fermi/GBM position within the error.

Please note that all GECAM results here are preliminary. The final analysis
will be published in journal papers or GECAM online catalog.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor
(GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in
Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time),
which was funded by the Chinese Academy of Sciences (CAS).


GRB_name: GRB210610A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30775
SUBJECT: GRB 210610A: Maidanak and AbAO optical observations
DATE:    21/09/05 23:23:17 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI), A. Pozanenko (IKI), O. Burhonov (UBAI), R. Ya. 
Inasaridze (AbAO),  N. Pankov (IKI), V. R. Ayvazian (AbAO),  D. 
Datashvili (AbAO), G. V. Kapanadze (AbAO), Sh. Ehgamberdiev (UBAI) 
report on behalf of IKI-GRB-FuN:

We observed the field of GRB 210610A (Page et al., GCN  30160) with 
AZT-22 telescope of Maidanak Observatory and AS-32 telescope of 
Abastumani observatory (AbAO). The optical afterglow (Page et al., GCN 
30160; Hosokawa et al., GCN 30161; Xu et a., GCN 30162; Kumar et al., 
GCN 30163; Lipunov et al., GCN 30166; de Wet et al., GCN 30168; Hosokawa 
et al., GCN 30169; Sun et al., GCN 30185; Watson et al., GCN 30191; 
Zheng et al., GCN 30203; Kann et al., GCN 30211; Belkin et al., GCN 
30214; Moskvitin et al., GCN 30229; Kann et al., GCN 30232; Siegel et 
al., GCN 30246) is clearly detected in the stacked images. Preliminary 
photometry of the afterglow is following.

Date UT start t-T0 Filter Exp. OT UL(3sigma) Telescope
                         (mid, days) (s)

2021-06-10 17:57:56 0.14529 R 14*300 19.62 0.03 24.0 AZT-22
2021-06-10 20:24:59 0.23769 R 42*60  20.46 0.25 20.6 AS-32
2021-06-12 16:34:08 2.07494 R 7*300  23.09 0.20 23.5 AZT-22
2021-06-13 16:44:01 3.09049 R 12*300 23.77 0.21 24.4 AZT-22
2021-06-14 17:25:22 4.11920 R 12*300 24.08 0.28 24.4 AZT-22

Photometry is based on the SDSS-DR12 nearby stars (Lupton transformations).
SDSS-DR12_id RA DEC R(Lupton)
J133717.13+142854.9 204.32139900 +14.48192200 17.0295
J133703.62+142832.7 204.26512000 +14.47576300 17.7239

Using our data in the R filter, it was found that the light curve can be 
described by a broken power-law with power law indices of -0.82 and 
-1.39. The break time is 0.23+/-0.17 days. These values are consistent 
with the result reported by Kann et al. (GCN 30211).

The light curve can be found at
http://grb.rssi.ru/GRB210610A/GRB210610A_LC.png


GRB_name: GRB210905A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30776
SUBJECT: GRB 210905A: Swift-XRT refined Analysis
DATE:    21/09/06 01:28:59 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), E. Ambrosi 
(INAF-IASFPA) , M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR),
B. Sbarufatti (PSU), D.N. Burrows (PSU), J. D. Gropp (PSU), P.A. Evans
(U. Leicester) and E. Sonbas report on behalf of the Swift-XRT team:

We have analysed 5.7 ks of XRT data for GRB 210905A (Sonbas et al. GCN
Circ. 30765), from 82 s to 84.8 ks after the  BAT trigger. The data
comprise 209 s in Windowed Timing (WT) mode (the first 8 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The enhanced XRT position for this burst was given by Beardmore
et al. (GCN Circ. 30768).

The late-time light curve (from T0+3.8 ks) can be modelled with a
power-law decay with a decay index of alpha=1.19 (+0.26, -0.27).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.44 (+0.05, -0.04). The
best-fitting absorption column is  3.8 (+1.8, -1.7) x 10^22 cm^-2, at a
redshift of 6.318, in addition to the Galactic value of 3.4 x 10^20
cm^-2 (Willingale et al. 2013). The PC mode spectrum has a photon index
of 1.90 (+/-0.13) and a best-fitting absorption column of 2.9 (+3.7,
-2.9) x 10^22 cm^-2. The counts to observed (unabsorbed) 0.3-10 keV
flux conversion factor deduced from this spectrum  is 3.4 x 10^-11 (3.9
x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Galactic foreground: 3.4 x 10^20 cm^-2
Intrinsic column:    2.9 (+3.7, -2.9) x 10^22 cm^-2 at z=6.318
Photon index:      1.90 (+/-0.13)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01071993.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB210905A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30779
SUBJECT: Fermi GBM Sub-Threshold Detection of GRB 210905A
DATE:    21/09/06 05:39:59 GMT
FROM:    Peter Veres at UAH  <veresp@gmail.com>

P. Veres (UAH) and O. J. Roberts (USRA) report
on behalf of the Fermi-GBM Team:

"Swift-BAT detected GRB 210905A at 00:12:41 UT (GCN 30765). There was no
Fermi-GBM onboard trigger around the event.

The GBM targeted search [1], the most sensitive, coherent search for
GRB-like signals was run from +/-30 s around the BAT trigger time.  A
transient source was identified whose most significant timescale according
to the search is 8.192 s with a false alarm rate of 1.3e-5 Hz, and a
location consistent with the Swift-BAT event, using the standard search
protocol with a S/N of 13.  The GBM targeted search event was found with
the highest significance with a "normal" spectral template (Band function
with Epeak = 230 keV, alpha = -1.0, beta = -2.3).

The GBM light curve consists of multiple overlapping pulses. The
time-averaged spectrum from T0-26 s to T0+16 s is best fit by a power law
function with an exponential high-energy cutoff (T0 is 2021-09-05 00:12:41
UT). The power law index is -1.19 +/- 0.13 and the cutoff energy,
parameterized as Epeak, is 204 +/- 45 keV.

The event fluence (10-1000 keV) in this time interval for the best fitting
model is (6.08 +/- 0.59)E-6 erg/cm^2. Using the redshift z=6.318 reported
by Tanvir et al. (GCN 30771), we derive an isotropic equivalent energy in
the 1-10,000 keV range of (4.25 +/- 0.41)E+53 erg.

This analysis is preliminary.

[1] Goldstein et al. 2019 arXiv:1903.12597
"


GRB_name: GRB210905A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30780
SUBJECT: Konus-Wind detection of GRB 210905A
DATE:    21/09/06 15:08:33 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

D. Frederiks, S. Golenetskii, A.Lysenko, D. Svinkin,
A. Ridnaya, A. Tsvetkova,  M. Ulanov, and T. Cline, report:

The long GRB GRB 210905A (Swift-BAT detection: Sonbas et al., GCN 30765;
Fermi GBM Sub-Threshold Detection: Veres & Roberts, GCN 30779),
T0 (BAT) = 00:12:41, was detected by Konus-Wind (KW) in the waiting mode.

A Bayesian block analysis of the KW waiting mode data in reveals
two major emission episodes, separated by ~750 s.
The first episode, from ~T0-25.5s to ~t0+13 s, corresponds to the BAT and GBM detections;
and the second episode, from ~T0-750 s to ~t0+870 s, corresponds to a bright flare visible
in the XRT light curve (https://www.swift.ac.uk/xrt_curves/01071993/ ).

The KW light curve of this burst is available
at http://www.ioffe.ru/LEA/GRBs/GRB210905A/

Modeling the KW 3-channel spectrum of the first episode
by a power law with exponential cutoff (CPL) model
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
yields alpha = -1.45 (-0.24, + 0.38) and Ep = 203 (-58,+111) keV.
The spectrum of the second episode can be described by a CPL
with alpha = -0.88 (-0.30, + 0.76) and Ep = 167 (-61,+88) keV.

In the 10 keV -10 MeV band, standard for the KW analysis,
the total burst fluence is (1.7 Â± 0.7)x10^-5 erg/cm^2,
and the 2.944 s peak energy flux is (3.6 Â± 0.7)x10^-7 erg/cm^2.

Assuming the redshift z=6.318 (Tanvir et al., GCN 30771)
and a standard cosmology with H_0 = 67.3 km/s/Mpc, Omega_M = 0.315,
and Omega_Lambda = 0.685 (Planck Collaboration, 2014),
we estimate the isotropic energy release E_iso to ~1.1x10^54 erg,
the isotropic luminosity L_iso to ~1.7x10^53 erg/s,
and the rest-frame peak energy of the time-integrated spectrum Ep,z to ~1300 keV.
With these values, GRB 210905A lies within 68% prediction bands for
for both 'Amati' and 'Yonetoku' relations for the sample of >300 long KW GRBs
with known redshifts (Tsvetkova et al., 2021, ApJ, 908, 83),
see http://www.ioffe.ru/LEA/GRBs/GRB210905A/GRB210905A_rest_frame.pdf

All the quoted errors are estimated at the 68% confidence level.
All the presented results are preliminary.


GRB_name: GRB210905A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30781
SUBJECT: GRB 210905A, GROND observations
DATE:    21/09/06 17:04:00 GMT
FROM:    Sylvio Klose at TLS Tautenburg  <klose@tls-tautenburg.de>

A. Nicuesa Guelbenzu, S. Klose (both TLS Tautenburg), and A. Rau (MPE 
Garching) report:

We observed the field of GRB 210905A (Swift trigger #1071993; Sonbas et 
al., GCN 30765) simultaneously in g'r'i'z'JHK with GROND mounted at the 
2.2m MPG telescope at La Silla Observatory (Chile).

Observations started at 23:35 UT on September 5, about 23.2 hr after the 
GRB trigger. They were performed at an average seeing of 1.7 arcsec and at 
an average airmass of 1.2.

Based on combined images with 22 min total exposure in g'r'i'z' and 25 min 
in JHK, at a mid-time of 23:55 UT on 2021-09-05 for the afterglow 
(Strausbaugh & Cucchiara GCN 30769 and 30770; Tanvir et al., GCN 30771; 
D'Avanzo et al., GCN 30772; Dobie et al., GCN 30773) we derive the 
following preliminary AB magnitudes and 3-sigma upper limits:

g' > 24.3,
r' > 24.3,
i' > 23.8,
z' = 21.6 +/- 0.2,
J  = 20.2 +/- 0.2,
H  = 20.1 +/- 0.2,
K  > 18.2.

Given magnitudes are calibrated against the SkyMapper catalog (Wolf et 
al., 2018, PASA 35, e010) in g'r'i'z' and 2MASS field stars in JHK 
(Skrutskie et al., 2006, AJ 131, 1163).

We thank Maren Hempel and Regis Lachaume for excellent support and for 
performing the observations.


GRB_name: GRB210905A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30782
SUBJECT: GRB 210905A: AstroSat CZTI detection
DATE:    21/09/07 15:35:29 GMT
FROM:    Gaurav Waratkar at IIT,Bombay  <gauravwaratkar@iitb.ac.in>

V. Prasad (IUCAA), P. Sawant (IUCAA), G. Waratkar (IITB), A. Vibhute
(IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao
(IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat
CZTI collaboration:

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al.,
2021, JApA, 42, 73) showed detection of a long GRB 210905A, which was
also detected by Swift-BAT (Sonbas et al., GCN 30765) and a
sub-threshold detection in Fermi-GBM (Veres & Roberts, GCN 30779).

The source was clearly detected in the 20-200 keV energy range. The
light curve showed multiple peaks of emission with the strongest peak at
2021-09-05 00:12:40.5 UT. The measured peak count rate associated with
the burst is 87 (+37.9, -7) cts/s above the background in the combined
data of two quadrants (out of four), with a total of 1092 (+250, -294)
cts. The local mean background count rate was 286.0 (+2, -2) cts/s.
Using cumulative rates, we measure a T90 of 24 (+11, -7) s.

CZTI GRB detections are reported regularly on the payload site at
http://astrosat.iucaa.in/czti/?q=grb [1]. CZTI is built by a TIFR-led
consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC
and PRL. The Indian Space Research Organisation funded, managed and
facilitated the project. 

Links:
------
[1] http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB210905A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30783
SUBJECT: GRB 210905A: ALMA detection
DATE:    21/09/07 23:00:31 GMT
FROM:    Tanmoy Laskar at U of Bath  <tanmoylaskar@gmail.com>

T. Laskar (University of Bath), K. D. Alexander (Northwestern), R. Margutti
(Berkeley), E. Berger (Harvard), W. Fong (Northwestern), R. Chornock
(Berkeley), C. G. Mundell (University of Bath), and P. Schady (University
of Bath) report on behalf of a larger collaboration:

"We observed GRB 210905A (Sonbas et al. GCN 30765) with the Atacama Large
Millimeter/Submillimeter Array (ALMA) at 97.5 GHz beginning on 2021
September 05 23:41 UT (0.98 days after the burst).

Preliminary analysis reveals a mm source with flux density of ~ 0.1 mJy at
position:

RA (J2000) = 20:36:11.5685 (+/- 0.0002)
Dec (J2000) = -44:26:24.840 (+/- 0.002)

consistent with the X-ray position (Beardmore et al., GCN 30768) and
optical position (Strausbaugh & Cucchiara, GCN 30769).

We thank the JAO staff, AoD, P2G, and the entire ALMA team for their help
with these observations."


GRB_name: GRB210905A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30784
SUBJECT: GRB 210905A: ATCA detection
DATE:    21/09/08 23:15:54 GMT
FROM:    Tanmoy Laskar at U of Bath  <tanmoylaskar@gmail.com>

T. Laskar (University of Bath), S. Bhandari (CSIRO), R. Margutti (UC
Berkeley), K. D. Alexander (Northwestern), E. Berger (Harvard), R. Chornock
(UC Berkeley), D. Coppejans (Northwestern), M. Drout (U. Toronto), H. van
Eerten (University of Bath), W. Fong (Northwestern), C. Guidorzi (U.
Ferrara), C. G. Mundell (University of Bath), P. Schady (University of
Bath), and G. Schroeder (Northwestern) report:

"We observed GRB 210905A (Sonbas et al., GCN 30765) with the Australia
Telescope Compact Array (ATCA) at multiple frequencies beginning on 2021
Sep 08 14:20 UT. We detect a radio counterpart at 5.5 and 9.0 GHz at a
position consistent with the X-ray position (Beardmore et al., GCN 30768),
optical position (Strausbaugh & Cucchiara, GCN 30769), and mm-band position
(Laskar et al., GCN 30783) with a flux density of ~ 0.1 mJy at 9.0 GHz at a
mid-time of 3.65 days after the burst.

We thank the CSIRO staff for approving and scheduling these observations.

The Australia Telescope Compact Array is part of the Australia Telescope
National Facility which is funded by the Australian Government for
operation as a National Facility managed by CSIRO. We acknowledge the
Gomeroi people as the traditional owners of the Observatory site."


GRB_name: GRB210905A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30785
SUBJECT: GRB 210905A: Swift/UVOT Upper Limits
DATE:    21/09/09 04:59:53 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <mhs18@psu.edu>

M. H. Siegel (PSU) and E. Sonbas (Adiyaman Univ.)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210905A
157 s after the BAT trigger (Sonbas et al., GCN Circ. 30765).
No optical afterglow consistent with the XRT position
(Beardmore et al. GCN Circ. 30768) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

u_FC               157          407          246         >20.1
v                 4193         4393          197         >19.3
b                 3782         3982          197         >21.4
w1                4603         4803          197         >20.1
m2                4398         4597          197         >19.5
w2                3988         4188          197         >19.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.034 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB210909A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30786
SUBJECT: GRB 210909A: Fermi GBM Final Real-time Localization
DATE:    21/09/09 10:53:27 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely SHORT GRB

At 10:43:19 UT on 9 Sep 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210909A (trigger 652877004.365114 / 210909447).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 140.6, Dec = 83.3 (J2000 degrees, equivalent to J2000 09h 22m, 83d 17'), with a statistical uncertainty of 2.7 degrees.

The angle from the Fermi LAT boresight is 88.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210909447/quicklook/glg_skymap_all_bn210909447.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210909447/quicklook/glg_healpix_all_bn210909447.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210909447/quicklook/glg_lc_medres34_bn210909447.gif


GRB_name: GRB210909A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30788
SUBJECT: Fermi GRB 210909A: Global MASTER-Net observations report 
DATE:    21/09/09 17:30:49 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev, O.Ershova 
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

V. Yurkov, A. Gabovich, Yu. Sergienko 
(Blagoveschensk Educational State University)




MASTER-Kislovodsk robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 210909A ( Fermi GBM team, GCN 30786) errorbox  20793 sec after notice time and 20835 sec after trigger time at 2021-09-09 16:30:34 UT, with upper limit up to  18.9 mag. Observations started at twilight.  The observations began at zenith distance = 51 deg. The sun  altitude  is -11.3 deg. 

MASTER-Tavrida robotic telescope  located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started inspect of the Fermi GRB 210909A errorbox  22297 sec after notice time and 22338 sec after trigger time at 2021-09-09 16:55:38 UT, with upper limit up to  18.3 mag. Observations started at twilight.  The observations began at zenith distance = 53 deg. The sun  altitude  is -9.8 deg. 

The galactic latitude b = 31 deg., longitude l = 129 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1714989

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

   20865 | 2021-09-09 16:30:34 |   MASTER-Kislovodsk | (10h 14m 28.70s , +82d 47m 53.6s) |   C |    60 | 16.3 |        
   20865 | 2021-09-09 16:30:34 |   MASTER-Kislovodsk | (09h 41m 16.73s , +83d 05m 01.4s) |   C |    60 | 17.1 |        
   20945 | 2021-09-09 16:31:54 |   MASTER-Kislovodsk | (08h 23m 41.35s , +84d 39m 01.6s) |   C |    60 | 16.6 |        
   20946 | 2021-09-09 16:31:54 |   MASTER-Kislovodsk | (07h 38m 58.88s , +84d 54m 26.6s) |   C |    60 | 17.3 |        
   21026 | 2021-09-09 16:33:15 |   MASTER-Kislovodsk | (08h 12m 17.57s , +82d 43m 50.6s) |   C |    60 | 16.5 |        
   21026 | 2021-09-09 16:33:15 |   MASTER-Kislovodsk | (07h 40m 00.71s , +83d 01m 22.3s) |   C |    60 | 17.2 |        
   21106 | 2021-09-09 16:34:35 |   MASTER-Kislovodsk | (09h 42m 52.34s , +80d 51m 36.6s) |   C |    60 | 16.7 |        
   21106 | 2021-09-09 16:34:35 |   MASTER-Kislovodsk | (09h 17m 11.18s , +81d 09m 45.3s) |   C |    60 | 17.5 |        
   21186 | 2021-09-09 16:35:55 |   MASTER-Kislovodsk | (08h 06m 09.13s , +80d 51m 24.3s) |   C |    60 | 16.9 |        
   21186 | 2021-09-09 16:35:55 |   MASTER-Kislovodsk | (07h 40m 44.78s , +81d 09m 58.0s) |   C |    60 | 17.6 |        
   21266 | 2021-09-09 16:37:15 |   MASTER-Kislovodsk | (11h 10m 25.24s , +84d 40m 57.4s) |   C |    60 | 17.0 |        
   21266 | 2021-09-09 16:37:15 |   MASTER-Kislovodsk | (10h 24m 16.27s , +84d 54m 54.2s) |   C |    60 | 17.8 |        
   21347 | 2021-09-09 16:38:36 |   MASTER-Kislovodsk | (08h 48m 42.49s , +86d 34m 16.5s) |   C |    60 | 17.1 |        
   21347 | 2021-09-09 16:38:36 |   MASTER-Kislovodsk | (07h 36m 57.06s , +86d 43m 45.6s) |   C |    60 | 18.0 |        
   21427 | 2021-09-09 16:39:56 |   MASTER-Kislovodsk | (09h 22m 34.63s , +78d 57m 41.8s) |   C |    60 | 17.1 |        
   21427 | 2021-09-09 16:39:56 |   MASTER-Kislovodsk | (09h 01m 28.93s , +79d 16m 31.4s) |   C |    60 | 17.9 |        
   21507 | 2021-09-09 16:41:16 |   MASTER-Kislovodsk | (11h 19m 46.37s , +80d 54m 45.8s) |   C |    60 | 17.0 |        
   21507 | 2021-09-09 16:41:16 |   MASTER-Kislovodsk | (10h 53m 28.11s , +81d 12m 50.5s) |   C |    60 | 17.9 |        
   21587 | 2021-09-09 16:42:36 |   MASTER-Kislovodsk | (10h 21m 26.17s , +79d 17m 57.3s) |   C |    60 | 18.1 |        
   21667 | 2021-09-09 16:43:56 |   MASTER-Kislovodsk | (11h 43m 38.91s , +83d 04m 51.6s) |   C |    60 | 18.1 |        
   21827 | 2021-09-09 16:46:36 |   MASTER-Kislovodsk | (10h 14m 37.26s , +82d 47m 18.5s) |   C |    60 | 17.1 |        
   21827 | 2021-09-09 16:46:36 |   MASTER-Kislovodsk | (09h 41m 27.54s , +83d 03m 49.6s) |   C |    60 | 18.3 |        
   21908 | 2021-09-09 16:47:56 |   MASTER-Kislovodsk | (08h 23m 51.07s , +84d 38m 06.6s) |   C |    60 | 17.3 |        
   21908 | 2021-09-09 16:47:56 |   MASTER-Kislovodsk | (07h 39m 11.29s , +84d 53m 15.1s) |   C |    60 | 18.3 |        
   21988 | 2021-09-09 16:49:17 |   MASTER-Kislovodsk | (08h 12m 33.75s , +82d 45m 28.3s) |   C |    60 | 17.1 |        
   21988 | 2021-09-09 16:49:17 |   MASTER-Kislovodsk | (07h 40m 03.60s , +83d 02m 47.9s) |   C |    60 | 18.1 |        
   22068 | 2021-09-09 16:50:37 |   MASTER-Kislovodsk | (09h 42m 51.64s , +80d 51m 47.2s) |   C |    60 | 17.3 |        
   22068 | 2021-09-09 16:50:37 |   MASTER-Kislovodsk | (09h 17m 06.72s , +81d 09m 47.4s) |   C |    60 | 18.5 |        
   22148 | 2021-09-09 16:51:57 |   MASTER-Kislovodsk | (07h 40m 48.78s , +81d 10m 07.3s) |   C |    60 | 18.2 |        
   22148 | 2021-09-09 16:51:57 |   MASTER-Kislovodsk | (08h 06m 15.07s , +80d 51m 34.7s) |   C |    60 | 17.3 |        
   22228 | 2021-09-09 16:53:17 |   MASTER-Kislovodsk | (11h 10m 34.85s , +84d 41m 30.5s) |   C |    60 | 17.2 |        
   22228 | 2021-09-09 16:53:17 |   MASTER-Kislovodsk | (10h 24m 21.62s , +84d 55m 25.0s) |   C |    60 | 18.4 |        
   22309 | 2021-09-09 16:54:38 |   MASTER-Kislovodsk | (08h 49m 05.00s , +86d 32m 02.9s) |   C |    60 | 17.3 |        
   22309 | 2021-09-09 16:54:38 |   MASTER-Kislovodsk | (07h 38m 03.19s , +86d 42m 03.9s) |   C |    60 | 18.5 |        
   22369 | 2021-09-09 16:55:38 |      MASTER-Tavrida | (06h 55m 26.00s , +82d 42m 36.7s) |   C |    60 | 16.4 |        
   22389 | 2021-09-09 16:55:58 |   MASTER-Kislovodsk | (09h 22m 47.49s , +78d 56m 52.4s) |   C |    60 | 17.4 |        
   22389 | 2021-09-09 16:55:58 |   MASTER-Kislovodsk | (09h 01m 42.46s , +79d 15m 41.5s) |   C |    60 | 18.3 |        
   22469 | 2021-09-09 16:57:18 |   MASTER-Kislovodsk | (11h 19m 54.63s , +80d 53m 59.4s) |   C |    60 | 17.2 |        
   22469 | 2021-09-09 16:57:18 |   MASTER-Kislovodsk | (10h 53m 37.55s , +81d 11m 58.5s) |   C |    60 | 18.4 |        
   22550 | 2021-09-09 16:58:38 |   MASTER-Kislovodsk | (10h 21m 29.34s , +79d 16m 51.5s) |   C |    60 | 18.6 |        
   22630 | 2021-09-09 16:59:58 |   MASTER-Kislovodsk | (11h 43m 39.94s , +83d 05m 55.2s) |   C |    60 | 18.4 |        
   22790 | 2021-09-09 17:02:39 |   MASTER-Kislovodsk | (09h 41m 32.34s , +83d 03m 39.8s) |   C |    60 | 18.5 |        
   22790 | 2021-09-09 17:02:39 |   MASTER-Kislovodsk | (10h 14m 43.09s , +82d 47m 07.3s) |   C |    60 | 17.3 |        
   22870 | 2021-09-09 17:03:59 |   MASTER-Kislovodsk | (07h 39m 26.26s , +84d 53m 54.7s) |   C |    60 | 18.4 |        
   22870 | 2021-09-09 17:03:59 |   MASTER-Kislovodsk | (08h 24m 14.18s , +84d 38m 32.4s) |   C |    60 | 17.4 |        
   22951 | 2021-09-09 17:05:19 |   MASTER-Kislovodsk | (07h 40m 17.83s , +83d 00m 58.2s) |   C |    60 | 18.2 |        
   22951 | 2021-09-09 17:05:19 |   MASTER-Kislovodsk | (08h 12m 42.35s , +82d 43m 28.0s) |   C |    60 | 17.2 |        
   23031 | 2021-09-09 17:06:40 |   MASTER-Kislovodsk | (07h 41m 27.45s , +83d 01m 00.4s) |   C |    60 | 15.4 |        
   23031 | 2021-09-09 17:06:40 |   MASTER-Kislovodsk | (08h 13m 26.89s , +82d 43m 28.5s) |   C |    60 | 14.3 |        
   23111 | 2021-09-09 17:08:00 |   MASTER-Kislovodsk | (07h 42m 25.79s , +83d 01m 02.0s) |   C |    60 | 15.2 |        
   23111 | 2021-09-09 17:08:00 |   MASTER-Kislovodsk | (08h 14m 51.39s , +82d 43m 31.1s) |   C |    60 | 14.5 |        
   23191 | 2021-09-09 17:09:20 |   MASTER-Kislovodsk | (11h 10m 37.44s , +84d 40m 37.1s) |   C |    60 | 17.4 |        
   23191 | 2021-09-09 17:09:20 |   MASTER-Kislovodsk | (10h 24m 33.41s , +84d 54m 34.9s) |   C |    60 | 18.5 |        
   23272 | 2021-09-09 17:10:40 |   MASTER-Kislovodsk | (08h 49m 39.01s , +86d 33m 30.5s) |   C |    60 | 17.4 |        
   23272 | 2021-09-09 17:10:40 |   MASTER-Kislovodsk | (07h 38m 03.59s , +86d 43m 53.2s) |   C |    60 | 18.6 |        
   23352 | 2021-09-09 17:12:00 |   MASTER-Kislovodsk | (09h 22m 46.92s , +78d 57m 13.9s) |   C |    60 | 17.5 |        
   23352 | 2021-09-09 17:12:00 |   MASTER-Kislovodsk | (09h 01m 41.45s , +79d 16m 06.2s) |   C |    60 | 18.6 |        
   23431 | 2021-09-09 17:13:20 |   MASTER-Kislovodsk | (11h 19m 55.59s , +80d 54m 05.9s) |   C |    60 | 17.5 |        
   23431 | 2021-09-09 17:13:20 |   MASTER-Kislovodsk | (10h 53m 39.60s , +81d 12m 03.4s) |   C |    60 | 18.6 |        
   23512 | 2021-09-09 17:14:40 |   MASTER-Kislovodsk | (10h 21m 38.29s , +79d 17m 13.7s) |   C |    60 | 18.9 |        
   23592 | 2021-09-09 17:16:00 |   MASTER-Kislovodsk | (11h 43m 46.21s , +83d 03m 59.1s) |   C |    60 | 18.6 |        
   24005 | 2021-09-09 17:22:54 |      MASTER-Tavrida | (06h 40m 04.63s , +84d 43m 17.7s) |   C |    60 | 18.3 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB210619B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30791
SUBJECT: GRB 210619B: Maidanak and Assy optical observations, broken power law parametrization
DATE:    21/09/09 21:25:26 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI),  A. Pozanenko (IKI), O. Burhonov (UBAI), V. Kim (FAI, 
HSE), M. Krugov (FAI), N. Pankov (HSE), Sh. Ehgamberdiev (UBAI),  report 
on behalf of IKI-GRB-FuN:

We observed the field of GRB 210619B (D'Avanzo et al. GCN 30261) with 
AZT-22 telescope of Maidanak Observatory and AZT-20 telescope of 
Assy-Turgen observatory. The optical afterglow (D'Avanzo et al. GCN 
30261; Jelinek et al., GCN 30263; Kong, GCN 30265; Pellegrin et al., GCN 
30268; Perley, GCN 30271; Zheng and Filippenko, GCN 30273; Blazek et 
al., GCN 30274; Kann et al., GCN 30275; Xin et al., GCN 30277; Kiun et 
al., GCN 30278; Shrestha et al., GCN 30280; Jelkinek et al., GCN 30281; 
Kumar et al., GCN 30286; D'Avanzo et al., GCN 30288; Moskvitin and 
Maslennikova, GCN 303291; Romanov, GCN 30292; Hu et al., GCN 30293; Zhu 
et al., GCN 30294; Belkin et al., GCN 30299; Moskvitin and Maslennikova, 
GCN 30303; Romanov and Lane, GCN 30305; Moskvitin and Maslennikova, GCN 
30309; Vinko et al., GCN 30320; Kann et al., GCN 30338; Zaznobin et al., 
GCN 30343) is clearly detected on the most of stacked images. 
Preliminary photometry of the afterglow of some of observations is 
following.

Date UT start t-T0 Filter Exp. OT UL(3sigma) Telescope
                         (mid, days) (s)

2021-06-20 19:02:53 0.79963  R 8*300  19.47 0.06 23.0 AZT-22
2021-06-21 19:53:41 1.85019  R 12*300 20.43 0.05 23.2 AZT-22
2021-06-22 17:15:29 2.74206  r 75*60  21.82 0.26 22.6 AZT-20
2021-06-22 18:35:45 2.79606  R 12*300 21.21 0.09 23.1 AZT-22
2021-06-26 20:15:18 6.86520  R 20*180 22.55 0.24 23.2 AZT-22
2021-07-02 20:16:53 12.86630 R 12*300 23.5  0.3  23.5 AZT-22
2021-07-08 19:16:40 18.83003 r 76*60  n/d   n/d  23.2 AZT-20
2021-07-18 19:50:46 28.84816 R 12*300 n/d   n/d  23.9 AZT-22

Photometry is based on the USNO-B1.0 and PanSTARRS-PS1 nearby stars.
USNO-B1.0_id R2 I
1238-0493928 15.08 14.33
1238-0494511 15.67 15.03
1238-0493842 17.53 17.36
1238-0493787 16.81 16.12

PanSTARRS-PS1
RA DEC r
21:18:52.24182 +33:49:14.6348 15.2925
21:18:45.71408 +33:50:40.3319 18.1642

Using our data and those published in the GCN circulars cited above we 
plot a light curve which an be found at

http://grb.rssi.ru/GRB210619B/GRB210619B_LC_all.png

Using only Maidanak data after 0.7 days, it was found that the light 
curve can be fitted by a single power law with the index alpha = -1.48 
+/-0.04. Using early data published in GCNs we can describe the LC by a 
broken power law with parameters of alpha = -0.72+/-0.01, beta = -1.52 
+/-0.04, and break time of 0.57+/-0.12.

The fitted LC can be found at

http://grb.rssi.ru/GRB210619B/GRB210619B_AZT22_LC.png

It confirms the steeping decay suggested by Jelinek et al., GCN 30281, 
Kumar et al., GCN 30286. The power-law index before the break is 
approximately the same as that obtained by Kann et al., GCN 30338 and 
Oganesyan et al., arXiv:2109.00010, while the power law index after the 
break is steeper and coincides with XRT afterglow power law index.

We also not detected any influence of host galaxy on afterglow light 
curve, and after late time observations we can estimate brightness of 
the host galaxy R > 23.9.


GRB_name: GRB210909B
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30798
SUBJECT: GRB 210909B: GECAM detection
DATE:    21/09/10 15:02:21 GMT
FROM:    Shuo Xiao at IHEP  <xiaoshuo@ihep.ac.cn>

S. Xiao, S. L. Xiong, Y. Zhao, X. Y. Zhao, Y. Huang, X. Y. Song, C. Cai,
S. L. Xie, Y. Q. Zhang, Z. W. Guo, J. C. Liu, C. Zheng, W. C. Xue, C. Y. Li,
C. W. Wang, Q. B. Yi, B. X. Zhang, P. Zhang, W. X. Peng, R. Qiao, D. Y. Guo,
X. B. Li, X. Ma, P. Wang, J. Wang, Z. Zhang, S. J. Zheng, W. Chen, J. J. He, 
G. Y. Zhao, Y. Q. Du, H. Wu, J. Liang, Q. Luo, X. L. Zhang,
L. M. Song, F. J. Lu, S. N. Zhang (IHEP), report on behalf of GECAM team:

During the commissioning phase, GECAM-B was triggered in-flight by a long
burst, GRB 210909B, at 2021-09-09T20:02:33.600 UTC (denoted as T0), 
which was also detected by INTEGRAL/SPI-ACS.

According to the GECAM-B light curves in about 15-3500 keV, 
this burst mainly consists of a broad pulse with a duration of about 10 s.

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/utn210909_200233_GECAMb.png

GECAM-B localized this burst to the following position (J2000):
Ra: 358.6 deg
Dec: -74.9 deg
Err: 1.1 deg (1-sigma, statistical only)
The systematic error of location is estimated to be several degrees. 

Please note that all GECAM results here are preliminary. The final analysis
will be published in journal papers or GECAM online catalog.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor
(GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in
Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time),
which was funded by the Chinese Academy of Sciences (CAS).


GRB_name: GRB210826A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30799
SUBJECT: GRB 210826A: further Swift-XRT observations
DATE:    21/09/10 15:32:21 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <pda.davanzo@gmail.com>

P. D'Avanzo, M. G. Bernardini, A. Melandri, T. Sbarrato (INAF-OAB), P. A. Evans (U. Leicester) report on behalf of the Swift team:

Swift-XRT has performed further follow-up observations of GRB 210826A (Ohno et al. GCN Circ. 30721), collecting a total of 14.6 ks 
of Photon Counting (PC) mode data between T0+36.5 ks ks and T0+1.26e6 s. 

Of the 8 X-ray uncatalogued sources detected in the first observing epoch (D'Ai et al., GCN Circ. 30725), Source 1 and Source 5 are 
still detected with a consistent count-rate. The other sources are not detected down to a typical 3sigma upper limit of ~ 3e-3 ct/s. 
Therefore, we found no clear evidence for an X-ray afterglow candidate of GRB 210826A. 

The results of the XRT-team automatic analysis of the XRT observations, including a position-specific upper limit calculator, 
are available at https://www.swift.ac.uk/xrt_products/TILED_GRB00101.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB210912A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30820
SUBJECT: GRB 210912A: Swift detection of a burst
DATE:    21/09/12 11:18:18 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

E. Troja (NASA/GSFC/UMCP), A. P. Beardmore (U Leicester),
R. Caputo (NASA/GSFC), N. J. Klingler (GSFC/UMBC/CRESSTII),
F. E. Marshall (NASA/GSFC), K. L. Page (U Leicester) and
D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 11:01:11 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210912A (trigger=1072990).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 129.769, +79.194 which is 
   RA(J2000) = 08h 39m 04s
   Dec(J2000) = +79d 11' 38"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a complex
structure with a duration of about 40 sec.  The peak count rate
was ~2800 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 11:02:04.1 UT, 52.6 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
fading, uncatalogued X-ray source located at RA, Dec 129.88358,
79.22292 which is equivalent to:
   RA(J2000)  = 08h 39m 32.06s
   Dec(J2000) = +79d 13' 22.5"
with an uncertainty of 7.5 arcseconds (radius, 90% containment). This
location is 129 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
https://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 2.40
x 10^20 cm^-2 (Willingale et al. 2013). 

The initial flux in the 2.5 s image was 6.40e-10 erg cm^-2 s^-1 (0.2-10
keV). 

There are no UVOT data available. 

Burst Advocate for this burst is E. Troja (eleonora.troja AT nasa.gov). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)


GRB_name: GRB210912B
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30821
SUBJECT: GRB 210912B: Fermi GBM Final Real-time Localization
DATE:    21/09/12 12:38:51 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 12:31:34 UT on 12 Sep 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210912B (trigger 653142699.29167 / 210912522).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 344.9, Dec = 24.6 (J2000 degrees, equivalent to J2000 22h 59m, 24d 36'), with a statistical uncertainty of 12.3 degrees.

The angle from the Fermi LAT boresight is 103.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210912522/quicklook/glg_skymap_all_bn210912522.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210912522/quicklook/glg_healpix_all_bn210912522.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210912522/quicklook/glg_lc_medres34_bn210912522.gif


GRB_name: GRB210912A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30823
SUBJECT: GRB 210912A: BOOTES-5/JGT optical afterglow candidate
DATE:    21/09/12 15:04:10 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

Y.-D. Hu, T.-R. Sun, E. Fernandez-Garcia, A. J. Castro-Tirado, R. Sanchez-Ramirez and M.D. Caballero-Garcia (IAA-CSIC), D. Hiriart and W. H. Lee (UNAM), C. J. Perez del Pulgar and I. Carrasco (UMA), I. H. Park (SKKU) on behalf of a larger collaboration, report:

The 60cm BOOTES-5/JGT robotic telescope at Observatorio Astronomico Nacional in San Pedro Martir (Mexico) automatically responded in 13 s to the Swift trigger for GRB 210912A (Troja et al., GCNC 30820). In the co-added clear image (30 x 1 s), we find an uncataloged optical source at (J2000) coordinates RA: 8:39:34.30, DEC:+79:13:17.5,  which is located at the edge of the XRT error box (Troja et al., GCNC 30820) and for which we measure R = 18.5 mag. We propose this source to be the GRB 210219A optical afterglow, pending confirmation of its variability. Further observations are ongoing.

We thak the staff at San Pedro Martir for their support.


GRB_name: GRB210912A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30824
SUBJECT: Swift GRB 210912A: Global MASTER-Net observations report 
DATE:    21/09/12 16:40:30 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev, O.Ershova 
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

V. Yurkov, A. Gabovich, Yu. Sergienko 
(Blagoveschensk Educational State University)




MASTER-Kislovodsk robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB 210912A ( E. Troja et al., GCN 30820) errorbox  19826 sec after notice time and 19878 sec after trigger time at 2021-09-12 16:32:29 UT, with upper limit up to  15.0 mag. Observations started at twilight.  The observations began at zenith distance = 57 deg. The sun  altitude  is -12.6 deg. 

The galactic latitude b = 32 deg., longitude l = 134 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1718486

We obtain a following upper limits.  

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

    5800 |             MASTER- |   C |    25 | 13.0 |        
    8423 |             MASTER- |   C |    20 | 17.6 |        
    8423 |             MASTER- |   C |    20 | 13.9 |        
   19968 |   MASTER-Kislovodsk |   C |   180 | 15.0 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB210912A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30825
SUBJECT: GRB 210912A: Mondy optical afterglow confirmation
DATE:    21/09/12 17:21:48 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

N. Pankov (HSE), S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP) 
report  on behalf of GRB IKI FuN:

We observed the field of GRB 210912A (Troja et al., GCN 30820) with 
AZT-33IK telescope of Sayan observatory (Mondy)  starting on 
2021-09-12(UT) 12:57:48.  We obtained 30 images in R-filter. We confirm 
the fading object suggested by Hu et al. (GCN 30823) as the optic 
afterglow of GRB 210912A.   Preliminary photometry of the object in 
stacked images is following

Date       UT start   t-T0       Filter Exp.   OT    Err.  UL(3sigma)
                     (mid, days)        (s)

2021-09-12 12:57:48  0.10112    R     29*120   21.33 0.14  22.5

The photometry is based on the nearby USNO-B1.0 stars
RA DEC R2
08:39:12.26208 +79:12:37.1304 15.88
08:39:10.94880 +79:16:33.8916 15.26


GRB_name: GRB210912A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30829
SUBJECT: GRB 210912A: Host-galaxy candidate in PanSTARRS
DATE:    21/09/12 18:48:08 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

D. A. Kann (HETH/IAA-CSIC) reports:

At the afterglow position (Hu et al., GCN #30823, see also Pankov et 
al., GCN #30825) of the Swift GRB 210912A (Troja et al., GCN #30820), an 
object is visible in Pan-STARRS pre-imaging at position (J2000):

RA = 129.89171813
Dec. = +79.22157927

in agreement with the position given by Hu et al., GCN #30823,

with magnitudes:

g' = 23.19 +/- 0.23 mag,
r' = 23.09 +/- 0.36 mag,
i' = 22.48 +/- 0.13 mag,
z' = 22.43 +/- 0.25 mag.

It is undetected in Y.

We suggest this object to be the host galaxy of GRB 210912A. This may be 
indicative that this is a low-redshift event which may be followed by a 
detectable supernova.

Further follow-up despite the very northerly position is warranted.


GRB_name: GRB210912A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30830
SUBJECT: GRB 210912A: Enhanced Swift-XRT position
DATE:    21/09/12 20:48:34 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 526 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 210912A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 129.88990, +79.22148 which is equivalent
to:

RA (J2000): 08h 39m 33.58s
Dec (J2000): +79d 13' 17.3"

with an uncertainty of 2.6 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB210912A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30832
SUBJECT: GRB 210912A: Swift/UVOT Detection
DATE:    21/09/13 07:47:54 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and E. Troja (NASA/GSFC/UMCP)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210912A
60 s after the BAT trigger (Troja et al., GCN Circ. 30820).
A source consistent with the optical position
(Hu et al. GCN Circ. 30823)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  08:39:34.27 = 129.89280 (deg.)
    Dec (J2000) = +79:13:17.1  =  79.22141 (deg.)
with an estimated uncertainty of 0.47 arc sec. (radius, 90% confidence).

Preliminary detections and 3-sigma upper limits using the UVOT photometric
system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures
are:

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white               60          209          147         18.73 +/- 0.08
v                  602          621           19        >17.8
b                  528          547           19        >18.3
u                  272          490          214         19.56 +/- 0.31
w2                 577          597           19        >18.8

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.027 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB210912A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30833
SUBJECT: GRB 210912A: Swift-XRT refined Analysis
DATE:    21/09/13 09:18:53 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A.P. Beardmore (U. Leicester), M. Capalbi (INAF-IASFPA), M. Perri (SSDC
& INAF-OAR), V. D'Elia (SSDC & INAF-OAR), D.N. Burrows (PSU), J. D.
Gropp (PSU), J.A. Kennea (PSU), P.A. Evans (U. Leicester), J.P. Osborne
(U. Leicester) and E. Troja report on behalf of the Swift-XRT team:

We have analysed 4.1 ks of XRT data for GRB 210912A (Troja et al. GCN
Circ. 30820), from 46 s to 29.0 ks after the  BAT trigger. The data
comprise 32 s in Windowed Timing (WT) mode (the first 5 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The enhanced XRT position for this burst was given by Evans et
al. (GCN Circ. 30830).

The light curve can be modelled with an initial power-law decay with an
index of alpha=3.4 (+/-0.4), followed by a break at T+140 s to an alpha
of 0.68 (+/-0.05).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.67 (+0.25, -0.23). The
best-fitting absorption column is  1.2 (+0.9, -0.7) x 10^21 cm^-2, in
excess of the Galactic value of 2.4 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 4.1 x 10^-11 (4.7 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.2 (+0.9, -0.7) x 10^21 cm^-2
Galactic foreground: 2.4 x 10^20 cm^-2
Excess significance: 2.2 sigma
Photon index:      1.67 (+0.25, -0.23)

If the light curve continues to decay with a power-law decay index of
0.68, the count rate at T+24 hours will be 0.014 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.7 x
10^-13 (6.6 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01072990.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB210912A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30834
SUBJECT: GRB 210912A: CAHA 2.2m Detection
DATE:    21/09/13 09:35:41 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/IAA-CSIC, 
DARK/NBI), C. Thoene, M. Blazek, J. F. Agui Fernandez (all 
HETH/IAA-CSIC), and S. Gongora (CAHA) report:

We observed GRB 210912A (Swift detection: Troja et al., GCN #30820) with 
CAFOS mounted on the 2.2m CAHA telescope at Calar Alto, Almeria, Spain. 
We obtained 7 x 60 s in the SDSS i' band under passing clouds, starting 
at 20:04:34 UT (9.056 hrs after the trigger; further observations at a 
later time were prevented by cloud cover). The afterglow (Hu et al., GCN 
#30823; Pankov et al., GCN #30825; Kuin & Troja, GCN #30832) is faintly 
detected in the stacked image.

Compared to a nearby Pan-STARRS comparison star, we measure (AB mag) i' 
= 21.66 +/- 0.15 mag at 0.38146 d after the GRB, further confirming the 
decaying afterglow. This is still significantly brighter than the 
potential underlying host galaxy (Kann, GCN #30829).


GRB_name: GRB210912A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30837
SUBJECT: GRB 210912A: Tautenburg observations
DATE:    21/09/13 16:25:04 GMT
FROM:    Ana Nicuesa at TLS Tautenburg  <ana@tls-tautenburg.de>

A. Nicuesa Guelbenzu, S. Klose, S. Melnikov, B. Stecklum, C. Hoegner (all
TLS Tautenburg) report:

We observed the field of GRB 210912A (Troja et al., GCN 30820) with the
Tautenburg 1.34m Schmidt telescope equipped with the TAUKAM 6kx6k CCD
camera and the Sloan r-band filter.

Observations were performed on September 12, at a midtime of 19.33 UT,
22.17 UT, and 02:36 UT (Sep 13). The optical transient (Hu et al., GCN
30823; Pankov et al., GCN 30825; Kuin & Troja, GCN 30832; Kann et al. GCN
30833) is detected with the following preliminary AB magnitudes:

r_1 = 21.95 +- 0.19,
r_2 = 22.17 +- 0.19,
r_3 = 22.53 +- 0.19.

Magnitudes are calibrated against the Pan-STARRS catalogue.

A comparison with the previous observations suggests that around 0.6 days
the decay index of the light curve has increased from a rather modest
value of alpha = 0.4 to alpha about 1. Further observations are required
in order to provide a more precise decay index.


GRB_name: GRB210912A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30839
SUBJECT: GRB 210912A: Swift-BAT refined analysis
DATE:    21/09/13 23:34:08 GMT
FROM:    Sibasish Laha at GSFC  <sibasish.laha@nasa.gov>

M. Stamatikos (OSU), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Sakamoto (AGU),
(i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 210912A (trigger #1072990)
(Troja et al., GCN Circ. 30820).  The BAT ground-calculated position is
RA, Dec = 129.874, 79.216 deg which is
   RA(J2000)  =  08h 39m 29.7s
   Dec(J2000) = +79d 12' 59.3"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.

The BAT light curve showed a complex structure with a duration of about ~30 sec.
T90 (15-350 keV) is 28.35 +- 14.34 sec (estimated error including systematics).

The time-averaged spectrum from T-23 to T+25 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.61 +- 0.13.  The fluence in the 15-150 keV band is 1.1 +- 0.1 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+0.23 sec in the 15-150 keV band
is 1.7 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1072990/BA/


GRB_name: GRB210909A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30840
SUBJECT: GRB 210909A: Detection by GRBAlpha
DATE:    21/09/15 10:35:12 GMT
FROM:    Masanori Ohno at Hiroshima U  <ohno@astro.hiroshima-u.ac.jp>

J. Ripa (Masaryk U.), M. Ohno (Eotvos U./Konkoly Observatory/Hiroshima U.),
 H. Takahashi (Hiroshima U.), A. Pal, L. Meszaros, B. Csak (Konkoly
Observatory), N. Werner, M. Topinka, F. Munz, F. Hroch (Masaryk U.), T.
Urbanec, M. Kasal,  A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus,
M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M.
Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner
Research Center/Eotvos U.), Yuusuke Uchida, Helen Poon, H. Matake, N.
Uchida (Hiroshima U.), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), T.
Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa,
K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.),
K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno
(Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J.
Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.) -- the GRBAlpha
collaboration.

The short duration GRB 210909A (Fermi-GBM detection; GCN Circ.  30786) was
detected by the GRBAlpha 1U CubeSat (Pal et al. Proc. SPIE 2020).

The light curve shows a short spike structure within the 4 s time bin. The
detection had significance of the SNR = 8.8.

The light curve obtained by GRBAlpha is available here:
https://grbalpha.konkoly.hu/static/share/GRB210909A_GCN.pdf

GRBAlpha is a demonstration mission for a future CubeSats constellation
(Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75
x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy
range from ~50 keV to ~1000 keV. GRBAlpha was launched on 2021 March 22
from Baikonur. After its commissioning phase, the scientific observations
are now under way. To increase the duty cycle and the downlink rate, the
upgrade of the on-board data acquisition software stack is in progress. The
ground segment is also supported by the radio amateur community and it
takes advantage of the SatNOGS network for increased data downlink volume.


GRB_name: GRB210812A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30842
SUBJECT: GRB 210812A is not a compelling example of a lensed GRB
DATE:    21/09/15 23:50:45 GMT
FROM:    Robert Nemiroff at Michigan Tech.  <nemiroff@mtu.edu>

Oindabi Mukherjee (Michigan Tech U.) & Robert J. Nemiroff (Michigan Tech
U.) report:

A preliminary light curve and hardness comparison between the two main
pulses of GRB 210812A has been done using Fermi GBM data to test for
gravitational lensing (as suggested by Veres et al. 2021, GCN 30645).

First, an amplitude-equalized light curve comparison of combined energy
bands 3  through 7 in detectors 2, 7, 8, 9, 10, 11, and 12 shows a chi^2
difference of 2.796 sigma, so that there is only a 0.52% chance of the two
pulses being randomly drawn from the same pulse.

Additionally, a hardness analysis shows that in energy channels 4 and 5,
the hardness difference between the two pulses differs at the 2.24 sigma
level, with the second pulse being softer.

These preliminary results suggest that although the case of GRB 210812A is
interesting, it  is not a compelling example of a GRB gravitational lens.

A more thorough analysis is ongoing.


GRB_name: GRB210917A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30843
SUBJECT: GRB 210917A: Fermi GBM Final Real-time Localization
DATE:    21/09/17 03:56:05 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 03:45:47 UT on 17 Sep 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210917A (trigger 653543152.223672 / 210917157).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 75.5, Dec = -36.2 (J2000 degrees, equivalent to J2000 05h 01m, -36d 12'), with a statistical uncertainty of 5.6 degrees.

The angle from the Fermi LAT boresight is 90.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210917157/quicklook/glg_skymap_all_bn210917157.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210917157/quicklook/glg_healpix_all_bn210917157.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210917157/quicklook/glg_lc_medres34_bn210917157.gif


GRB_name: GRB210912A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30844
SUBJECT: GRB 210912A: BOOTES-5/JGT optical afterglow candidate (Correction to GCNC 30823)
DATE:    21/09/17 11:55:37 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

Y.-D. Hu, T.-R. Sun, E. Fernandez-Garcia, A. J. Castro-Tirado, R. Sanchez-Ramirez and M.D. Caballero-Garcia (IAA-CSIC), D. Hiriart and W. H. Lee (UNAM), C. J. Perez del Pulgar and I. Carrasco (UMA), I. H. Park (SKKU) on behalf of a larger collaboration, report:

The 60cm BOOTES-5/JGT robotic telescope at Observatorio Astronomico Nacional in San Pedro Martir (Mexico) automatically responded in 13 s to the Swift trigger for GRB 210912A (Troja et al., GCNC 30820). In the co-added clear image (30 x 1 s), we find an uncataloged optical source at (J2000) coordinates RA: 8:39:34.30, DEC:+79:13:17.5,  which is located at the edge of the XRT error box (Troja et al., GCNC 30820) and for which we measure R = 18.5 mag. We propose this source to be the GRB 210912A optical afterglow, pending confirmation of its variability. Further observations are ongoing.

We thank the staff at San Pedro Martir for their support.

In the GCNC 30823, we have a typo of the GRB name in the text and it was corrected now. We apologize for the possible confusion and inconvenience.


GRB_name: GRB210919A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30846
SUBJECT: GRB 210919A: Swift detection of a short burst
DATE:    21/09/19 00:54:18 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

A. Tohuvavohu (U Toronto), S. D. Barthelmy (GSFC),
A. Y. Lien (U Tampa) and B. Sbarufatti (PSU) report on behalf of the
Neil Gehrels Swift Observatory Team:

At 00:28:33 UT, the Swift Burst Alert Telescope (BAT) triggered and
located a short GRB 210919A (trigger=1073893). Swift slewed immediately 
to the burst. The BAT on-board calculated location is 
RA, Dec 80.230, +1.274 which is 
   RA(J2000) = 05h 20m 55s
   Dec(J2000) = +01d 16' 27"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 0.3 sec.  The peak count rate
was ~3500 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 00:30:10.5 UT, 97.0 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 80.25441, 1.31189 which is equivalent
to:
   RA(J2000)  = 05h 21m 01.06s
   Dec(J2000) = +01d 18' 42.8"
with an uncertainty of 6.9 arcseconds (radius, 90% containment). This
location is 162 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
https://www.swift.ac.uk/sper.  We cannot determine whether the source
is fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 1.56
x 10^21 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 99 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers none of
the XRT error circle. The 8'x8' region for the list of sources generated
on-board covers 100% of the XRT error circle. The list of sources is typically
complete to about 18 mag. No correction has been made for the expected
extinction corresponding to E(B-V) of 0.142. 

Burst Advocate for this burst is A. Tohuvavohu (tohuvavohu AT astro.utoronto.ca). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)


GRB_name: GRB210919A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30847
SUBJECT: Swift GRB 210919A: Global MASTER-Net observations report 
DATE:    21/09/19 01:48:24 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev, O.Ershova 
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

V. Yurkov, A. Gabovich, Yu. Sergienko 
(Blagoveschensk Educational State University)




MASTER-SAAO robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in South Africa (South African Astronomical Observatory) was pointed to the Swift GRB 210919A ( A. Tohuvavohu et al., GCN 30846) errorbox 47 sec after trigger time at 2021-09-19 00:29:20 UT, with upper limit up to  18.6 mag. The observations began at zenith distance = 61 deg. The sun  altitude  is -49.0 deg. 

MASTER-Kislovodsk robotic telescope  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB 210919A errorbox  363 sec after notice time and 790 sec after trigger time at 2021-09-19 00:41:44 UT, with upper limit up to  14.3 mag. The observations began at zenith distance = 50 deg. The sun  altitude  is -24.1 deg. 

The galactic latitude b = -19 deg., longitude l = 201 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1725958

We obtain a following upper limits.  

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

      52 |         MASTER-SAAO | P\  |    10 | 16.1 |        
      67 |         MASTER-SAAO | P\  |    40 | 17.0 |  Coadd 
     397 |         MASTER-SAAO | P\  |   700 | 18.4 |  Coadd 
      77 |         MASTER-SAAO | P\  |    10 | 16.4 |        
     103 |         MASTER-SAAO | P\  |    20 | 16.6 |        
     141 |         MASTER-SAAO | P\  |    30 | 16.0 |        
     176 |         MASTER-SAAO | P\  |   100 | 16.6 |  Coadd 
     183 |         MASTER-SAAO | P\  |    30 | 14.7 |        
     230 |         MASTER-SAAO | P\  |    40 | 16.4 |        
     288 |         MASTER-SAAO | P\  |    50 | 15.9 |        
     358 |         MASTER-SAAO | P\  |   190 | 16.6 |  Coadd 
     355 |         MASTER-SAAO | P\  |    60 | 15.1 |        
     437 |         MASTER-SAAO | P\  |    80 | 16.4 |        
     541 |         MASTER-SAAO | P\  |   100 | 17.8 |        
     676 |         MASTER-SAAO | P\  |   370 | 18.6 |  Coadd 
     662 |         MASTER-SAAO | P\  |   120 | 17.8 |        
     810 |         MASTER-SAAO | P\  |   150 | 18.1 |        
     871 |   MASTER-Kislovodsk |  P| |   160 | 14.2 |        
     987 |         MASTER-SAAO | P\  |   180 | 17.5 |        
    1167 |         MASTER-SAAO | P\  |   540 | 17.9 |  Coadd 
    1048 |   MASTER-Kislovodsk |  P- |   180 | 12.4 |        
    1048 |   MASTER-Kislovodsk |  P| |   180 | 14.1 |        
    1188 |         MASTER-SAAO | P\  |   180 | 17.4 |        
    1249 |   MASTER-Kislovodsk |  P- |   180 | 12.9 |        
    1249 |   MASTER-Kislovodsk |  P| |   180 | 14.2 |        
    1387 |         MASTER-SAAO | P\  |   180 | 17.4 |        
    1449 |   MASTER-Kislovodsk |  P- |   180 | 13.4 |        
    1449 |   MASTER-Kislovodsk |  P| |   180 | 14.3 |        
    1587 |         MASTER-SAAO | P\  |   180 | 17.4 |        
    1650 |   MASTER-Kislovodsk |  P- |   180 | 13.6 |        


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB210919A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30848
SUBJECT: GRB 210919A: BOOTES-2/TELMA optical upper limit
DATE:    21/09/19 01:57:54 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

Y.-D. Hu, T.-R. Sun, E. Fernandez-Garcia, A. J. Castro-Tirado, M.D. Caballero-Garcia (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), R. Fernandez-Munoz (IHSM/UMA-CSIC) and M. Jelinek (ASU-CAS), on behalf of a larger collaboration, report:

The 60cm BOOTES-2/TELMA robotic telescope at IHSM La Mayora (UMA-CSIC) in Algarrobo Costa (Malaga, Spain) automatically responded to the Swift trigger of short GRB 210919A (Tohuvavohu et al. GCNC 30846). Images were taken starting at 00:32 UT on 19 Sep (~4 min after trigger) under high airmass conditions. In the co-added 10 x 10 s exposure image (clear filter), no optical afterglow is detected within the reported XRT/Swift source position (Tohuvavohu et al. GCNC 30846) down to 17.5 mag. This non-detection is consistent with reports from Tohuvavohu et al.(GCNC 30846) and Lipunov et al.(GCNC 30847).

We thank the staff at La Mayora for its excellent support.


GRB_name: GRB210919A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30849
SUBJECT: GRB 210919A: LCO Optical Upper Limit
DATE:    21/09/19 04:55:40 GMT
FROM:    Robert Strausbaugh at U. of the Virgin Islands  <robert.strausbaugh@uvi.edu>

R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (U. of the Virgin Islands/College of Marin) report on behalf of a larger collaboration:

We observed Swift GRB 210919A (Tohuvavohu, et al., GCN 30846) with the LCO 1-m Sinistro instrument at the South African Astronomical Observatory site, on September 19, from 01:41 to 02:08 UT (corresponding to 1.22 to 1.67 hours from the GRB trigger time) with the Bessel R and I filters.

We performed a series of 4x200s exposures in R and 3x200s in I. In the large XRT detection region (Tohuvavohu, et al., GCN 30846) we find no obvious optical counterpart could be detected down to the following upper limits (consistent with previous reports (Tohuvavohu et al., GCNC 30846; Lipunov et al., GCNC 30847; Hu et al., GCN 30848)), calculated using the USNO-B.1 catalog as reference:

R>20.5
I>18.7

These magnitudes are not corrected for galactic extinction.

R.S. is funded by NSF AST grant #1831682


GRB_name: GRB210919A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30850
SUBJECT: GRB 210919A: Enhanced Swift-XRT position
DATE:    21/09/19 05:06:55 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

M.R. Goad, J.P. Osborne, A.P. Beardmore and P.A. Evans (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 453 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 210919A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 80.25448, +1.31153 which is equivalent
to:

RA (J2000): 05h 21m 1.08s
Dec (J2000): +01d 18' 41.5"

with an uncertainty of 4.6 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB210919A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30851
SUBJECT: GRB 210919A: AbAO optical upper limit
DATE:    21/09/19 09:24:53 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

N. Pankov (HSE, IKI),  R. Ya. Inasaridze (AbAO), A. Pozanenko (IKI), S. 
Belkin (IKI), D. Datashvili (AbAO), V. R. Ayvazian (AbAO),  G. V. 
Kapanadze (AbAO)  report on behalf of GRB IKI FuN:

We observed  the field of Swift short GRB 210919A (Tohuvavohu et al. GCN 
30846)  with AS-32 telescope of Abastumani observatory (AbAO) in 
R-filter starting on Sep., 19 (UT) 00:48:33. We do not detect any object 
in the enhanced XRT position (Goad et al. GCN 30850). This is consistent 
with optical observations (Tohuvavohu et al. GCN 30846; Lipunov et al., 
GCN 30847; Hu et al. GCN 30848; Strausbaugh et al. GCN 30849).

Preliminary photometry of the field  is following

Date       UT start   t-T0    Filter Exp.    OT   Err.  UL(3sigma)
                        (mid, days)    (s)

2021-09-19 00:48:33   0.03194  R     52*60   n/d  n/d   22.1

The photometry is based on the nearby SDSS stars:
SDSS-DR12 R(Lupton)
5:21:01.5917 +1:18:14.862 17.82
5:20:58.8314 +1:18:59.733 18.36


GRB_name: GRB210919A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30852
SUBJECT: GRB 210919A: NOT upper limits
DATE:    21/09/19 12:24:18 GMT
FROM:    Daniel Perley at Liverpool JMU  <d.a.perley@ljmu.ac.uk>

D. A. Perley (LJMU), Z. P. Zhu (NAOC, HUST), D. Xu, S.Y. Fu (NAOC), D. 
B. Malesani (DTU Space), and A. Avramova-Boncheva (NOT) report:

We observed the field of GRB210919A (Tohuvavohu et al. GCN 30846) using 
the Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. We 
obtained 3x300s frames in the Sloan r-band filter and 5x240s in the 
i-band filter.  Observations were carried out on 2021-09-19 between 
03:29 and 04:08 UT.

No source is detected inside the enhanced XRT error circle (Goad et al., 
GCN 30850), to 3-sigma limits of: r>23.4 mag (at t=3.15 hours 
post-trigger) and i>23.9 (at t=3.47 hours post-trigger).






DisclaimerNone


GRB_name: GRB210919B
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30853
SUBJECT: GRB 210919B: Fermi GBM Final Real-time Localization
DATE:    21/09/19 15:51:07 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely SHORT GRB

At 15:39:51 UT on 19 Sep 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210919B (trigger 653758796.95736 / 210919653).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 215.2, Dec = -77.1 (J2000 degrees, equivalent to J2000 14h 20m, -77d 05'), with a statistical uncertainty of 9.2 degrees.

The angle from the Fermi LAT boresight is 53.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210919653/quicklook/glg_skymap_all_bn210919653.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210919653/quicklook/glg_healpix_all_bn210919653.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210919653/quicklook/glg_lc_medres34_bn210919653.gif


GRB_name: GRB210919A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30854
SUBJECT: GRB 210919A: Swift-XRT refined Analysis
DATE:    21/09/19 15:57:30 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), A. D'Ai
(INAF-IASFPA), J. D. Gropp (PSU), J.A. Kennea (PSU), P.A. Evans (U.
Leicester), J.P. Osborne (U. Leicester), K.L. Page (U. Leicester) and
A. Tohuvavohu report on behalf of the Swift-XRT team:

We have analysed 1.5 ks of XRT data for GRB 210919A (Tohuvavohu et al.
GCN Circ. 30846), from 105 s to 1.6 ks after the  BAT trigger. The data
are entirely in Photon Counting (PC) mode. The enhanced XRT position
for this burst was given by Goad et al. (GCN Circ. 30850). We cannot
determine at the present time whether the source is fading.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01073893.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB210919A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30855
SUBJECT: GRB 210919A: MITSuME Akeno optical upper limits
DATE:    21/09/20 00:36:51 GMT
FROM:    Yutaka Takamatsu at Tokyotech  <takamatsu@hp.phys.titech.ac.jp>

Y. Takamatsu, R. Hosokawa, K. L. Murata, N. Ito, Y. Imai, M. Niwano,
R. Noto, S. Sato, M. Takaku, R. Yamaguchi, Y. Yatsu, and N. Kawai
(TokyoTech) report on behalf of the MITSuME collaboration:

We observed the field of GRB 210919A (A. Tohuvavohu et al. GCN
Circular #30846, V. Lipunov et al. GCN Circular #30847, Y.-D. Hu et
al. GCN Circular #30848, R. Strausbaugh et al. GCN Circular #30849,
M.R. Goad et al. GCN Circular #30850, N. Pankov et al. GCN Circular
#30851, D. A. Perley et al. GCN Circular #30852, M. Perri et al. GCN
Circular #30854) with the optical three color (g', Rc, and Ic) CCD
cameras attached to the MITSuME 50 cm telescope Akeno. The observation
with a series of 60 sec exposures started at 2021-09-19 15:22:32 UT
(14.9 hours after Swift trigger). We stacked the images with good
conditions. We did not detect any uncatalogued sources within the XRT
error region (M.R. Goad et al. GCN Circular #30850). We obtained the
5-sigma limits of the stacked images as follows.

T0+[hour] MID-UT T-EXP[sec] 5-sigma limits
------------------------------------------------------------------------------------------------
17.3 2021-09-19 17:48:08.43 11160 g'>19.2, Rc>20.5, Ic>19.6
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time

We used PS1 catalog for flux calibration.
The magnitudes are expressed in the AB system.
The images were processed in real-time through the MITSuME GPU
reduction pipeline (Niwano et al. 2021, PASJ, Vol.73, Issue 1, Pages
4-24; https://github.com/MNiwano/Eclaire).


GRB_name: GRB210919A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30856
SUBJECT: GRB 210919A: LOAO and LSGT optical upper limits
DATE:    21/09/20 08:00:38 GMT
FROM:    Sophia Kim at Seoul National U.  <sophiak@astro.snu.ac.kr>

GRB 210919A: LOAO and LSGT optical upper limits


Sophia Kim (Seoul National University, SNU), Myungshin Im (SNU); Jeff Cooke
(Swinburne University of Technology), Gu Lim (SNU); report on behalf of
IMSNG & GECKO Collaboration


We carried out follow-up observations of GRB210919A (A. Tohuvanohu et al.
GCNC #30846) with the 1-m telescope at Mt. Lemon Optical Astronomy
Observatory (LOAO) in US Arizona. Observations began on September 19 at
10:42:02 UT , ~10.23 hours after the GRB trigger. We took 19 X 180s
exposures in Johnson R-band.

We also observed the same field with the 0.43-meter (17 inch) Lee Sang Gak
Telescope (LSGT) located at the Siding Spring Observatory (SSO) in
Australia. Imaging began on the same day at 16:12:53 UT, ~15.73 hours after
the GRB trigger. The observations were performed in a Sloan r-, i- and
z-band sequences with 11 X  300s exposures in each band.


No GRB optical counterpart was found in the LOAO and LSGT data within the
XRT error area (M. R. Goad et al. GCNC #30850). This result is consistent
with the optical observational results by other teams (V. Lipunov et al.
GCNC #30847, Y.-D. Hu et al. GCNC #30848, R. Strausbaugh et al. GCNC
#30849, M.R. Goad et al. GCNC #30850, N. Pankov et al. GCNC #30851, D. A.
Perley et al. GCNC #30852, M. Perri et al. GCNC #30854 and Y.Takamatsu et
al. GCNC #30855).


The following is our observation results.

We calibrated flux with the PS1 catalog and used AB magnitude system. (The
magnitudes are not corrected for extinction.)


#--------------------------------------------------------------------------------------------------------------

OBS/TEL DATE-OBS(UT) FILTER EXPT UL(3Ïƒ)[ABmag] UL(5Ïƒ)[ABmag]

LOAO/1-m 2021-09-19T10:42:02 R 3420s >21.716  >21.162

SSO/LSGT 2021-09-19T16:12:53 r 3300s >20.160  >19.605

SSO/LSGT 2021-09-19T16:18:17 i 3300s >19.107  >18.553

SSO/LSGT 2021-09-19T16:23:53 z 3300s >18.674  >18.119

--------------------------------------------------------------------

[GCN OPS NOTE(20sep2021):  Per author's request, the signiture block
that is automatically added to the bottom has been removed.]


GRB_name: GRB210919A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30857
SUBJECT: GRB 210919A: Swift/UVOT Upper Limits
DATE:    21/09/21 02:35:14 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <mhs18@psu.edu>

M. H. Siegel (PSU) and A. Tohuvavohu (U. Toronto)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210919A
100 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 30846).
No optical afterglow consistent with the XRT position
(Goad et al. GCN Circ. 30850) is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           100          249          147         >20.8
u_FC               312          561          246         >19.9
white              100         1193          343         >21.4
v                  643         1244           70         >18.7
b                  568         1342           63         >19.3
u                  312         1318          304         >19.8
w1                 693         1293           58         >19.7
m2                1248         1268           19         >19.0
w2                 618         1044           39         >19.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.141 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB210919A
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30858
SUBJECT: GRB210919A: Keck NIRC2 Kp band upper limits
DATE:    21/09/21 06:58:23 GMT
FROM:    Jielai Zhang at Swinburne U. of Tech.  <jielaizhangscience@gmail.com>

GRB210919A: Keck NIRC2 Kp band upper limits

Jielai Zhang (Swinburne University of Technology, Swinburne), Jeff Cooke
(Swinburne), Gabriela Canalizo (University of California Riverside), Sara
Marlene Doan (George Mason University), Shobita Satyapal (George Mason
University), Thomas Bohn (University of California Riverside), Jeffrey
Mckaig (George Mason University)

We carried out follow-up observations of GRB210919A (A. Tohuvanohu et al.
GCNC #30846) with Keck II, using the NIRC2 instrument with the wide camera.
Observations began on September 19 at 13:48:32.649 UT , ~13.3 hours after
the GRB trigger. We took 6 X 107s exposures using the Kp filter. No GRB IR
counterpart was found in the NIRC2 data within the XRT error area (M. R.
Goad et al. GCNC #30850).

No GRB IR counterpart was found in the NIRC2 data within the XRT error area
(M. R. Goad et al. GCNC #30850) to an upper limit of Kp > 21.5 mag (AB,
with no Galactic extinction correction).


GRB_name: GRB210919A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30859
SUBJECT: GRB 210919a: Lowell Discovery Telescope upper limits
DATE:    21/09/21 15:25:55 GMT
FROM:    Amy Gottlieb at UMD  <Agottlieb7@gmail.com>

[GCN OPS REPORT(21 Sep 2021):  Per submittor's request, this Circular
was removed because it was serverly covered with formating directives.
It will be resubmitted when a cleaner version is made.]


GRB_name: GRB210919A
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30860
SUBJECT: GRB 210919A: Lowell Discovery Telescope upper limits (correction to GCN 30859)
DATE:    21/09/21 19:15:27 GMT
FROM:    Amy Gottlieb at UMD  <Agottlieb7@gmail.com>

This is the corrected version of GCN 30859 submitted as plain text
instead of html.

A.Gottlieb (UMD, NASA-GSFC), S.Dichiara (UMD, NASA-GSFC),  S.B. Cenko
(NASA-GSFC), E. Troja (UMD, NASA-GSFC), J.M. Durbak (UMD), A. Kutyrev
(UMD, NASA-GSFC), S. Veilleux (UMD), report on behalf of a larger
collaboration:

We observed the field of the short GRB 210919A (Tohuvavohu et al.,
GCN Circ. 30846) using the Large Monolithic Imager (LMI) on the 4.3m
Lowell Discovery Telescope (LDT) at Happy Jack, AZ. Observations
started on September 21, 11:27:43 UT (2.46 days after the Swift
trigger) taking 5 exposures of 200 s each with SDSS r filter.
Observations were taken at an airmass of about 1.27 and seeing of
about 1.5". We do not find any source inside the enhanced
XRT position (Goad et al., GCN Circ. 30850) down to a 3-sigma
limiting magnitude of r>23.6 AB mag.
Magnitudes are calibrated against the SDSS catalog and not
corrected for Galactic extinction.

We thank the staff of the Lowell Discovery Telescope for assistance
with these observations.


GRB_name: GRB210912A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30861
SUBJECT: GRB 210912A: LBT optical observations
DATE:    21/09/22 11:41:40 GMT
FROM:    Andrea Melandri at INAF-OAB  <andrea.melandri@inaf.it>

A. Rossi (INAF-OAS Bologna) report on behalf of the CIBO collaboration:

We observed the field of GRB 210912A (Troja et al., GCN 30820) in the r' band with the LBC imager mounted on LBT (Mt Graham, AZ, USA). We obtained 10min of imaging at the midtime 11:20 UT on 2021-09-17 (~5 days after the burst trigger).

We clearly detect the optical afterglow (Hu et al., GCN 30823; Pankov et al., GCN 30825; Kuin & Troja, GCN 30832; Kann et al. GCN 30834; Nicuesa Guelbenzu et al. GCN 30837) with the following preliminary AB magnitude:

r = 22.73 +- 0.05

calibrated against Pan-STARRS field stars. It is likely that this flux is significantly affected by host galaxy contamination (Kann et al. GCN 30829).

We acknowledge the excellent support from the LBTO and LBT-INAF staff, particularly A. Cardwell, J. Williams and D. Paris, in obtaining these observations.


GRB_name: GRB210919A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30863
SUBJECT: GRB 210919A: Swift-BAT refined analysis
DATE:    21/09/22 22:04:47 GMT
FROM:    Sibasish Laha at GSFC  <sibasish.laha@nasa.gov>

S. D. Barthelmy (GSFC), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), A. Y. Lien (U Tempa),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU),
 M. Stamatikos (OSU) (i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 210919A (trigger #1073893)
(Tohuvavohu et al., GCN Circ. 30846).  The BAT ground-calculated position is
RA, Dec = 80.242, 1.286 deg which is
   RA(J2000)  =  05h 20m 58.1s
   Dec(J2000) = +01d 17' 08.8"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 50%.

The BAT light curve showed a short pulse of a duration ~ 1 sec.
T90 (15-350 keV) is 0.16 +- 0.03 sec (estimated error including systematics).

The time-averaged spectrum from T+0.05 to T+0.24 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.58 +- 0.27.  The fluence in the 15-150 keV band is 8.8 +- 1.7 x 10^-08 erg/cm2.
The 1-sec peak photon flux measured from T-0.35 sec in the 15-150 keV band
is 1.5 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1073893/BA/


GRB_name: GRB210923A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30865
SUBJECT: GRB 210923A: Fermi GBM Final Real-time Localization
DATE:    21/09/23 11:57:13 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely SHORT GRB

At 11:49:36 UT on 23 Sep 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210923A (trigger 654090581.820056 / 210923493).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 90.0, Dec = -6.5 (J2000 degrees, equivalent to J2000 06h 00m, -6d 30'), with a statistical uncertainty of 10.9 degrees.

The angle from the Fermi LAT boresight is 47.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210923493/quicklook/glg_skymap_all_bn210923493.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210923493/quicklook/glg_healpix_all_bn210923493.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210923493/quicklook/glg_lc_medres34_bn210923493.gif


GRB_name: GRB210919A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30868
SUBJECT: GRB 210919A: DECam Upper Limits
DATE:    21/09/23 14:09:18 GMT
FROM:    Justin Pierel at STScI  <jpierel@stsci.edu>

J. Pierel (STScI), J. Cooke (Swinburne U.), A. Rest (STScI), R. Foley (UCSC), and R. Ridden-Harper (U. Canterbury) report:

We observed the field of GRB210919A (Tohuvavohu et al. GCN 30846) using the Dark Energy Camera (DECam) instrument on the 4m Victor M. Blanco Telescope at CTIO. We obtained 5x250s exposures in the i and z-band from 08:20-09:05 UTC on 2021-09-21.

No source is detected inside the enhanced Swfit-XRT uncertainty radius (Goad et al., GCN 30850), to 3-sigma limits of: i>24.1 mag and z>23.6 mag.


GRB_name: GRB210923A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30873
SUBJECT: Retraction of Fermi GBM GRB 210923A: the trigger is not a GRB
DATE:    21/09/23 22:03:59 GMT
FROM:    Joe Mangan at UCD  <joseph.mangan@ucdconnect.ie>

J.Mangan (UCD), S.Lesage (UAH) report on behalf of the Fermi Gamma-ray
Burst Monitor Team:

The Fermi Gamma-ray Burst Monitor (GBM) trigger 654090581/210923493 at
11:49:36.820 UT
on 23 September 2021, tentatively classified as a GRB (GCN 30865), is in
fact not due
to a GRB. This trigger is likely due to a terrestrial electron beam (TEB).


GRB_name: GRB210923B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30874
SUBJECT: GRB 210923B: GECAM detection
DATE:    21/09/24 06:05:39 GMT
FROM:    Xiaolu Zhang at IHEP  <xlzhang@ihep.ac.cn>

GRB 210923B: GECAM detection

X. L. Zhang, S. L. Xiong, X. Y. Zhao, Y. Huang, X. Y. Song, C. Cai,
S. Xiao, S. L. Xie, Y. Q. Zhang, Y. Zhao, Z. W. Guo, C. Zheng, 
W. C. Xue, C. Y. Li, C. W. Wang, Q. B. Yi, B. X. Zhang, P. Zhang,
W. X. Peng, R. Qiao, D. Y. Guo, X. B. Li, X. Ma, P. Wang, J. Wang, 
Z. Zhang, S. J. Zheng, W. Chen, J. J. He, G. Y. Zhao, Y. Q. Du,
H. Wu, J. Liang, Q. Luo, J. C. Liu, 
L. M. Song, F. J. Lu, S. N. Zhang (IHEP), report on behalf of GECAM team:

During the commissioning phase, GECAM-B was triggered ground by a short
bright burst, GRB 210923B, at 2021-09-23 02:11:29.000 UTC (denoted as T0),
which was also detected by Konus-Wind.
According to the GECAM-B light curves in about 15-3500 keV, this 
burst mainly consists of a broad pulse with a duration of about 0.679 s.

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/utn210923_021129_GECAMb_lc.png

GECAM-B localized this burst to the following position (J2000):
Ra: 287.25 deg 
Dec: -12.03 deg
Err: 6.29 deg (1-sigma, statistical only)
The current systematic error of location is estimated to be several degrees 
which could be minimized by the ongoing calibration.

Please note that all GECAM results here are preliminary. The final analysis
will be published in journal papers or GECAM online catalog.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor
(GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in
Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time),
which was funded by the Chinese Academy of Sciences (CAS).


GRB_name: GRB210924A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30878
SUBJECT: GRB 210924A: Fermi GBM Final Real-time Localization
DATE:    21/09/24 23:13:09 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely SHORT GRB

At 23:02:52 UT on 24 Sep 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210924A (trigger 654217377.138008 / 210924960).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 107.1, Dec = 45.3 (J2000 degrees, equivalent to J2000 07h 08m, 45d 17'), with a statistical uncertainty of 10.5 degrees.

The angle from the Fermi LAT boresight is 22.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210924960/quicklook/glg_skymap_all_bn210924960.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210924960/quicklook/glg_healpix_all_bn210924960.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210924960/quicklook/glg_lc_medres34_bn210924960.gif


GRB_name: GRB210919A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30879
SUBJECT: GRB 210919A: Chandra rapid ToO upper limit
DATE:    21/09/25 01:27:01 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

T. Sakamoto (AGU), E. Troja (NASA/GSFC/ORAU), J. Norris (BSU),
S. D. Barthelmy (GSFC), J. L. Racusin (GSFC), N. Kawai (Tokyo Tech),
A. Fruchter (STScI), M. Im (SNU), B. Cenko (GSFC)

A Chandra ToO observation of a short GRB 200919A (Tohuvavohu et al., GCN Circ. 30846)
started on February 21 02:54 UT (~2.1 days after the GRB trigger) for a total of 19.8 ksec.

We do not detect an X-ray afterglow at the location of the enhanced XRT position
(Goad et al., GCN Circ. 30850).  The calculated 3-sigma upper limit is 3.4 x 10^-4 c/s
in the 0.3-8 keV band using aprates of the CIAO software package.  Assuming N_H of
1.5 x 10^21 cm^-2 and photon index of 2, we estimated an 3-sigma unabsorbed flux
upper limit of 6.9 x 10^-15 erg/cm2/s in the 0.3-8 keV band.

We would like to thank Patrick Slane, Harvey Tananbaum, Andrea Prestwich,
and the Chandra operation team for rapidly approving and making this observation.


GRB_name: GRB210925A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30880
SUBJECT: GRB 210925A: Fermi GBM Final Real-time Localization
DATE:    21/09/25 19:22:53 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 19:12:27 UT on 25 Sep 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210925A (trigger 654289952.965146 / 210925800).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 347.4, Dec = -17.1 (J2000 degrees, equivalent to J2000 23h 09m, -17d 06'), with a statistical uncertainty of 3.3 degrees.

The angle from the Fermi LAT boresight is 82.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210925800/quicklook/glg_skymap_all_bn210925800.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210925800/quicklook/glg_healpix_all_bn210925800.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210925800/quicklook/glg_lc_medres34_bn210925800.gif


GRB_name: GRB210925A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30881
SUBJECT: GRB 210925A: GECAM detection
DATE:    21/09/26 09:27:52 GMT
FROM:    Chao Zheng at IHEP  <zhengchao97@ihep.ac.cn>

C. Zheng, S. L. Xiong, S. Xiao, Y. Q. Zhang, W. C. Xue, X. Y. Song,   
X. Y. Zhao, Y. Huang, S. L. Xie, C. Cai, Y. Zhao, Z. W. Guo, 
X. L. Zhang,  C. Y. Li, C. W. Wang, Q. B. Yi, B. X. Zhang, P. Zhang,
W. X. Peng, R. Qiao, D. Y. Guo, X. B. Li, X. Ma, P. Wang, J. Wang, 
Z. Zhang, S. J. Zheng, W. Chen, J. J. He, G. Y. Zhao, Y. Q. Du,
H. Wu, J. Liang, Q. Luo, J. C. Liu,  L. M. Song, F. J. Lu, 
S. N. Zhang (IHEP), report on behalf of GECAM team:

During the commissioning phase, GECAM-B was triggered in-flight by a long
bright burst, GRB 210925A, at 2021-09-25T19:12:34.600 UTC (denoted as T0),
which was also detected by Fermi/GBM (GCN #30880).

Its alert data was promptly downlinked to the ground through the short
message service of BeiDou Navigation Satellite System (BDS). The time
latency of the first BeiDou message relative to the trigger time is about
1 minute.

According to the BDS alert data, this burst mainly consists of multiple
pulses with duration of about 10 s. 

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/utn210925_191234_GECAMb.png

An automatic in-flight localization was calculated using the light curves 
and spectrum. Although the in-flight calibration of energy response and l
ocalization has not been finalized yet, GECAM-B localized this burst to 
the following position (J2000): 
Ra: 357.83 deg 
Dec: -24.58 deg
Err: 3.50 deg (1-sigma, statistical only)
The current systematic error of location is estimated to be several degrees 
which could be minimized by the ongoing calibration.

Please note that all GECAM results here are preliminary. The final analysis
will be published in journal papers or GECAM online catalog.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor
(GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in
Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time),
which was funded by the Chinese Academy of Sciences (CAS).


GRB_name: GRB210919A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30883
SUBJECT: GRB 210919A CAHA 2.2m Observations: Afterglow/Host Galaxy Candidate
DATE:    21/09/26 22:58:23 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

D. A. Kann (HETH/IAA-CSIC), A. Rossi (INAF-OAS), A. de Ugarte Postigo 
(HETH/IAA-CSIC, DARK/NBI), C. Thoene, M. Blazek, J. F. Agui Fernandez 
(all HETH/IAA-CSIC), and P. Minguez (CAHA) report:

We obtained observations of the enhance XRT position (Goad et al., GCN 
30850) of the Swift short GRB 210919A (Tohuvavohu et al., GCN #30846) 
with CAFOS mounted on the 2.2m telescope at CAHA, Almeria, Spain. We 
obtained 30 x 90 s images in the i' band, starting at 03:38 UT on 
September 19, under good observing conditions.

In the stacked image, we detect a faint source within the enhanced XRT 
error circle at:

RA (J2000)   =  05:21:01.098
Dec. (J2000) = +01:18:43.15

with an error of 0".5.

Compared to three nearby comparison stars from the PanSTARRS catalog, we 
measure:

i' = 24.14 +/- 0.30 mag (AB) @ 0.1525 days after the GRB.

We suggest this source to be either the afterglow or the host galaxy of 
GRB 210919A.

Other teams have reported upper limits so far:

CR > 18.6 @ 0.007824 d (deepest, Lipunov et al., GCN #30847)
CR > 17.5 @ 0.002975 d (Hu et al., GCN #30848)
Rc > 20.5, Ic > 18.7 @ 0.05083 - 0.06958 d (Strausbaugh et al., GCN 
#30849)
Rc > 22.1 @ 0.03194 d (Pankov et al., GCN #30851)
r' > 23.4 @ 0.13125 d, i' > 23.9 @ 0.14458 d (Perley et al., GCN #30852)
Rc > 20.5 @ 0.7208 d (Takamatsu et al., GCN #30855)
Rc > 21.716 @ 0.426 d (AB); r' > 20.16 @ 0.6558 d; i' > 19.107 @ 0.6595 
d (Kim et al., GCN #30856)
white > 20.8 @ 0.001826 d (Siegel et al., GCN #30857)
Kp > 21.5 @ 0.5542 d (AB) (Zhang et al., GCN #30858)
r' > 23.6 @ 2.4635 d (Gottlieb et al., GCN #30860)
i' > 24.1, z' > 23.6 @ 2.343 d (Pierel et al., GCN #30868)

None of these limits are as deep as our image, with the NOT imaging 
(Perley et al., GCN #30852) slightly earlier and the late DeCam imaging 
(Pierel et al., GCN #30868) coming closest. This leaves it unclear as to 
whether the source is fading, we can therefore not discern whether it is 
an afterglow candidate or a host-galaxy candidate.

Deeper imaging is needed, if the source is undetected to deeper limits, 
it is very likely the afterglow. If it is the host, it should be 
detected at higher significance.


GRB_name: GRB210919A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30884
SUBJECT: GRB 210919A OSN 1.5m Source Confirmation
DATE:    21/09/26 23:01:27 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

D. A. Kann (HETH/IAA-CSIC), A. Rossi (INAF-OAS), A. de Ugarte Postigo 
(HETH/IAA-CSIC, DARK/NBI), C. Thoene, M. Blazek, J. F. Agui Fernandez 
(all HETH/IAA-CSIC), and F. Aceituno (IAA) report:

We obtained observations of the enhance XRT position (Goad et al., GCN 
30850) of the Swift short GRB 210919A (Tohuvavohu et al., GCN #30846) 
with the 1.5m telescope of OSN, Granada, Spain. We obtained 35 x 120 s 
images in the Rc band, starting at 03:28:22 UT on September 19, under 
good observing conditions. We obtained a second epoch, with 41 x 120 s 
images, the following night, starting at 2:59:51 UT on September 20.

The source detected by Kann et al. (GCN #30883) is very faintly detected 
in the first epoch.

Using the same comparison stars from the PanSTARRS catalog as used by 
Kann et al. (GCN #30883) (transformed to Rc via the Lupton equations, 
then transformed back to AB magnitudes), we measure:

Rc = 24.47 +/- 0.53 mag @ 0.14944 d after trigger (AB mag).

The source is undetected in the second epoch, but it is shallower, with 
Rc > 23.6 mag (AB) @ 1.13649 d after the GRB. We note this detection is 
also fainter than the upper limits listed in Kann et al. (GCN #30883).


GRB_name: GRB210927A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30885
SUBJECT: GRB 210927A: Fermi GBM Final Real-time Localization
DATE:    21/09/27 00:54:10 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely SHORT GRB

At 00:43:57 UT on 27 Sep 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210927A (trigger 654396242.858592 / 210927031).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 252.1, Dec = 0.0 (J2000 degrees, equivalent to J2000 16h 48m, 0d 00'), with a statistical uncertainty of 20.8 degrees.

The angle from the Fermi LAT boresight is 28.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210927031/quicklook/glg_skymap_all_bn210927031.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210927031/quicklook/glg_healpix_all_bn210927031.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210927031/quicklook/glg_lc_medres34_bn210927031.gif


GRB_name: GRB210926A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30886
SUBJECT: GRB 210926A: GECAM detection
DATE:    21/09/27 05:09:38 GMT
FROM:    Chao Zheng at IHEP  <zhengchao97@ihep.ac.cn>

C. Zheng, S. L. Xiong, X. Y. Zhao, Y. Huang, C. Cai, Z. W. Guo, C. Y. Li,
S. Xiao, S. L. Xie, W. C. Xue, Q. B. Yi, Y. Zhao, Y. Q. Zhang, J. C. Liu,
X. Y. Song, X. B. Li, P. Wang, J. Wang,  Q. Luo, W. Chen, J. J. He, H. Wu,
X. L. Zhang, C. W. Wang, P. Zhang, W. X. Peng, R. Qiao, D. Y. Guo, X. Ma, 
S. J. Zheng, G. Y. Zhao, Y. Q. Du, J. Liang, Z. Zhang, L. M. Song, 
F. J. Lu, S. N. Zhang (IHEP), report on behalf of GECAM team:

During the commissioning phase, GECAM-B was triggered in-flight by a long
burst, GRB 210926A, at 2021-09-26T20:52:28.250 UTC (denoted as T0). 
This burst consists of two episodes, with the first one triggered by
Fermi/GBM (trigger ID: 654382283). Both episodes were triggered by
GECAM-B with the on-ground pipeline.

Its alert data was promptly downlinked to the ground through the short
message service of BeiDou Navigation Satellite System (BDS). The time
latency of the first BeiDou message relative to the trigger time is about
1 minute.

According to the BDS alert data, this burst mainly consists of multiple
pulses with duration of about 90 s. 

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/GRB_210926A.png

GECAM-B localized this burst to the following position (J2000): 
Ra: 351.51 deg 
Dec: -18.21 deg
Err: 2.86 deg (1-sigma, statistical only)
The current systematic error of location is estimated to be several degrees 
which could be minimized by the ongoing calibration.

The GECAM preliminary location could be found here: 
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/210926Aloc.png

This location is consistent with Fermi/GBM position within the error.

Please note that all GECAM results here are preliminary. The final analysis
will be published in journal papers or GECAM online catalog.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor
(GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in
Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time),
which was funded by the Chinese Academy of Sciences (CAS).


GRB_name: GRB210919A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30888
SUBJECT: GRB 210919A: iTelescope T-11 upper limits
DATE:    21/09/27 09:23:47 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

K. Hasuda, T. Sakamoto (AGU)

We observed the field of GRB 210919A detected by Swift
(Tohuvavohu et al., GCN Circ. 30846) with the iTelescope.Net
(http://www.itelescope.net) T11 (Planewave 20" CDK) telescope
located at the New Mexico Skies Observatory (NM, USA).
59 images of 60 sec exposures were taken in the R filter
starting from September 21 on 10:04:47 (UT) about 2.4 days after
the trigger and stopped on 11:26:12 (UT).  We further obtained
60 images of 60 sec exposures in the R filter starting from
September 22 on 10:01:34.4 (UT) and stopped on 11:27:50 (UT).

We do not detect the optical afterglow both in the individual
images and the stacked image at the XRT position
(Goad et al., GCN Circ. 30850).  The estimated five sigma
upper limits of the combined image of the first observation
(total exposure of 3540 sec) and the second observation (total
exposure of 3600 sec) are 17.8 and 19.1 using the USNO-B1 catalog.


GRB_name: GRB210926A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30889
SUBJECT: GRB 210926A: AstroSat CZTI detection
DATE:    21/09/27 13:36:09 GMT
FROM:    Gaurav Waratkar at IIT,Bombay  <gauravwaratkar@iitb.ac.in>

P. Sawant (IUCAA), G. Waratkar (IITB), V. Prasad (IUCAA), A. Vibhute
(IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao
(IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat
CZTI collaboration: 

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al.,
2021, JApA, 42, 73) showed detection of a long GRB 210926A, which was
also detected by GECAM (C. Zheng et al., GCN 30886).

The source was clearly detected in the 20-200 keV energy range. The
light curve showed multiple peaks of emission with the strongest peak at
2021-09-26 20:52:27.5 UT. The measured peak count rate associated with
the burst is 250 (+51, -16) cts/s above the background in the combined
data of four quadrants, with a total of 3971 (+446, -463) cts. The local
mean background count rate was 480 (+3, -3) cts/s. Using cumulative
rates, we measure a T90 of 26 (+6, -5) s. 

It was also clearly detected in the CsI anticoincidence (Veto) detector
in the 100-500 keV energy range. The light curve showed multiple peaks
of emission with the strongest peak at 2021-09-26 20:52:30.9 UT. The
measured peak count rate is 262 (+73, -38) cts/s above the background in
the combined Veto data of four quadrants, with a total of 3091 (+703,
-866 cts. The local mean background count rate was 1512 (+5, -4) cts/s.
We measure a T90 of 25 (+14, -10) s from the cumulative Veto light
curve. 

CZTI GRB detections are reported regularly on the payload site at
http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led
consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC,
and PRL. The Indian Space Research Organisation funded, managed and
facilitated the project.


GRB_name: GRB210925B
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30890
SUBJECT: IPN triangulation of GRB 210925B
DATE:    21/09/27 18:08:46 GMT
FROM:    Anna Ridnaia at Ioffe Institute  <ridnaia@mail.ioffe.ru>

K. Hurley, on behalf of the IPN,

I. G. Mitrofanov, D. V. Golovin, A. S. Kozyrev, M. L. Litvak,
and A. B. Sanin, on behalf of the HEND-Odyssey GRB team,

A. Ridnaia, S. Golenetskii, D. Frederiks, D. Svinkin,
A. Lysenko, and T. Cline on behalf of the Konus-Wind team,

A. Goldstein, M. S. Briggs, and C. Wilson-Hodge
on behalf of the Fermi-GBM team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu
on behalf of the Swift-BAT team, and

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:

The long-duration GRB 210925B
was detected by Fermi (GBM trigger 654225613), Konus-Wind,
Mars-Odyssey (HEND), INTEGRAL (SPI-ACS), and Swift-BAT
at about 4809 s UT (01:20:09).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
 ---------------------------------------------
  RA(2000), deg                 Dec(2000), deg
 ---------------------------------------------
 Center:
   48.817 (03h 15m 16s) -52.863 (-52d 51' 45")
 Corners:
   47.551 (03h 10m 12s) -53.723 (-53d 43' 21")
   50.006 (03h 20m 01s) -52.058 (-52d 03' 29")
   50.027 (03h 20m 06s) -51.978 (-51d 58' 41")
   47.579 (03h 10m 19s) -53.644 (-53d 38' 39")
 ---------------------------------------------
The error box area is 335 sq. arcmin, and its maximum
dimension is 2.3 deg (the minimum one is 2.5 arcmin).
The Sun distance was 113 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB210925_T04810/IPN/

The time history and spectrum will be given in forthcoming GCN Circulars.


GRB_name: GRB210925B
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30892
SUBJECT: GRB 210925B: AstroSat CZTI detection
DATE:    21/09/28 13:24:23 GMT
FROM:    Gaurav Waratkar at IIT,Bombay  <gauravwaratkar@iitb.ac.in>

V. Prasad (IUCAA), P. Sawant (IUCAA), G. Waratkar (IITB), A. Vibhute
(IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao
(IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat
CZTI collaboration: 

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al.,
2021, JApA, 42, 73) showed detection of a long GRB 210925B for which the
IPN triangulation (Hurley et al., GCN 30890) was reported. 

The source was clearly detected in the 20-200 keV energy range. The
light curve showed multiple peaks of emission with the strongest peak at
2021-09-25 01:20:09.75 UT. The measured peak count rate associated with
the burst is 887 (+190, -97) cts/s above the background in the combined
data of four quadrants, with a total of 1482 (+214, -230) cts. The local
mean background count rate was 471 (+5, -9) cts/s. Using cumulative
rates, we measure a T90 of 6.3 (+1.9, -2.0) s. 

It was also clearly detected in the CsI anticoincidence (Veto) detector
in the 100-500 keV energy range. 

CZTI GRB detections are reported regularly on the payload site at
http://astrosat.iucaa.in/czti/?q=grb. CZTI is built by a TIFR-led
consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC,
and PRL. The Indian Space Research Organisation funded, managed, and
facilitated the project.


GRB_name: GRB210927A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30893
SUBJECT: GRB 210927A: Zwicky Transient Facility Follow-Up of a Fermi Short GRB (Trigger 654396242) 
DATE:    21/09/28 20:28:28 GMT
FROM:    Shreya Anand at GROWTH Caltech  <sanand@caltech.edu>

Shreya Anand (Caltech), Tomas Ahumada (UMD), Harsh Kumar (IITB), Michael Coughlin (UMN), Ana Sagues-Carracedo (OKC), Mansi M. Kasliwal (Caltech), Erik Kool (OKC), Simeon Reusch (DESY), Robert Stein (DESY), Igor Andreoni (UMD), Varun Bhalerao (IITB), Albert Kong (NTHU), Leo Singer(NASA/GSFC), Jannis Necker (DESY), and Sven Weimann (DESY)
on behalf of the Zwicky Transient Facility (ZTF) collaboration

We observed the localization region of the short GRB 210927A (trigger 654396242) detected by the Gamma-Ray Burst Monitor (GBM) on the Fermi satellite with the Palomar 48 inch telescope equipped with the 47 square degree Zwicky Transient Facility (ZTF) camera. We obtained a series of g- and r-band images covering 470 square degrees beginning at 02:32 UT on 2021 Sept. 27 (1:38 hours after the burst trigger time) and repeating the same observing plan the next night. This corresponds to ~44% of the probability enclosed in the Earth-occultation corrected GRB localization map (GCN 30885). Each exposure was 240 seconds, reaching g-band and r-band median depths of 22.1 mag and 21.9 mag respectively for the first night and 21.4 mag and 21.3 mag for the second night. The images were processed in real-time through the ZTF reduction and image subtraction pipelines at IPAC (Masci et al. 2019).

We queried the ZTF alert stream using Kowalski (Duev et al. 2019). We required at least 2 detections separated by at least 15 minutes to select against moving objects. Furthermore, we cross-match our candidates with the Minor Planet Center to flag known asteroids, reject stellar sources (Tachibana and Miller 2018), and apply machine learning algorithms (Mahabal et al. 2019). We require that no spatially coincident ZTF alerts were issued before the detection time of the GBM trigger. We also require sources to fade faster than 0.3 mag/day to be of interest. The candidates within the 90% probability contour of the GRB localization map that pass these selection criteria as well as human vetting are presented in the table below. The filter, magnitude and MJD columns correspond to the ZTF first alert, while the Decline Rate (D.R) is in [mag/day]. The first four of these candidates also passed the ZTF Realtime Search and Triggering pipeline (Andreoni et al. 2021), which identifies rapidly-evolving candidates in the ZTF alert stream. 

+----------------------------------------------------------------------------------------------------------------------+
| ZTF Name | IAU Name | RA (deg) | DEC (deg) | r-band Mag | magErr | D.R. [mag/day] | Notes  |
+----------------------------------------------------------------------------------------------------------------------+
ZTF21acdvumo | AT2021zwo | 244.806185 | 10.4431253 | 21.40 | 0.12 | D.R. g-band = 0.38 | (a)(1)
ZTF21acdvuvw | AT2021zwp | 234.359624 | 21.0864387 | 21.10 | 0.14 | D.R. r-band = 0.43 | (a)(2)
ZTF21acdvwoe | AT2021zwq | 249.160939 | 11.5012227 | 21.15 | 0.13 | D.R. r-band = 0.35 | (b)
ZTF21acdwbpx | AT2021zwr | 258.470967 | 7.9687908 | 20.85 | 0.13 | D.R. r-band = 0.73 | (b)
ZTF21acdwctm | AT2021zws | 267.270437 | -3.3173181 | 20.95 | 0.10 | D.R. r-band = 0.37 | (c)
+----------------------------------------------------------------------------------------------------------------------+


Notes:
(a) offset from a galaxy
(b) PSF-like based on Legacy Survey (LS) DR9 classification
(c) hostless; low galactic latitude b=12.26; D.R. obtained with GROWTH-India telescope photometry

(1) LS phot-z = 0.253 +/- 0.099
(2) LS phot-z = 0.116 +/- 0.217


ZTF and GROWTH are worldwide collaborations comprising Caltech, USA; IPAC, USA, WIS, Israel; OKC, Sweden; JSI/UMd, USA; U Washington, USA; DESY,
Germany; MOST, Taiwan; UW Milwaukee, USA; LANL USA; Tokyo Tech, Japan; IITB, India; IIA, India; LJMU, UK; TTU, USA; SDSU, USA and USyd, Australia.
ZTF acknowledges the generous support of the NSF under AST MSIP Grant No 1440341.
GROWTH acknowledges generous support of the NSF under PIRE Grant No 1545949.
Alert distribution service provided by DIRAC@UW (Patterson et al. 2019).
Alert database searches are done by AMPEL (Nordin et al. 2019) and Kowalski (Duev et al. 2019). GROWTH India telescope is located at the Indian Astronomical Observatory (Hanle), operated by the Indian Institute of Astrophysics (IIA). GROWTH-India project is supported by SERB and administered by IUSSTF, under grant number IUSSTF/PIRE Program/GROWTH/2015-16 and IUCAA.


GRB_name: GRB210929A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30894
SUBJECT: GRB 210929A: Fermi GBM Final Real-time Localization
DATE:    21/09/29 03:51:22 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely SHORT GRB

At 03:41:39 UT on 29 Sep 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210929A (trigger 654579704.256098 / 210929154).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 317.8, Dec = 12.3 (J2000 degrees, equivalent to J2000 21h 11m, 12d 18'), with a statistical uncertainty of 14.1 degrees.

The angle from the Fermi LAT boresight is 67.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210929154/quicklook/glg_skymap_all_bn210929154.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210929154/quicklook/glg_healpix_all_bn210929154.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210929154/quicklook/glg_lc_medres34_bn210929154.gif


GRB_name: GRB210929B
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30896
SUBJECT: GRB 210929B: Fermi GBM Final Real-time Localization
DATE:    21/09/29 19:53:46 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 19:42:22 UT on 29 Sep 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210929B (trigger 654637347.41104 / 210929821).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 263.0, Dec = 2.4 (J2000 degrees, equivalent to J2000 17h 32m, 2d 23'), with a statistical uncertainty of 13.3 degrees.

The angle from the Fermi LAT boresight is 70.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210929821/quicklook/glg_skymap_all_bn210929821.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210929821/quicklook/glg_healpix_all_bn210929821.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210929821/quicklook/glg_lc_medres34_bn210929821.gif


GRB_name: GRB210930A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30897
SUBJECT: GRB 210930A: Swift detection of a burst
DATE:    21/09/30 02:58:45 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <siegel@swift.psu.edu>

V. D'Elia (SSDC & INAF-OAR), E. Ambrosi (INAF-IASFPA),
S. Laha (GSFC/UMBC/CRESST), A. Y. Lien (U Tampa),
F. E. Marshall (NASA/GSFC), D. M. Palmer (LANL), M. H. Siegel (PSU)
and A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels
Swift Observatory Team:

At 02:46:52 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210930A (trigger=1075565).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 197.435, +48.623 which is 
   RA(J2000) = 13h 09m 44s
   Dec(J2000) = +48d 37' 22"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 15 sec.  The peak count rate
was ~800 counts/sec (15-350 keV), at ~8 sec after the trigger. 

The XRT began observing the field at 02:49:12.3 UT, 140.1 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source located at RA, Dec 197.40185, 48.62853 which
is equivalent to:
   RA(J2000)  = 13h 09m 36.44s
   Dec(J2000) = +48d 37' 42.7"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 81 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at https://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (9.55 x
10^19 cm^-2, Willingale et al. 2013), with an excess column of 6.4
(+3.87/-3.20) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 143 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image covers none of
the XRT error circle. The 8'x8' region for the list of sources generated
on-board covers 100% of the XRT error circle. The list of sources is typically
complete to about 18 mag. No correction has been made for the expected
extinction corresponding to E(B-V) of 0.010. 

Burst Advocate for this burst is V. D'Elia (valerio.delia AT ssdc.asi.it). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)


GRB_name: GRB210929B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30898
SUBJECT: Fermi GRB 210929B: Global MASTER-Net observations report 
DATE:    21/09/30 09:15:21 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev, O.Ershova 
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

V. Yurkov, A. Gabovich, Yu. Sergienko 
(Blagoveschensk Educational State University)




MASTER-OAFA robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 210929B ( Fermi GBM team, GCN 30896) errorbox  12960 sec after notice time and 13009 sec after trigger time at 2021-09-29 23:19:12 UT, with upper limit up to  18.1 mag. Observations started at twilight.  The observations began at zenith distance = 43 deg. The sun  altitude  is -10.2 deg. 

The galactic latitude b = 18 deg., longitude l = 26 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1737410

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

   13040 | 2021-09-29 23:19:12 |         MASTER-OAFA | (17h 23m 50.65s , +02d 25m 39.2s) |   C |    60 | 16.4 |        
   13122 | 2021-09-29 23:20:34 |         MASTER-OAFA | (17h 31m 43.25s , +02d 24m 27.5s) |   C |    60 | 16.4 |        
   13202 | 2021-09-29 23:21:54 |         MASTER-OAFA | (17h 22m 28.05s , +00d 32m 38.6s) |   C |    60 | 16.6 |        
   13281 | 2021-09-29 23:23:13 |         MASTER-OAFA | (17h 30m 27.82s , +00d 30m 33.6s) |   C |    60 | 16.8 |        
   13360 | 2021-09-29 23:24:32 |         MASTER-OAFA | (17h 26m 12.96s , +04d 19m 40.6s) |   C |    60 | 16.9 |        
   13440 | 2021-09-29 23:25:52 |         MASTER-OAFA | (17h 34m 14.62s , +04d 20m 28.5s) |   C |    60 | 16.9 |        
   13520 | 2021-09-29 23:27:11 |         MASTER-OAFA | (17h 22m 14.54s , -01d 23m 18.2s) |   C |    60 | 17.1 |        
   13599 | 2021-09-29 23:28:31 |         MASTER-OAFA | (17h 30m 21.22s , -01d 23m 20.2s) |   C |    60 | 17.2 |        
   13678 | 2021-09-29 23:29:50 |         MASTER-OAFA | (17h 39m 00.24s , +02d 24m 22.4s) |   C |    60 | 17.1 |        
   13758 | 2021-09-29 23:31:10 |         MASTER-OAFA | (17h 47m 03.30s , +02d 25m 58.1s) |   C |    60 | 17.1 |        
   13838 | 2021-09-29 23:32:30 |         MASTER-OAFA | (17h 37m 36.22s , +00d 32m 18.2s) |   C |    60 | 17.5 |        
   13921 | 2021-09-29 23:33:53 |         MASTER-OAFA | (17h 45m 42.18s , +00d 31m 05.0s) |   C |    60 | 17.6 |        
   14000 | 2021-09-29 23:35:12 |         MASTER-OAFA | (17h 23m 43.05s , +02d 24m 41.0s) |   C |    60 | 17.5 |        
   14080 | 2021-09-29 23:36:32 |         MASTER-OAFA | (17h 31m 50.09s , +02d 24m 40.7s) |   C |    60 | 17.5 |        
   14159 | 2021-09-29 23:37:51 |         MASTER-OAFA | (17h 22m 28.08s , +00d 32m 37.6s) |   C |    60 | 17.6 |        
   14239 | 2021-09-29 23:39:11 |         MASTER-OAFA | (17h 30m 27.90s , +00d 30m 28.9s) |   C |    60 | 17.6 |        
   14318 | 2021-09-29 23:40:30 |         MASTER-OAFA | (17h 26m 17.60s , +04d 20m 23.9s) |   C |    60 | 17.7 |        
   14397 | 2021-09-29 23:41:49 |         MASTER-OAFA | (17h 34m 13.83s , +04d 19m 25.5s) |   C |    60 | 17.6 |        
   14477 | 2021-09-29 23:43:09 |         MASTER-OAFA | (17h 22m 15.63s , -01d 21m 21.6s) |   C |    60 | 17.8 |        
   14556 | 2021-09-29 23:44:28 |         MASTER-OAFA | (17h 30m 21.24s , -01d 22m 35.0s) |   C |    60 | 17.8 |        
   14636 | 2021-09-29 23:45:47 |         MASTER-OAFA | (17h 38m 56.30s , +02d 24m 14.4s) |   C |    60 | 17.7 |        
   14718 | 2021-09-29 23:47:10 |         MASTER-OAFA | (17h 47m 02.98s , +02d 24m 26.4s) |   C |    60 | 17.6 |        
   14797 | 2021-09-29 23:48:29 |         MASTER-OAFA | (17h 37m 39.84s , +00d 31m 50.6s) |   C |    60 | 17.7 |        
   14881 | 2021-09-29 23:49:53 |         MASTER-OAFA | (17h 45m 40.02s , +00d 30m 10.5s) |   C |    60 | 17.7 |        
   14961 | 2021-09-29 23:51:12 |         MASTER-OAFA | (17h 23m 48.72s , +02d 26m 27.8s) |   C |    60 | 17.7 |        
   15040 | 2021-09-29 23:52:32 |         MASTER-OAFA | (17h 31m 44.29s , +02d 25m 22.9s) |   C |    60 | 17.6 |        
   15119 | 2021-09-29 23:53:51 |         MASTER-OAFA | (17h 22m 25.36s , +00d 32m 35.7s) |   C |    60 | 17.7 |        
   15204 | 2021-09-29 23:55:16 |         MASTER-OAFA | (17h 30m 31.02s , +00d 31m 22.3s) |   C |    60 | 17.7 |        
   15283 | 2021-09-29 23:56:35 |         MASTER-OAFA | (17h 26m 12.73s , +04d 18m 32.0s) |   C |    60 | 17.7 |        
   15363 | 2021-09-29 23:57:55 |         MASTER-OAFA | (17h 34m 20.24s , +04d 18m 31.0s) |   C |    60 | 17.6 |        
   15442 | 2021-09-29 23:59:14 |         MASTER-OAFA | (17h 22m 17.61s , -01d 21m 52.2s) |   C |    60 | 18.0 |        
   15523 | 2021-09-30 00:00:34 |         MASTER-OAFA | (17h 30m 17.50s , -01d 23m 37.6s) |   C |    60 | 17.8 |        
   15607 | 2021-09-30 00:01:59 |         MASTER-OAFA | (17h 39m 03.44s , +02d 25m 43.2s) |   C |    60 | 17.7 |        
   15686 | 2021-09-30 00:03:18 |         MASTER-OAFA | (17h 46m 58.28s , +02d 24m 54.3s) |   C |    60 | 17.5 |        
   15767 | 2021-09-30 00:04:39 |         MASTER-OAFA | (17h 37m 37.58s , +00d 32m 06.8s) |   C |    60 | 17.8 |        
   15849 | 2021-09-30 00:06:01 |         MASTER-OAFA | (17h 45m 42.52s , +00d 30m 53.3s) |   C |    60 | 17.7 |        
   15929 | 2021-09-30 00:07:21 |         MASTER-OAFA | (17h 29m 56.23s , +06d 12m 30.6s) |   C |    60 | 17.5 |        
   16009 | 2021-09-30 00:08:41 |         MASTER-OAFA | (17h 37m 57.28s , +06d 13m 48.9s) |   C |    60 | 17.5 |        
   16089 | 2021-09-30 00:10:01 |         MASTER-OAFA | (17h 14m 36.49s , +06d 14m 39.2s) |   C |    60 | 17.8 |        
   16169 | 2021-09-30 00:11:21 |         MASTER-OAFA | (17h 22m 34.67s , +06d 13m 33.3s) |   C |    60 | 17.6 |        
   16248 | 2021-09-30 00:12:40 |         MASTER-OAFA | (17h 08m 35.85s , +02d 25m 52.5s) |   C |    60 | 17.8 |        
   16331 | 2021-09-30 00:14:03 |         MASTER-OAFA | (17h 16m 31.55s , +02d 24m 39.5s) |   C |    60 | 17.9 |        
   16411 | 2021-09-30 00:15:23 |         MASTER-OAFA | (17h 10m 58.78s , +04d 20m 38.2s) |   C |    60 | 17.9 |        
   16491 | 2021-09-30 00:16:43 |         MASTER-OAFA | (17h 19m 00.96s , +04d 19m 04.4s) |   C |    60 | 17.8 |        
   16570 | 2021-09-30 00:18:02 |         MASTER-OAFA | (17h 07m 11.44s , +00d 31m 52.8s) |   C |    60 | 18.0 |        
   16649 | 2021-09-30 00:19:21 |         MASTER-OAFA | (17h 15m 11.80s , +00d 32m 39.6s) |   C |    60 | 17.8 |        
   16729 | 2021-09-30 00:20:41 |         MASTER-OAFA | (17h 37m 26.07s , -01d 23m 57.8s) |   C |    60 | 17.7 |        
   16808 | 2021-09-30 00:22:00 |         MASTER-OAFA | (17h 45m 33.56s , -01d 24m 00.7s) |   C |    60 | 17.7 |        
   16888 | 2021-09-30 00:23:20 |         MASTER-OAFA | (17h 29m 53.36s , +06d 13m 55.8s) |   C |    60 | 17.7 |        
   16969 | 2021-09-30 00:24:41 |         MASTER-OAFA | (17h 37m 56.96s , +06d 12m 11.1s) |   C |    60 | 17.6 |        
   17049 | 2021-09-30 00:26:00 |         MASTER-OAFA | (17h 14m 36.31s , +06d 14m 15.1s) |   C |    60 | 17.9 |        
   17129 | 2021-09-30 00:27:20 |         MASTER-OAFA | (17h 22m 35.63s , +06d 13m 27.3s) |   C |    60 | 17.9 |        
   17208 | 2021-09-30 00:28:40 |         MASTER-OAFA | (17h 08m 29.57s , +02d 26m 48.6s) |   C |    60 | 17.8 |        
   17288 | 2021-09-30 00:30:00 |         MASTER-OAFA | (17h 16m 37.24s , +02d 25m 35.2s) |   C |    60 | 17.9 |        
   17367 | 2021-09-30 00:31:19 |         MASTER-OAFA | (17h 10m 54.99s , +04d 18m 43.0s) |   C |    60 | 17.8 |        
   17447 | 2021-09-30 00:32:39 |         MASTER-OAFA | (17h 19m 02.63s , +04d 18m 59.2s) |   C |    60 | 17.9 |        
   17529 | 2021-09-30 00:34:01 |         MASTER-OAFA | (17h 07m 14.46s , +00d 32m 42.1s) |   C |    60 | 18.1 |        
   17609 | 2021-09-30 00:35:21 |         MASTER-OAFA | (17h 15m 14.54s , +00d 30m 47.5s) |   C |    60 | 17.7 |        
   17688 | 2021-09-30 00:36:40 |         MASTER-OAFA | (17h 37m 32.70s , -01d 22m 05.9s) |   C |    60 | 17.8 |        
   17772 | 2021-09-30 00:38:04 |         MASTER-OAFA | (17h 45m 26.18s , -01d 23m 16.1s) |   C |    60 | 17.8 |        
   17852 | 2021-09-30 00:39:24 |         MASTER-OAFA | (17h 29m 50.73s , +06d 14m 09.9s) |   C |    60 | 17.5 |        
   17932 | 2021-09-30 00:40:43 |         MASTER-OAFA | (17h 37m 59.45s , +06d 12m 57.8s) |   C |    60 | 17.6 |        
   18011 | 2021-09-30 00:42:03 |         MASTER-OAFA | (17h 14m 30.70s , +06d 12m 31.9s) |   C |    60 | 17.8 |        
   18090 | 2021-09-30 00:43:22 |         MASTER-OAFA | (17h 22m 40.17s , +06d 12m 44.5s) |   C |    60 | 17.7 |        
   18172 | 2021-09-30 00:44:44 |         MASTER-OAFA | (17h 08m 31.96s , +02d 26m 42.5s) |   C |    60 | 17.5 |        
   18252 | 2021-09-30 00:46:04 |         MASTER-OAFA | (17h 16m 32.74s , +02d 24m 33.4s) |   C |    60 | 17.6 |        
   18342 | 2021-09-30 00:47:34 |         MASTER-OAFA | (17h 11m 00.18s , +04d 20m 09.3s) |   C |    60 | 17.9 |        
   18422 | 2021-09-30 00:48:54 |         MASTER-OAFA | (17h 18m 57.06s , +04d 19m 24.5s) |   C |    60 | 17.9 |        
   18502 | 2021-09-30 00:50:14 |         MASTER-OAFA | (17h 07m 10.73s , +00d 32m 45.5s) |   C |    60 | 18.1 |        
   18581 | 2021-09-30 00:51:33 |         MASTER-OAFA | (17h 15m 18.00s , +00d 31m 32.4s) |   C |    60 | 17.6 |        
   18661 | 2021-09-30 00:52:53 |         MASTER-OAFA | (17h 37m 26.15s , -01d 24m 04.4s) |   C |    60 | 17.7 |        
   18740 | 2021-09-30 00:54:12 |         MASTER-OAFA | (17h 45m 31.92s , -01d 23m 56.4s) |   C |    60 | 17.8 |        
   18826 | 2021-09-30 00:55:38 |         MASTER-OAFA | (17h 41m 29.29s , +04d 18m 05.1s) |   C |    60 | 17.6 |        
   18905 | 2021-09-30 00:56:57 |         MASTER-OAFA | (17h 49m 33.99s , +04d 19m 22.2s) |   C |    60 | 17.7 |        
   18985 | 2021-09-30 00:58:17 |         MASTER-OAFA | (17h 23m 12.41s , -03d 15m 40.9s) |   C |    60 | 18.0 |        
   19064 | 2021-09-30 00:59:36 |         MASTER-OAFA | (17h 31m 18.53s , -03d 16m 55.6s) |   C |    60 | 17.9 |        
   19143 | 2021-09-30 01:00:55 |         MASTER-OAFA | (17h 07m 05.65s , -01d 23m 03.8s) |   C |    60 | 17.9 |        
   19225 | 2021-09-30 01:02:17 |         MASTER-OAFA | (17h 15m 03.93s , -01d 21m 58.3s) |   C |    60 | 17.6 |        
   19304 | 2021-09-30 01:03:36 |         MASTER-OAFA | (17h 38m 30.93s , -03d 16m 12.6s) |   C |    60 | 17.7 |        
   19384 | 2021-09-30 01:04:56 |         MASTER-OAFA | (17h 46m 26.63s , -03d 17m 23.7s) |   C |    60 | 17.7 |        
   19463 | 2021-09-30 01:06:15 |         MASTER-OAFA | (17h 08m 04.15s , -03d 16m 15.6s) |   C |    60 | 17.6 |        
   19622 | 2021-09-30 01:08:54 |         MASTER-OAFA | (17h 45m 11.02s , +06d 13m 32.1s) |   C |    60 | 16.4 |        
   19704 | 2021-09-30 01:10:16 |         MASTER-OAFA | (17h 53m 14.73s , +06d 11m 47.8s) |   C |    60 | 17.2 |        
   19784 | 2021-09-30 01:11:36 |         MASTER-OAFA | (17h 41m 31.64s , +04d 19m 18.8s) |   C |    60 | 17.2 |        
   19863 | 2021-09-30 01:12:55 |         MASTER-OAFA | (17h 49m 28.13s , +04d 18m 27.3s) |   C |    60 | 17.3 |        
   19943 | 2021-09-30 01:14:15 |         MASTER-OAFA | (17h 23m 11.95s , -03d 15m 45.3s) |   C |    60 | 17.4 |        
   20023 | 2021-09-30 01:15:35 |         MASTER-OAFA | (17h 31m 19.22s , -03d 16m 59.6s) |   C |    60 | 17.4 |        
   20102 | 2021-09-30 01:16:54 |         MASTER-OAFA | (17h 07m 00.53s , -01d 23m 18.6s) |   C |    60 | 17.2 |        
   20182 | 2021-09-30 01:18:14 |         MASTER-OAFA | (17h 15m 05.71s , -01d 23m 30.1s) |   C |    60 | 17.4 |        
   20262 | 2021-09-30 01:19:34 |         MASTER-OAFA | (17h 38m 28.42s , -03d 16m 25.7s) |   C |    60 | 17.6 |        
   20342 | 2021-09-30 01:20:54 |         MASTER-OAFA | (17h 46m 28.79s , -03d 18m 25.8s) |   C |    60 | 17.5 |        
   20422 | 2021-09-30 01:22:13 |         MASTER-OAFA | (17h 08m 04.50s , -03d 15m 18.3s) |   C |    60 | 16.7 |        
   20583 | 2021-09-30 01:24:55 |         MASTER-OAFA | (17h 45m 08.07s , +06d 13m 25.9s) |   C |    60 | 17.0 |        
   20664 | 2021-09-30 01:26:16 |         MASTER-OAFA | (17h 53m 17.15s , +06d 12m 13.6s) |   C |    60 | 17.5 |        
   20743 | 2021-09-30 01:27:35 |         MASTER-OAFA | (17h 41m 26.12s , +04d 17m 32.4s) |   C |    60 | 17.2 |        
   20823 | 2021-09-30 01:28:55 |         MASTER-OAFA | (17h 49m 33.76s , +04d 17m 20.4s) |   C |    60 | 17.4 |        
   20903 | 2021-09-30 01:30:15 |         MASTER-OAFA | (17h 23m 14.78s , -03d 16m 08.9s) |   C |    60 | 17.6 |        
   20982 | 2021-09-30 01:31:34 |         MASTER-OAFA | (17h 31m 15.19s , -03d 17m 56.5s) |   C |    60 | 17.4 |        
   21062 | 2021-09-30 01:32:54 |         MASTER-OAFA | (17h 07m 05.52s , -01d 21m 29.8s) |   C |    60 | 16.8 |        
   21146 | 2021-09-30 01:34:18 |         MASTER-OAFA | (17h 14m 59.29s , -01d 22m 34.2s) |   C |    60 | 16.8 |        
   21225 | 2021-09-30 01:35:37 |         MASTER-OAFA | (17h 38m 25.11s , -03d 16m 14.5s) |   C |    60 | 17.2 |        
   21308 | 2021-09-30 01:37:00 |         MASTER-OAFA | (17h 46m 31.64s , -03d 17m 29.8s) |   C |    60 | 17.5 |        
   21400 | 2021-09-30 01:38:32 |         MASTER-OAFA | (17h 07m 57.92s , -03d 17m 16.0s) |   C |    60 | 16.4 |        
   21569 | 2021-09-30 01:41:21 |         MASTER-OAFA | (17h 45m 09.94s , +06d 12m 55.8s) |   C |    60 | 16.4 |        
   21655 | 2021-09-30 01:42:47 |         MASTER-OAFA | (17h 53m 13.64s , +06d 11m 15.5s) |   C |    60 | 17.3 |        
   21734 | 2021-09-30 01:44:06 |         MASTER-OAFA | (17h 19m 14.00s , +08d 06m 49.4s) |   C |    60 | 14.5 |        
   21814 | 2021-09-30 01:45:26 |         MASTER-OAFA | (17h 27m 20.08s , +08d 07m 37.7s) |   C |    60 | 15.5 |        
   21893 | 2021-09-30 01:46:45 |         MASTER-OAFA | (17h 34m 37.80s , +08d 05m 27.0s) |   C |    60 | 15.6 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB210930A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30900
SUBJECT: GRB 210930A: Enhanced Swift-XRT position
DATE:    21/09/30 09:19:07 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.P. Osborne, A.P. Beardmore, P.A. Evans and M.R. Goad (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 1714 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 210930A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 197.40188, +48.62856 which is equivalent
to:

RA (J2000): 13h 09m 36.45s
Dec (J2000): +48d 37' 42.8"

with an uncertainty of 2.4 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB210930A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30901
SUBJECT: Swift GRB 210930A: Global MASTER-Net observations report 
DATE:    21/09/30 16:36:24 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev, O.Ershova 
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

V. Yurkov, A. Gabovich, Yu. Sergienko 
(Blagoveschensk Educational State University)




MASTER-Tavrida robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB 210930A ( V. D'Elia et al., GCN 30897) errorbox  48786 sec after notice time and 48953 sec after trigger time at 2021-09-30 16:22:45 UT, with upper limit up to  17.2 mag. Observations started at twilight.  The observations began at zenith distance = 59 deg. The sun  altitude  is -11.0 deg. 

The galactic latitude b = 68 deg., longitude l = 114 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1737711

We obtain a following upper limits.  

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   32055 |             MASTER- |   C |     1 | 14.1 |        
   32055 |             MASTER- |   C |     1 | 15.1 |        
   36978 |             MASTER- |   C |   180 | 20.0 |        
   49043 |      MASTER-Tavrida |   C |   180 | 17.2 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB210930A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30902
SUBJECT: GRB 210930A: Swift-XRT refined Analysis
DATE:    21/09/30 19:47:41 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A. D'Ai (INAF-IASFPA), A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU),
D.N. Burrows (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U.
Leicester), P.A. Evans (U. Leicester), A. Melandri (INAF-OAB), T.
Sbarrato (INAF-OAB) and V. D'Elia report on behalf of the Swift-XRT
team:

We have analysed 6.3 ks of XRT data for GRB 210930A (D'Elia et al. GCN
Circ. 30897), from 143 s to 52.5 ks after the  BAT trigger. The data
comprise 63 s in Windowed Timing (WT) mode with the remainder in Photon
Counting (PC) mode. The enhanced XRT position for this burst was given
by Osborne et al. (GCN Circ. 30900).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.71 (+0.09, -0.08).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 4.04 (+0.30, -0.27). The
best-fitting absorption column is  1.46 (+0.18, -0.16) x 10^22 cm^-2,
in excess of the Galactic value of 9.6 x 10^19 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.2 (+0.4, -0.3) and
a best-fitting absorption column of 6.1 (+2.4, -2.0) x 10^21 cm^-2. The
counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.7 x 10^-11 (7.5 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      6.1 (+2.4, -2.0) x 10^21 cm^-2
Galactic foreground: 9.6 x 10^19 cm^-2
Excess significance: 5.0 sigma
Photon index:      2.2 (+0.4, -0.3)

If the light curve continues to decay with a power-law decay index of
0.71, the count rate at T+24 hours will be 6.7 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.5 x
10^-13 (5.0 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01075565.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB210930A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30903
SUBJECT: GRB 210930A: Swift/UVOT Upper Limits
DATE:    21/09/30 22:33:53 GMT
FROM:    Alexander Belles at PSU/Swift  <aub1461@psu.edu>

A. Belles (PSU) and V. D'Elia (SSDC & INAF-OAR)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210930A
144 s after the BAT trigger (D'Elia et al., GCN Circ. 30897).
No optical afterglow consistent with the XRT position
(Osborne et al. GCN Circ. 30900)
is detected in the initial UVOT exposures.
Preliminary 3-sigma upper limits using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the first
finding chart (FC) exposure and subsequent exposures are:

Filter         T_start(s)   T_stop(s)      Exp(s)         Mag

white_FC           144          293          147         >19.9
u_FC               302          551          246         >19.6
white              144         1722          411         >20.6
v                  631         1773          136         >18.7
b                  559         1873          134         >19.6
u                  302         1848          363         >19.7
w1                 681         1824          136         >19.5
m2                 655         1450           39         >18.7
w2                 607         1747          117         >20.4

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.010 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB210927A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30908
SUBJECT: GRB 210927A: GIT optical follow-up of ZTF21acdwctm.
DATE:    21/10/01 03:59:51 GMT
FROM:    Harsh Kumar at Indian Inst of Tech,Bombay  <harshkosli13@gmail.com>

H. Kumar(IITB), V. Bhalerao(IITB), J. Stanzin (IAO), G. C. Anupama(IIA), S.
Barway(IIA) report on behalf of the GIT team and the GROWTH Collaboration:

We observed ZTF21acdwctm reported by Shreya Anand et al. (GCN 30893), with 0.7m
GROWTH-India Telescope (GIT). We obtained multiple exposures in the
SDSS r' filter
spanning over 3 nights i.e. 2021-09-28, 2021-09-29, and 2021-09-30. We
clearly detected the afterglow in our stacked images on all 3 nights. The
photometric results follow as:

-------------------------------------------------------------------

 JD (mid) | T_mid-T0(hrs) | Filter | Magnitude (AB) |

-------------------------------------------------------------------

2459486.16719 | 39.28 | r' | 21.32 +/- 0.07

2459487.12169 | 62.19 | r' | 21.59 +/- 0.09

2459488.13340 | 86.47 | r' | 21.92 +/- 0.08

-------------------------------------------------------------------

Based on GIT photometry we can conclude that the candidate is decaying with
a rate of ~0.3 mag/day. A further follow-up of this candidate is highly
encouraged.

The magnitudes are calibrated against PanSTARRS (Flewelling et al., 2018)
and not corrected for Galactic extinction.

The GROWTH India Telescope (GIT) is a 70-cm telescope with a 0.7-degree
field of view, set up by the Indian Institute of Astrophysics (IIA) and the
Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and
IUSSTF. It is located at the Indian Astronomical Observatory (Hanle),
operated by IIA. We acknowledge funding by the IITB alumni batch of 1994,
which partially supports operations of the telescope. Telescope technical
details are available at https://sites.google.com/view/growthindia/.


GRB_name: GRB210930A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30909
SUBJECT: GRB 210930A: CAHA 2.2m telescope optical limit
DATE:    21/10/01 04:35:31 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

Y.-D. Hu, T.-R. Sun, E. Fernandez-Garcia, A. J. Castro-Tirado, M. D. Caballero-Garcia, R. Sanchez-Ramirez, M. A. Castro Tirado (IAA-CSIC) and I. Vico (CAHA) on behalf of a larger collaboration, report:

Following the detection of GRB 210930A by Swift (V. D'Elia et al. GCNC 30897), we triggered the 2.2m CAHA telescope (+ CAFOS) at the Calar Alto Observatory (Almeria, Spain). Images were gathered after the twilight starting on Sep. 30 18:56:50 UT (i.e. 16.2 hour post trigger) in Sloan-gri bands with 90 s exposure each. On the co-added r-band image (6x90s), no optical transient down to 22.6 mag is detected at the X-ray afterglow candidate position reported by Swift/XRT (V. D'Elia et al. GCNC 30897, J.P. Osborne et al. GCNC 30900). This non-detection is consistent with the report from A. Belles et al. (GCNC 30903) and V. Lipunov et al.(GCNC 30901).

We thank the staff at Calar Alto observatory for their excellent support.


GRB_name: GRB210927B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30910
SUBJECT: GRB 210927B: GECAM detection
DATE:    21/10/01 04:47:11 GMT
FROM:    Y Q Zhang at IHEP  <yqzhang@ihep.ac.cn>

J. C. Liu, S. L. Xiong, X. Y. Zhao, Y. Huang, X. Y. Song, C. Cai, S. Xiao,
S. L. Xie, Y. Q. Zhang, Y. Zhao, Z. W. Guo, C. Zheng, W. C. Xue, C. Y. Li,
C. W. Wang, Q. B. Yi, B. X. Zhang, P. Zhang, W. X. Peng, R. Qiao, D. Y. Guo,
X. B. Li, X. Ma, P. Wang, J. Wang, Z. Zhang, S. J. Zheng, W. Chen, J. J. He, 
G. Y. Zhao, Y. Q. Du, H. Wu, J. Liang, Q. Luo, X. L. Zhang, L. M. Song, 
F. J. Lu, S. N. Zhang (IHEP), report on behalf of GECAM team:

During the commissioning phase, GECAM-B was triggered in-flight by a long
burst, GRB 210927B, at 2021-09-27T23:54:45.600 UTC (denoted as T0)ï¼Œ
which was also observed by Fermi/GBM(trigger ID: 654479691)

Its alert data was promptly downlinked to the ground through the short
message service of BeiDou Navigation Satellite System (BDS). The time
latency of the first BeiDou message relative to the trigger time is about
1 minute.

According to the BDS alert data, this burst mainly consists of multiple
pulses with duration of about 120 s. 

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/86486085.60000002energys.png

GECAM-B localized this burst to the following position (J2000): 
Ra: 276.4 deg 
Dec: 76.0 deg
Err: 3.0 deg (1-sigma, statistical only)
The current systematic error of location is estimated to be several degrees 
which could be minimized by the ongoing calibration.

The GECAM preliminary location could be found here: 
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_skymap_bdm_86486085_V01.png

This location is consistent with Fermi/GBM position within the error.

Please note that all GECAM results here are preliminary. The final analysis
will be published in journal papers or GECAM online catalog.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor
(GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in
Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time),
which was funded by the Chinese Academy of Sciences (CAS).


GRB_name: GRB210928A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30912
SUBJECT: GRB 210928A: Fermi-LAT detection
DATE:    21/10/01 14:29:38 GMT
FROM:    Magnus Axelsson at Stockholm U.  <magaxe@kth.se>

M. Axelsson (KTH & Stockholm Univ.), N. Di Lalla (Stanford Univ.), E. Bissaldi (Politecnico & INFN Bari), N. Omodei (Stanford Univ.), C. C. Cheung (NRL) and G. La Mura (LIP) report on behalf of the Fermi-LAT Collaboration:

On September 28th, 2021, Fermi-LAT detected high-energy emission from GRB 210928A, which was also detected by Fermi GBM (trigger 654487236 / 210928084). This source has previously been reported as the Fermi-LAT transient J1623-1752 (Rani et al., ATel #14939) and Swift X-ray transient J162315.0-175233 (Page et al.; ATel #14945). Further analysis shows that the LAT source is consistent with being a GRB, making the Swift transient the afterglow candidate.

The best LAT on-ground location is found to be

RA, Dec = 245.88, -17.91 (degrees, J2000)

with an error radius of 0.15 deg (90% containment, statistical error only). This location is consistent with the Swift X-ray transient.

The position was 16 deg from the LAT boresight at the time of the GBM trigger:

T0 = 02:00:31 UT.

The data from the Fermi-LAT show a significant increase in the event rate after the trigger that is spatially correlated with the GBM emission with high significance. The photon flux above 100 MeV in the time interval 0-1000 s after the trigger is 8.4 (-/+ 1.5) e-06 ph/cm2/s.

The estimated photon index above 100 MeV is -2.2 (-/+ 0.2).

The highest-energy photon is a 6 GeV event which is observed ~50 s after the trigger.

The Fermi-LAT point of contact for this burst is Magnus Axelsson (magaxe@kth.se).

The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.


GRB_name: GRB210928A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30913
SUBJECT: GRB 210928A: Fermi GBM observation
DATE:    21/10/01 15:23:19 GMT
FROM:    Cori Fletcher at USRA  <cfletcher@usra.edu>

C. Fletcher (USRA) and C. Meegan (UAH) report on behalf of the Fermi GBM Team:

"At 02:00:31.01 UT on 28 September 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210928A (trigger 654487236 / 210928084)
which was also detected by the Fermi LAT (M. Axelsson et al. 2021, GCN 30912).
The GBM on-ground location is consistent with the LAT position.

The angle from the Fermi LAT boresight at the GBM trigger time is 16 degrees.

The GBM light curve consists of a multiple peaks
with a duration (T90) of about 24 s (50-300 keV).
The time-averaged spectrum from T0+2.1 s to T0+26.6 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.45 +/- 0.02 and
the cutoff energy, parameterized as Epeak, is 465 +/- 10 keV.

The event fluence (10-1000 keV) in this time interval is
(4.925 +/- 0.052)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+18.04 s in the 10-1000 keV band
is 10.6 +/- 0.3 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"
FSSC: Data  Data Access  GBM<https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/>
GBM Data Products. This page lists the science data products created by the GIOC (GBM Instrument Operations Center) and provided to the FSSC. GBM Daily, Trigger, and Burst Data
fermi.gsfc.nasa.gov


GRB_name: GRB210928A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30914
SUBJECT: GRB 210928A: Swift-XRT refined Analysis
DATE:    21/10/01 17:29:32 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

V. D'Elia (SSDC & INAF-OAR), A. D'Ai (INAF-IASFPA), J.A. Kennea (PSU),
A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), K.L. Page (U.
Leicester), A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester),
A. Melandri (INAF-OAB) and  report on behalf of the Swift-XRT team:
report on behalf of the Swift-XRT team:

We have analysed 5.3 ks of XRT data for the -detected burst GRB
210928A, from 67.4 ks to 262.9 ks after the   trigger. The data are
entirely in Photon Counting (PC) mode. Using 1636 s of PC mode data and
2 UVOT images, we find an enhanced XRT position (using the XRT-UVOT
alignment and matching UVOT field sources to the USNO-B1 catalogue):
RA, Dec = 245.51109, -17.94788 which is equivalent to:

RA (J2000): 16h 22m 02.66s
Dec(J2000): -17d 56' 52.4"

with an uncertainty of 4.4 arcsec (radius, 90% confidence). This
position is 6793.5 arcmin from the  position. 

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.3 (+1.8, -1.3).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.4 (+0.6, -0.3). The
best-fitting absorption column is  2.342 (+3.358, -0.021) x 10^21
cm^-2, consistent with the Galactic value of 2.3 x 10^21 cm^-2
(Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10
keV flux conversion factor deduced from this spectrum  is 4.8 x 10^-11
(5.5 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      2.342 (+3.358, -0.021) x 10^21 cm^-2
Galactic foreground: 2.3 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.4 (+0.6, -0.3)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00014850.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB210928A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30915
SUBJECT: GRB 210928A: Swift-XRT analysis (replaces GCN 30914)
DATE:    21/10/01 17:48:53 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. A. Evans and K.L. Page (U. Leicester) report on behalf of the Swift-XRT team:

GCN Circ (30914) was sent in error, prematurely. The corrected information is below,
and we apologise for the confusion.

We have analysed 5.3 ks of XRT data for the Fermi-detected burst GRB 210928A
(GCN Circs. 30912, 30913). The data were originally collected as a ToO to
observe U Sco, the possible counterpart to the Fermi-LAT source Fermi J1623-1752
(ATEL #14939). While U Sco was not detected, a new transient, Swift
J162315.0-175233 was discovered (ATEL #14945). Further Swift observations were
requested and are ongoing. The discovery of an unannounced Fermi-GBM trigger has
identified this object as GRB 210928A (ATEL #14948), and the manual insertion 
of the already-observed data into the GRB analysis system resulted in the premature
dispatch of this circular.

The Swift-XRT observations at present extend from 67.4 ks to 262.9 ks after the
GBM trigger time. The data are entirely in Photon Counting (PC) mode. Using 1636
s of PC mode data and 2 UVOT images, we find an enhanced XRT position (using the
XRT-UVOT alignment and matching UVOT field sources to the USNO-B1 catalogue):
RA, Dec = 245.51109, -17.94788 which is equivalent to:

RA (J2000): 16h 22m 02.66s
Dec(J2000): -17d 56' 52.4"

with an uncertainty of 4.4 arcsec (radius, 90% confidence). This
position is 29 arcsec from the Fermi-LAT  position. 

The light curve can be modelled with a power-law decay with a decay index of
alpha=1.3 (+1.8, -1.3); however comprising only 3 data points and an upper
limit, this should be viewed with the caution the large error-bars imply.

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.4 (+0.6, -0.3). The
best-fitting absorption column is  2.342 (+3.358, -0.021) x 10^21
cm^-2, consistent with the Galactic value of 2.3 x 10^21 cm^-2
(Willingale et al. 2013). The counts to observed (unabsorbed) 0.3-10
keV flux conversion factor deduced from this spectrum  is 4.8 x 10^-11
(5.5 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      2.342 (+3.358, -0.021) x 10^21 cm^-2
Galactic foreground: 2.3 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.4 (+0.6, -0.3)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00014850.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB210930A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30917
SUBJECT: GRB 210930A: Swift-BAT refined analysis
DATE:    21/10/01 18:22:49 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

H. A. Krimm (NSF), S. D. Barthelmy (GSFC),
V. D'Elia (SSDC & INAF-OAR), S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC),
T. Sakamoto (AGU), M. Stamatikos (OSU)
(i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 210930A (trigger #1075565)
(D'Elia et al., GCN Circ. 30897).  The BAT ground-calculated position is
RA, Dec = 197.415, 48.630 deg which is
   RA(J2000)  =  13h 09m 39.5s
   Dec(J2000) = +48d 37' 47.1"
with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.

The mask-weighted light curve shows a single-pulse structure that
starts at ~T+6 s, peaks at ~T+9 s, and ends at ~T+20 s.
T90 (15-350 keV) is 11.81 +- 1.94 sec (estimated error including
systematics).

The time-averaged spectrum from T+5.84 to T+19.24 sec is best fit
by a simple power-law model.  The power law index of the time-averaged
spectrum is 1.58 +- 0.19.  The fluence in the 15-150 keV band is
4.0 +- 0.5 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from
T+8.40 sec in the 15-150 keV band is 0.7 +- 0.2 ph/cm2/sec.
All the quoted errors are at the 90% confidence level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1075565/BA/


GRB_name: GRB210928A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30918
SUBJECT: GRB 210928A: Kinder SLT-40cm optical limits
DATE:    21/10/01 20:24:10 GMT
FROM:    Ting-Wan Chen at MPE  <janet.chen@astro.su.se>

T.-W. Chen, S. Yang (Stockholm), P. Evans (U. Leicester), W.-J. Hou, C.-S. Lin, Y.-C. Pan, C.-C. Ngeow, H.-Y. Hsiao, and J.-K. Guo (IANCU) report:

We observed the field of the GRB 210928A (Axelsson et al., GCN Circ. 30912), as part of the Kinder survey (Chen et al., AstroNote 2021-92). We used the SLT-40cm at Lulin Observatory, Taiwan, to obtain r-band images.

Observations started at 10:18 UT on 01 of October 2021 (MJD = 59488.430), 3.3 days after the GBM trigger time (Fletcher et al., GCN Circ. 30913), and were centred on the Swift X-ray source J162315.0-175233 (Page et al., ATel #14945), which had been identified as the likely counterpart to the Fermi source (first reported in Rani et al., ATel #14939). The images were combined from 12 frames with 300 sec exposure time for each (two additional frames removed due to poor image quality), taken under a various seeing conditions 2".7 and at an average airmass of 2.4.

We subtracted the template of this field with our combined image, and derived the following preliminary 2.5-sigma limit (in the AB system):
r > 21.22 mag.

Given magnitudes are calibrated against PanSTARRS1 field stars and are not corrected for the expected Galactic foreground extinction corresponding to a reddening of E_(B-V) = 0.29 mag in the direction of the counterpart (Schlafly & Finkbeiner 2011).


GRB_name: GRB210928A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30919
SUBJECT: Correction to GCN 30915: GRB 210928A: Swift-XRT analysis
DATE:    21/10/02 20:01:55 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

K.L. Page (U. Leicester) reports on behalf of the Swift-XRT team:

Incorrect coordinates for the X-ray afterglow of GRB 210928A were
accidentally reported in GCN 30915. The correct position (as earlier
stated in ATel 14945) is:

RA, Dec(J2000) = 245.81275, -17.87598, which is equivalent to

RA(J2000) = 16h 23m 15.06s
Dec(J2000) = -17d 52m 33.5s
with an estimated 90% uncertainty radius of 2.9 arcsec.

The information provided regarding the light-curve and spectrum were for
the afterglow; only the position was incorrect.

We apologise for any confusion.


GRB_name: GRB210928A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30921
SUBJECT: Konus-Wind detection of GRB 210928A
DATE:    21/10/04 12:37:31 GMT
FROM:    Anna Ridnaia at Ioffe Institute  <ridnaia@mail.ioffe.ru>

A. Ridnaia, D. Frederiks, S. Golenetskii, A. Lysenko,
D. Svinkin, A. Tsvetkova,  M. Ulanov, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 210928A
(Fermi-LAT detection: Axelsson et al., GCN 30912;
Fermi-GBM observation: Fletcher & Meegan, GCN 30913)
triggered Konus-Wind at T0=7234.398 s UT (02:00:34.398).

The burst light curve shows a single multi-peaked pulse
started at ~T0-4.3 s with a total duration of ~27.3 s.
The emission is seen up to ~6 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB210928_T07234/

As observed by Konus-Wind, the burst
had a fluence of 6.79(-0.66,+0.71)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+14.416 s,
of 6.45(-1.72,+1.77)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+24.320 s)
is best fit in the 20 keV - 6 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.34(-0.15,+0.16),
the high energy photon index beta = -2.55(-0.35,+0.21),
the peak energy Ep = 361(-33,+38) keV
(chi2 = 61/78 dof).

The spectrum near the maximum count rate
(measured from T0+8.448 to T0+16.128 s)
is best fit in the 20 keV - 6 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.07(-0.21,+0.23),
the high energy photon index beta = -2.73(-0.55,+0.28),
the peak energy Ep = 328(-30,+36) keV
(chi2 = 75/78 dof).

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB210928A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30924
SUBJECT: GRB 210928A: MeerKAT detection 
DATE:    21/10/06 15:55:18 GMT
FROM:    Lauren Rhodes at Oxford  <lauren.rhodes@physics.ox.ac.uk>

L. Rhodes (Oxford/MPIfR), A. van der Horst, S. Chastain (GWU), R. Fender (Oxford/UCT) and E. Tremou (CEA-Saclay) on behalf of the ThunderKAT collaboration.

We observed Fermi J1623-1752 (Atel #14948) as part of the ThunderKAT X-ray binary monitoring program prior to it being reclassified as GRB 210928A. The observation was made as 1.3GHz on 30th September 2021 at 17:07:48UT. The 15-minute observation revealed a point source at the XRT position of GRB 210928A with a peak flux density of 215 +/- 6uJy. The noise in the field is 16uJy.

We thank the staff at the South African Radio Astronomy Observatory for scheduling these observations.


GRB_name: GRB211008A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30926
SUBJECT: GRB 211008A: BALROG localization (Fermi Trigger 655401471 / GRB 211008665)
DATE:    21/10/08 16:24:19 GMT
FROM:    Jochen Greiner at MPE,Garching  <jcg@mpe.mpg.de>

B. Biltzinger, F. Kunzweiler, F. Berlato, J. Burgess & J. Greiner (all MPE Garching) report:

The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
655401471 at 15:57:46 on 08 Oct. 2021 were automatically fitted for spectrum
and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427;
Berlato et al. 2019, ApJ 873, 60).

The best-fit position (1 sigma statistical errors) is:
RA(2000.0) = 296.4+/-0.5 deg
Decl.(2000.0) = 21.7+/-0.4 deg
We estimate an additional systematic error of 2 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB211008665/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB211008665/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB211008665/json

                        


GRB_name: GRB210919A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30934
SUBJECT: GRB 210919A: LDT optical observations and candidate host galaxies
DATE:    21/10/12 23:14:30 GMT
FROM:    Brendan O'Connor at UMD  <oconnorb@umd.edu>

B. O'Connor (UMD, GWU),E. Hammerstein (UMD),S.B. Cenko (UMD,
NASA-GSFC),E. Troja (UMD, NASA-GSFC),A.Gottlieb (UMD,
NASA-GSFC),S.Dichiara (PSU),A. Kutyrev (UMD,NASA-GSFC),
S. Veilleux (UMD)

We observed the field of GRB 210919A (Tohuvavohu et al., GCN 30846)
using the Large Monolithic Imager (LMI) on the 4.3m Lowell Discovery
Telescope (LDT) at Happy Jack, AZ. Observations started on October 11,
2021 at 11:39:44 UT (~3 weeks after the GRB trigger), and were carried
out in r-band for 5x300 s exposures. The observations were performed at
airmass 1.2 with seeing 0.8".

At the position of the optical source reported by Kann et al.
(GCNs 30883 and 30884) we do not detect any source down to a
3-sigma upper limit of r>25.1 AB mag. However, within the XRT
enhanced position (Goad et al., GCN 30850), we detect a source
with magnitude r~24.0+/-0.1 AB mag at position
RA, DEC = 05:21:00.87,+01:18:42.68 +/- 0.5",
which is 3.4" offset from the Kann et al. source (GCNs 30883 and 30884).

The source appears marginally extended although it cannot be
confidently associated with GRB 210919A due to the high probability
of chance coincidence of Pcc=0.45 (Bloom et al. 2002). We also note
the presence of a bright galaxy (also seen in SDSS)
with r~20.47+/-0.05 mag at an offset of ~13" from the XRT localization.
This galaxy has a photometric redshift z~0.27+/-0.12, and probability
of chance coincidence is Pcc=0.15.

Magnitudes are calibrated against the SDSS catalog and are not corrected
for Galactic extinction.

We thank the staff of the Lowell Discovery Telescope for assistance
with these observations.


GRB_name: GRB211019A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30941
SUBJECT: GRB 211019A: Fermi GBM Final Real-time Localization
DATE:    21/10/19 06:09:47 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 05:59:31 UT on 19 Oct 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 211019A (trigger 656315976.19434 / 211019250).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 109.2, Dec = -37.8 (J2000 degrees, equivalent to J2000 07h 16m, -37d 47'), with a statistical uncertainty of 1.0 degrees.

The angle from the Fermi LAT boresight is 64.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211019250/quicklook/glg_skymap_all_bn211019250.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211019250/quicklook/glg_healpix_all_bn211019250.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211019250/quicklook/glg_lc_medres34_bn211019250.gif


GRB_name: GRB211019A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30942
SUBJECT: GRB 211019A: BALROG localization (Fermi Trigger 656315976 / GRB 211019250)
DATE:    21/10/19 06:34:50 GMT
FROM:    Jochen Greiner at MPE,Garching  <jcg@mpe.mpg.de>

F. Kunzweiler, B. Biltzinger, F. Berlato, J. Burgess & J. Greiner (all MPE Garching) report:

The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
656315976 at 05:59:31 on 19 Oct. 2021 were automatically fitted for spectrum
and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427;
Berlato et al. 2019, ApJ 873, 60).

The best-fit position (1 sigma statistical errors) is:
RA(2000.0) = 107.1+/-0.7 deg
Decl.(2000.0) = -38.6+/-0.7 deg
We estimate an additional systematic error of 2 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB211019250/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB211019250/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB211019250/json

                        


GRB_name: GRB211018A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30943
SUBJECT: GRB 211018A: Fermi-LAT detection
DATE:    21/10/19 08:34:58 GMT
FROM:    Magnus Axelsson at Stockholm U.  <magaxe@kth.se>

M. Arimoto (Kanazawa Univ.), M. Axelsson (KTH & Stockholm Univ.), N. Di Lalla (Stanford Univ.), N. Omodei (Stanford Univ.), F. Longo (Univ. and INFN, Trieste) and D. Tak (DESY) report on behalf of the Fermi-LAT Collaboration:

On October 18th, 2021, Fermi-LAT detected high-energy emission from GRB 211018A, which was also detected by Fermi GBM (trigger 656288898 / 211018936). The best LAT on-ground location is found to be

RA, Dec = 19.68, -3.60 (degrees, J2000)

with an error radius of 0.19 deg (90% containment, statistical error only).

The position was 68 deg from the LAT boresight at the time of the GBM trigger:

T0 = 22:28:13.9 UT.

The data from the Fermi-LAT show a significant increase in the event rate after the trigger that is temporally and spatially correlated with the GBM emission with high significance. The photon flux above 100 MeV in the time interval 0-300 s after the trigger is 1.2 (-/+ 0.3) e-04 ph/cm2/s.

The estimated photon index above 100 MeV is -2.0 (-/+ 0.2).

The highest-energy photon is a 3.3 GeV event which is observed 25 seconds after the GBM trigger.

A Swift ToO has been requested for this burst.

The Fermi-LAT point of contact for this burst is Donggeun Tak (takdg123@gmail.com).

The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.


GRB_name: GRB211019A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30944
SUBJECT: Fermi GRB 211019A: Global MASTER-Net observations report 
DATE:    21/10/19 11:00:22 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev, O.Ershova 
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

V. Yurkov, A. Gabovich, Yu. Sergienko 
(Blagoveschensk Educational State University)




MASTER-IAC robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Spain (IAC Teide Observatory) started inspect of the Fermi GRB 211019A ( Fermi GBM team, GCN 30941) errorbox  91 sec after notice time and 130 sec after trigger time at 2021-10-19 06:01:42 UT, with upper limit up to  17.3 mag. Observations started at twilight.  The observations began at zenith distance = 66 deg. The sun  altitude  is -14.8 deg. 

MASTER-OAFA robotic telescope  located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 211019A errorbox  10590 sec after notice time and 10629 sec after trigger time at 2021-10-19 08:56:41 UT, with upper limit up to  17.6 mag. Observations started at twilight.  The observations began at zenith distance = 14 deg. The sun  altitude  is -12.1 deg. 

The galactic latitude b = -12 deg., longitude l = 251 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1756842

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

     146 | 2021-10-19 06:01:42 |          MASTER-IAC | (07h 17m 09.18s , -37d 56m 16.1s) |  P| |    30 | 13.8 |        
     186 | 2021-10-19 06:01:42 |          MASTER-IAC | (07h 17m 09.18s , -37d 56m 16.1s) |  P| |   110 | 14.7 |  Coadd 
     146 | 2021-10-19 06:01:42 |          MASTER-IAC | (07h 16m 10.91s , -37d 50m 38.7s) |  P- |    30 | 13.5 |        
     186 | 2021-10-19 06:01:42 |          MASTER-IAC | (07h 16m 10.91s , -37d 50m 38.7s) |  P- |   110 | 14.6 |  Coadd 
     197 | 2021-10-19 06:02:33 |          MASTER-IAC | (07h 17m 04.65s , -37d 56m 56.7s) |  P| |    30 | 13.9 |        
     197 | 2021-10-19 06:02:33 |          MASTER-IAC | (07h 16m 06.36s , -37d 51m 18.8s) |  P- |    30 | 13.9 |        
     257 | 2021-10-19 06:03:23 |          MASTER-IAC | (07h 17m 04.32s , -37d 55m 58.0s) |  P| |    50 | 14.5 |        
     257 | 2021-10-19 06:03:23 |          MASTER-IAC | (07h 16m 06.03s , -37d 50m 20.6s) |  P- |    50 | 14.4 |        
     334 | 2021-10-19 06:04:34 |          MASTER-IAC | (07h 17m 09.19s , -37d 56m 59.7s) |  P| |    60 | 16.0 |        
     424 | 2021-10-19 06:04:34 |          MASTER-IAC | (07h 17m 09.20s , -37d 56m 59.7s) |  P| |   240 | 17.3 |  Coadd 
     334 | 2021-10-19 06:04:34 |          MASTER-IAC | (07h 16m 10.90s , -37d 51m 23.7s) |  P- |    60 | 15.7 |        
     424 | 2021-10-19 06:04:34 |          MASTER-IAC | (07h 16m 10.90s , -37d 51m 23.7s) |  P- |   240 | 17.1 |  Coadd 
     424 | 2021-10-19 06:05:55 |          MASTER-IAC | (07h 17m 04.40s , -37d 58m 01.9s) |  P| |    80 | 16.6 |        
     424 | 2021-10-19 06:05:55 |          MASTER-IAC | (07h 16m 06.17s , -37d 52m 25.3s) |  P- |    80 | 16.4 |        
     535 | 2021-10-19 06:07:35 |          MASTER-IAC | (07h 17m 10.22s , -37d 58m 01.5s) |  P| |   100 | 17.1 |        
     535 | 2021-10-19 06:07:35 |          MASTER-IAC | (07h 16m 12.08s , -37d 52m 25.3s) |  P- |   100 | 16.9 |        
     665 | 2021-10-19 06:09:36 |          MASTER-IAC | (07h 17m 07.05s , -37d 56m 23.7s) |  P| |   120 | 17.3 |        
     665 | 2021-10-19 06:09:36 |          MASTER-IAC | (07h 16m 08.99s , -37d 50m 47.4s) |  P- |   120 | 17.1 |        
   10660 | 2021-10-19 08:56:41 |         MASTER-OAFA | (07h 10m 41.71s , -39d 22m 20.0s) |   C |    60 | 17.6 |        
   10903 | 2021-10-19 09:00:43 |         MASTER-OAFA | (07h 08m 39.36s , -37d 27m 29.3s) |   C |    60 | 17.5 |        
   10983 | 2021-10-19 09:02:04 |         MASTER-OAFA | (07h 18m 38.70s , -37d 26m 09.7s) |   C |    60 | 17.3 |        
   11381 | 2021-10-19 09:08:42 |         MASTER-OAFA | (07h 12m 16.15s , -41d 14m 31.8s) |   C |    60 | 16.7 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB211018A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30945
SUBJECT: GRB 211018A: Detection by GRBAlpha
DATE:    21/10/19 12:05:37 GMT
FROM:    Masanori Ohno at Hiroshima U  <ohno@astro.hiroshima-u.ac.jp>

M. Ohno (Eotvos U./Konkoly Observatory/Hiroshima U.),  J. Ripa (Masaryk
U.), H. Takahashi (Hiroshima U.), A. Pal, L. Meszaros, B. Csak (Konkoly
Observatory), N. Werner, M. Topinka, F. Munz, F. Hroch (Masaryk U.), T.
Urbanec, M. Kasal,  A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus,
M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M.
Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner
Research Center/Eotvos U.), Yuusuke Uchida, Helen Poon, H. Matake, N.
Uchida (Hiroshima U.), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), T.
Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa,
K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.),
K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno
(Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J.
Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.) -- the GRBAlpha
collaboration.

The bright/long duration GRB 211018A (Fermi-GBM detection trigger
656288898/211018936, Fermi-LAT detection; Arimoto et al., GCN Circ. 30943)
was detected by the GRBAlpha 1U CubeSat (Pal et al. Proc. SPIE 2020).

The light curve shows a very long multiple-peaked structure with a duration
of about 168 s (T90 = 140 s). At 22:29:34 UTC, our detection reached a SNR
~ 46.

The light curve obtained by GRBAlpha is available here:
https://grbalpha.konkoly.hu/static/share/GRB211018A_GCN.pdf

GRBAlpha is a demonstration mission for a future CubeSats constellation
(Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75
x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy
range from ~50 keV to ~1000 keV. GRBAlpha was launched on 2021 March 22
from Baikonur. After its commissioning phase, the scientific observations
are now under way. To increase the duty cycle and the downlink rate, the
upgrade of the on-board data acquisition software stack is in progress. The
ground segment is also supported by the radio amateur community and it
takes advantage of the SatNOGS network for increased data downlink volume.


GRB_name: GRB211019A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30946
SUBJECT: GRB 211019A: Detection by GRBAlpha
DATE:    21/10/19 15:11:53 GMT
FROM:    Masanori Ohno at Hiroshima U  <ohno@astro.hiroshima-u.ac.jp>

 J. Ripa (Masaryk U.), M. Ohno (Eotvos U./Konkoly Observatory/Hiroshima
U.), H. Takahashi (Hiroshima U.), A. Pal, L. Meszaros, B. Csak (Konkoly
Observatory), N. Werner, M. Topinka, F. Munz, F. Hroch (Masaryk U.), T.
Urbanec, M. Kasal,  A. Povalac (Brno U. of Technology), J. Hudec, J. Kapus,
M. Frajt (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), M.
Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), G. Galgoczi (Wigner
Research Center/Eotvos U.), Yuusuke Uchida, Helen Poon, H. Matake, N.
Uchida (Hiroshima U.), T. Bozoki (Eotvos U.), G. Dalya (Eotvos U.), T.
Enoto (Kyoto U.), Zs. Frei (Eotvos U.), G. Friss (Eotvos U.), Y. Fukazawa,
K. Hirose (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.),
K. Kapas (Eotvos U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno
(Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), J.
Takatsy (Eotvos U.), K. Torigoe (Hiroshima U.) -- the GRBAlpha
collaboration.

The bright/long duration GRB 211019A (Fermi-GBM detection;  GCN Circ.
30941, BALROG localization; Kunzweiler et al., GCN 30942) was detected by
the GRBAlpha 1U CubeSat (Pal et al. Proc. SPIE 2020).

The light curve shows a strong FRED-like structure with the duration of
about 40 s (T90 = 36 s). At 05:59:34 UTC, our detection reached a peak SNR
~ 39.

The light curve obtained by GRBAlpha is available here:
https://grbalpha.konkoly.hu/static/share/GRB211019A_GCN.pdf

GRBAlpha is a demonstration mission for a future CubeSats constellation
(Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75
x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy
range from ~50 keV to ~1000 keV. GRBAlpha was launched on 2021 March 22
from Baikonur. After its commissioning phase, the scientific observations
are now under way. To increase the duty cycle and the downlink rate, the
upgrade of the on-board data acquisition software stack is in progress. The
ground segment is also supported by the radio amateur community and it
takes advantage of the SatNOGS network for increased data downlink volume.


GRB_name: GRB211018A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30947
SUBJECT: GRB 211018A: Fermi GBM observation
DATE:    21/10/19 17:18:39 GMT
FROM:    Oliver J Roberts at USRA/NASA  <oliver.roberts@nasa.gov>

 O.J Roberts (USRA/NASA-MSFC) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 22:28:13.94 UT on 18 October 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 211018A (trigger 656288898 / 211018936),
which was also detected by the Fermi LAT (M. Axelsson et al. 2021, GCN 30943),
and GRBAlpha (M. Ohno, GCN 30945). The GBM on-ground location is consistent
with the Fermi-LAT position.

The angle from the Fermi LAT boresight at the GBM trigger time is 68 degrees.

The GBM light curve consists of multiple peaks
with a duration (T90) of 123.9 s (50-300 keV).
The time-averaged spectrum from T-2.4s to T0+142.0 s is
well fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.75 +/- 0.01 and
the cutoff energy, parameterized as Epeak, is 351.4 +/- 4.9 keV.

The Band function also fits the burst equally well, with parameters,
alpha= -0.74 +/- 0.01, beta= -3.13 +/- 0.28 and Epeak of 344.6 +/- 6.2 keV.

The event fluence (10-1000 keV) in the T90 interval is
(1.53347 +/- 0.0003)E-04 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+134.5 s in the 10-1000 keV band
is 15.6 +/- 0.3 ph/s/cm^2.

We note that owing to the large total fluence of this burst,
the 1-sec peak photon flux begins after the T90.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB190530A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30949
SUBJECT: BepiColombo MGNS joins the IPN
DATE:    21/10/20 12:08:08 GMT
FROM:    Kevin Hurley at UCBerkeley/SSL  <kevin.hurley@comcast.net>

K. Hurley on behalf of the IPN team,

A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin 
on behalf of the MGNS/BepiColombo team, and

J. Benkhoff on behalf of the BepiColombo team, report:

The ESA/JAXA BepiColombo mission was launched on October 20, 2018 on a 
7.2-year journey to Mercury. After arrival in late 2025, the mission 
will spend a nominal one year in Mercury orbit. The mission consists of 
two spacecraft: the JAXA-provided Mio spacecraft for the thorough 
exploration of the environment, and the ESA-led Mercury Planetary 
Orbiter, MPO, for a comprehensive exploration of the planet itself, the 
interior, and its magnetic field. The MPO contains the Mercury Gamma-Ray 
and Neutron Spectrometer (MGNS) experiment [1, 2] consisting of a 3â€ 
diameter x 3â€ long CeBr3 scintillator, which also has a gamma-ray burst 
detection capability. During the cruise phase so far, MGNS operated for 
about 23 months, and has detected 38 confirmed gamma-ray bursts, 21 of 
which have been localized to annuli using data from HEND/Mars Odyssey, 
which is also part of the IPN since 2002. The verification of the 
localization accuracy of this method was based on gamma-ray bursts for 
which optical afterglows were detected. Reference [3] presents 5 
gamma-ray bursts as examples of these localizations.

MGNS is now the 34th experiment to be integrated into the interplanetary 
network (IPN) since 1977, which currently consists of Konus-Wind, Mars 
Odyssey, BepiColombo, Swift, INTEGRAL and AGILE. In this configuration, 
the IPN now has two interplanetary spacecraft, which will lead to more 
precise GRB localizations.

References:

1. Mitrofanov, I.G., Kozyrev, A.S., Lisov, D.I., Litvak, M. L., et al. 
(2021). Space Science Reviews. Volume 217, Issue 5, article id.67A.

2. https://np.cosmos.ru/index.php/en-us/instruments/mgns

3. The links below show maps with localization annuli from MGNS-HEND 
data for 5 gamma-ray bursts: GRB 190530A, GRB 200219C, GRB 200415A, GRB 
200716C and GRB 210112A.

http://l503.iki.rssi.ru/owncloud/index.php/s/bXsgMFb9afifHzz

http://l503.iki.rssi.ru/owncloud/index.php/s/mPC5lrPy2pYLmbz

http://l503.iki.rssi.ru/owncloud/index.php/s/FcbgOtcA5pEx3nD

http://l503.iki.rssi.ru/owncloud/index.php/s/58JCvMJ6x5uzbbU

http://l503.iki.rssi.ru/owncloud/index.php/s/g4miSw176EHU7bL


GRB_name: GRB211021A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30952
SUBJECT: GRB 211021A: BALROG localization (Fermi Trigger 656506979 / GRB 211021460)
DATE:    21/10/21 12:02:57 GMT
FROM:    Jochen Greiner at MPE,Garching  <jcg@mpe.mpg.de>

B. Biltzinger, F. Kunzweiler, F. Berlato, J. Burgess & J. Greiner (all MPE Garching) report:

The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
656506979 at 11:02:54 on 21 Oct. 2021 were automatically fitted for spectrum
and sky location with BALROG (Burgess et al. 2018, MNRAS 476, 1427;
Berlato et al. 2019, ApJ 873, 60).

The best-fit position (1 sigma statistical errors) is:
RA(2000.0) = 29.4+/-3.2 deg
Decl.(2000.0) = 27.2+/-2.1 deg
We estimate an additional systematic error of 1 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB211021460/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB211021460/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB211021460/json

                        


GRB_name: GRB211018A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30953
SUBJECT: GRB 211018A: Swift ToO observations
DATE:    21/10/21 14:26:20 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a ToO observation of the Fermi/LAT GRB 211018A. 
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021463

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Fermi/LAT event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a 
GCN Circular after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB211022A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30955
SUBJECT: GRB 211022A: GECAM detection
DATE:    21/10/22 14:11:29 GMT
FROM:    Zhao Yi at POLAR  <yizhao@ihep.ac.cn>

Yi Zhao, S. L. Xiong, S. Xiao, C. Cai, J. J. He, Y. Huang, Z. W. Guo, 
C. Y. Li, X. B. Li, J. C. Liu, X. Y. Song, C. W. Wang, P. Wang, S. L. Xie, W. C. Xue,
Q. B. Yi, Y. Q. Zhang, G. Y. Zhao, X. Y. Zhao, C. Zheng, Y. Q. Du, D. Y. Guo, 
J. Liang, F. J. Lu, Q. Luo, X. Ma, W. X. Peng, R. Qiao, L. M. Song, J. Wang, H. Wu, 
P. Zhang, S. N. Zhang, X. L. Zhang, Z. Zhang, S. J. Zheng (IHEP),
report on behalf of GECAM team:

During the commissioning phase, GECAM-B was triggered in-flight by a
burst, GRB 211022A, at 2021-10-22T00:47:28.100 UTC (denoted as T0),
which was also observed by KONUS/WIND.

Its alert data was promptly downlinked to the ground through the short
message service of BeiDou Navigation Satellite System (BDS). The time
latency of the first BeiDou message relative to the trigger time is about
1 minute.

According to the BDS alert data, this burst mainly consists of multiple
pulses with duration of about 120 s.

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_lc_grd_all_combine_88562848.png

GECAM-B localized this burst to the following position (J2000): 
Ra: 164.5 deg 
Dec: -50.6 deg
Err: 2.0 deg (1-sigma, statistical only)
The current systematic error of location is estimated to be several degrees 
which could be minimized by the ongoing calibration.

The GECAM preliminary location could be found here: 
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_skymap_bdm_88562848_V01.png

Please note that all GECAM results here are preliminary. The final analysis
will be published in journal papers or GECAM online catalog.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor
(GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in
Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time),
which was funded by the Chinese Academy of Sciences (CAS).


GRB_name: GRB210927B
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30956
SUBJECT: IPN Triangulation of GRB 210927B
DATE:    21/10/22 20:49:00 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the MGNS/BepiColombo and HEND/Mars Odyssey teams,

J. Benkhoff on behalf of the BepiColombo team,

K. Hurley, on behalf of the IPN,

D. Svinkin, S. Golenetskii, D. Frederiks, A. Ridnaia,
A. Lysenko, and T. Cline on behalf of the Konus-Wind team,

A. Goldstein, M. S. Briggs, and C. Wilson-Hodge
on behalf of the Fermi GBM team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu
on behalf of the Swift-BAT team, and

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:

The long-duration GRB 210927B (GECAM-B detection: GCN circ. 30910)
was detected by BepiColombo (MGNS), in the vicinity of Mercury
(see introductory GCN Circ. 30949); Mars-Odyssey (HEND);
GECAM-B; Fermi (GBM trigger 654479691); Konus-Wind; INTEGRAL (SPI-ACS);
and Swift (BAT) at about 86086 s UT (23:54:46).
The burst was outside the coded field of view of the BAT.

The burst light curves in the energy range 30 keV-1.5 MeV (HEND)
and 250-450 keV (MGNS) exhibit a multi-peaked pulse structure
with a total duration of ~25 s.

We have triangulated GRB 210927B to the following 3 sigma annuli:
---------------------------------------------------------
          R.A.(J2000)  Dec.(J2000)    R      +dR     -dR
                deg      deg         deg     deg     deg
---------------------------------------------------------
MGNS-HEND     2.101    -1.674      94.136  +0.034 -0.079
Konus-HEND  187.856    -2.595      88.396  +0.017 -0.017
Konus-GBM   161.442     7.403      85.952  +0.562 -0.562
---------------------------------------------------------

The MGNS-HEND and Konus-HEND annuli intersect to form two error
boxes one of which is inconsistent with the Konus-GBM annulus,
the KW ecliptic latitude response, and the Fermi (GBM) final position.

The correct preliminary, 3 sigma error box is:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   263.021 (17h 32m 05s) +73.775 (+73d 46' 32")
  Corners:
   263.554 (17h 34m 13s) +73.267 (+73d 15' 59")
   262.667 (17h 30m 40s) +74.201 (+74d 12' 03")
   262.825 (17h 31m 18s) +73.913 (+73d 54' 45")
   263.687 (17h 34m 45s) +72.979 (+72d 58' 46")
  ---------------------------------------------
The error box area is 49 sq. arcmin, and its maximum
dimension is 1.26 deg (the minimum one is 2.0 arcmin).
The Sun distance was 89 deg.

This box may be improved.

A triangulation map is posted at:
http://l503.iki.rssi.ru/owncloud/index.php/s/nFbsu69DWdxQvd2


GRB_name: GRB211023A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30958
SUBJECT: GRB 211023A: Fermi GBM Final Real-time Localization
DATE:    21/10/23 13:16:10 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 13:05:43 UT on 23 Oct 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 211023A (trigger 656687148.17411 / 211023546).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 78.8, Dec = 82.3 (J2000 degrees, equivalent to J2000 05h 15m, 82d 17'), with a statistical uncertainty of 1.0 degrees.

The angle from the Fermi LAT boresight is 56.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211023546/quicklook/glg_skymap_all_bn211023546.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211023546/quicklook/glg_healpix_all_bn211023546.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211023546/quicklook/glg_lc_medres34_bn211023546.gif


GRB_name: GRB211023B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30960
SUBJECT: GRB 211023B: Swift detection of a possibly short burst with an optical counterpart
DATE:    21/10/23 21:16:59 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

S. Dichiara (NASA/GSFC/UMCP), J.D. Gropp (PSU), J. A. Kennea (PSU),
H. A. Krimm (NSF), N. P. M. Kuin (UCL-MSSL), A. Y. Lien (U Tampa),
F. E. Marshall (NASA/GSFC), A. Melandri (INAF-OAB),
D. M. Palmer (LANL), B. Sbarufatti (PSU), M. H. Siegel (PSU) and
A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 21:05:52 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 211023B (trigger=1080859).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 170.302, +39.137 which is 
   RA(J2000) = 11h 21m 12s
   Dec(J2000) = +39d 08' 14"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 2 sec.  The peak count rate
was ~1500 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 21:07:27.3 UT, 95.3 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 170.31048, 39.13595 which is equivalent
to:
   RA(J2000)  = 11h 21m 14.52s
   Dec(J2000) = +39d 08' 09.4"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 23 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at https://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (2.30 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 3.5
(+2.51/-2.21) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 97 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  = 11:21:14.31 = 170.30963
  DEC(J2000) = +39:08:08.8  =  39.13578
with a 90%-confidence error radius of about 0.79 arc sec. This position is 3.2
arc sec. from the center of the XRT error circle. The estimated magnitude is
19.32 with a 1-sigma error of about  0.16. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.024. 

We note that this is Swift's 1500th GRB. 

Burst Advocate for this burst is S. Dichiara (dichiara AT umd.edu). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)


GRB_name: GRB211023A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30961
SUBJECT: GRB 211023A: Fermi-LAT detection
DATE:    21/10/23 22:25:44 GMT
FROM:    Niccolo Di Lalla at Stanford U  <niccolo.dilalla@stanford.edu>

N. Di Lalla (Stanford Univ.), F. Longo (Univ. and INFN, Trieste) and M. Ohno (Hiroshima Univ. & Eotvos Univ) report on behalf of the Fermi-LAT Collaboration:


On October 23rd, 2021, Fermi-LAT detected high-energy emission from GRB 211023A, which was also detected by Fermi GBM (trigger 656687148 / 211023546, GCN 30958). The best LAT on-ground location is found to be:


RA, Dec = 72.3, 85.3 (degrees, J2000)


with an error radius of 0.1 deg (90% containment, statistical error only).


The position was 54 deg from the LAT boresight at the time of the GBM trigger:


T0 = 13:05:43 UT.


The data from the Fermi-LAT show a significant increase in the event rate after the trigger that is temporally and spatially correlated with the GBM emission with high significance. The photon flux above 100 MeV in the time interval 0-2500 s after the trigger is 3.4 (-/+ 0.6) e-06 ph/cm2/s.


The estimated photon index above 100 MeV is -1.8  (-/+ 0.1).


The highest-energy photon is a 8.6 GeV event which is observed at 1832 seconds after the GBM trigger.


A Swift ToO has been requested for this burst.


The Fermi-LAT point of contact for this burst is Donggeun Tak (takdg123@gmail.com<mailto:takdg123@gmail.com>).


The Fermi-LAT is a pair conversion telescope designed to cover the energy band from 20 MeV to greater than 300 GeV. It is the product of an international collaboration between NASA and DOE in the U.S. and many scientific institutions across France, Italy, Japan and Sweden.


GRB_name: GRB211024A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30962
SUBJECT: GRB 211024A: Fermi GBM Final Real-time Localization
DATE:    21/10/24 01:44:24 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely SHORT GRB

At 01:34:11 UT on 24 Oct 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 211024A (trigger 656732056.398738 / 211024065).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 358.1, Dec = 3.1 (J2000 degrees, equivalent to J2000 23h 52m, 3d 06'), with a statistical uncertainty of 16.9 degrees.

The angle from the Fermi LAT boresight is 88.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211024065/quicklook/glg_skymap_all_bn211024065.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211024065/quicklook/glg_healpix_all_bn211024065.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211024065/quicklook/glg_lc_medres34_bn211024065.gif


GRB_name: GRB211024A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30963
SUBJECT: Fermi GRB 211024A: Global MASTER-Net observations report 
DATE:    21/10/24 02:30:28 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev, O.Ershova 
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

V. Yurkov, A. Gabovich, Yu. Sergienko 
(Blagoveschensk Educational State University)




MASTER-OAFA robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 211024A ( Fermi GBM team, GCN 30962) errorbox  280 sec after notice time and 309 sec after trigger time at 2021-10-24 01:39:20 UT, with upper limit up to  19.1 mag. The observations began at zenith distance = 47 deg. The sun  altitude  is -32.7 deg. 

The galactic latitude b = -57 deg., longitude l = 97 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1763191

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

     339 | 2021-10-24 01:39:20 |         MASTER-OAFA | (00h 38m 42.05s , +11d 16m 19.3s) |   C |    60 | 19.0 |        
     419 | 2021-10-24 01:40:40 |         MASTER-OAFA | (00h 46m 53.72s , +11d 18m 21.4s) |   C |    60 | 19.1 |        
     501 | 2021-10-24 01:42:02 |         MASTER-OAFA | (00h 38m 55.48s , +13d 12m 22.8s) |   C |    60 | 18.9 |        
     580 | 2021-10-24 01:43:21 |         MASTER-OAFA | (00h 47m 13.18s , +13d 11m 29.3s) |   C |    60 | 18.9 |        
     660 | 2021-10-24 01:44:41 |         MASTER-OAFA | (00h 38m 29.82s , +09d 22m 30.1s) |   C |    60 | 19.0 |        
     739 | 2021-10-24 01:46:00 |         MASTER-OAFA | (00h 46m 33.62s , +09d 24m 18.1s) |   C |    60 | 19.0 |        
     819 | 2021-10-24 01:47:20 |         MASTER-OAFA | (00h 54m 36.41s , +13d 12m 38.5s) |   C |    60 | 18.8 |        
     978 | 2021-10-24 01:49:59 |         MASTER-OAFA | (00h 54m 12.45s , +11d 17m 40.6s) |   C |    60 | 18.7 |        
    1139 | 2021-10-24 01:52:40 |         MASTER-OAFA | (00h 53m 50.67s , +09d 24m 40.5s) |   C |    60 | 18.6 |        
    1634 | 2021-10-24 02:00:55 |         MASTER-OAFA | (01h 01m 52.87s , +09d 23m 31.2s) |   C |    60 | 18.6 |        
    1714 | 2021-10-24 02:02:15 |         MASTER-OAFA | (00h 38m 36.81s , +11d 18m 11.9s) |   C |    60 | 18.8 |        
    1795 | 2021-10-24 02:03:36 |         MASTER-OAFA | (00h 46m 51.74s , +11d 17m 19.2s) |   C |    60 | 18.8 |        
    1874 | 2021-10-24 02:04:55 |         MASTER-OAFA | (00h 38m 53.73s , +13d 10m 13.7s) |   C |    60 | 18.6 |        
    1956 | 2021-10-24 02:06:17 |         MASTER-OAFA | (00h 47m 13.27s , +13d 10m 47.5s) |   C |    60 | 18.7 |        
    2036 | 2021-10-24 02:07:37 |         MASTER-OAFA | (00h 38m 26.10s , +09d 23m 54.7s) |   C |    60 | 18.8 |        
    2116 | 2021-10-24 02:08:57 |         MASTER-OAFA | (00h 46m 32.07s , +09d 22m 41.4s) |   C |    60 | 18.7 |        
    2196 | 2021-10-24 02:10:17 |         MASTER-OAFA | (00h 54m 34.50s , +13d 12m 15.5s) |   C |    60 | 18.6 |        
    2358 | 2021-10-24 02:12:59 |         MASTER-OAFA | (00h 54m 06.34s , +11d 18m 29.1s) |   C |    60 | 18.4 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB211023B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30964
SUBJECT: Swift GRB 211023B: Global MASTER-Net observations report 
DATE:    21/10/24 03:28:29 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev, O.Ershova 
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

V. Yurkov, A. Gabovich, Yu. Sergienko 
(Blagoveschensk Educational State University)




MASTER-Kislovodsk robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB 211023B ( S. Dichiara et al., GCN 30960) errorbox  631 sec after notice time and 655 sec after trigger time at 2021-10-23 21:16:47 UT, with upper limit up to  15.2 mag. The observations began at zenith distance = 89 deg. The sun  altitude  is -58.3 deg. 

The galactic latitude b = 68 deg., longitude l = 175 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1762968

We obtain a following upper limits.  

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

     721 |   MASTER-Kislovodsk |  P- |   130 | 14.5 |        
     874 |   MASTER-Kislovodsk |  P- |   160 | 14.9 |        
    1252 |   MASTER-Kislovodsk |  P- |   180 | 15.2 |        


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB211023A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30965
SUBJECT: GRB 211023A: Fermi GBM detection
DATE:    21/10/24 05:04:53 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076@uah.edu>

S. Lesage (UAH), S. Poolakkil (UAH) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 13:05:43 UT on 23 October 2021, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 211023A (trigger 656687148/211023546)
which was also detected by Fermi-LAT (N. Di Lalla et al. 2021, GCN 30961).
The Fermi GBM Final Real-time Localization (GCN 30958) is consistent with
the Fermi-LAT position.

The angle from the Fermi LAT boresight is 53 degrees.

The GBM light curve consists of two emission episodes with a duration (T90)
of about 80 s (10-1000 keV). The time-averaged spectrum
from T0+53 to T0+158 s is best fit by
a Band function with Epeak = 92 +/- 2 keV,
alpha = -1.74 +/- 0.01, and beta = -2.55 +/- 0.07.

The event fluence (10-1000 keV) in this time interval is
(1.114 +/- 0.007)E-08 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+72.1 s in the 10-1000 keV band is 27.4 +/- 0.7 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support
Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB211023B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30966
SUBJECT: GRB 211023B: Enhanced Swift-XRT position
DATE:    21/10/24 06:44:14 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A.P. Beardmore, P.A. Evans, M.R. Goad and J.P. Osborne (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 3338 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 211023B, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 170.30871, +39.13534 which is equivalent
to:

RA (J2000): 11h 21m 14.09s
Dec (J2000): +39d 08' 07.2"

with an uncertainty of 2.7 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB211023B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30967
SUBJECT: GRB 211023B: Swift-XRT refined Analysis
DATE:    21/10/24 07:38:10 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A.P. Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne
(U. Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi (INAF-IASFPA) ,
M. Capalbi (INAF-IASFPA), D.N. Burrows (PSU), J. D. Gropp (PSU), J.A.
Kennea (PSU) and S. Dichiara report on behalf of the Swift-XRT team:

We have analysed 6.3 ks of XRT data for GRB 211023B (Dichiara et al.
GCN Circ. 30960), from 79 s to 24.8 ks after the  BAT trigger. The data
comprise 8 s in Windowed Timing (WT) mode (taken while Swift was
slewing), with the remainder in Photon Counting (PC) mode. The enhanced
XRT position for this burst was given by Beardmore et al. (GCN Circ.
30966).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.03 (+0.12, -0.10).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.08 (+0.24, -0.22). The
best-fitting absorption column is  9.8 (+6.0, -5.1) x 10^20 cm^-2, in
excess of the Galactic value of 2.3 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.2 x 10^-11 (4.0 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      9.8 (+6.0, -5.1) x 10^20 cm^-2
Galactic foreground: 2.3 x 10^20 cm^-2
Excess significance: 2.4 sigma
Photon index:      2.08 (+0.24, -0.22)

If the light curve continues to decay with a power-law decay index of
1.03, the count rate at T+24 hours will be 1.5 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.7 x
10^-14 (5.9 x 10^-14) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01080859.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB211022A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30968
SUBJECT: GRB 211022A: AstroSat CZTI detection
DATE:    21/10/24 07:45:11 GMT
FROM:    Gaurav Waratkar at IIT,Bombay  <gauravwaratkar@iitb.ac.in>

V. Prasad (IUCAA), P. Sawant (IUCAA), G. Waratkar (IITB), A. Vibhute
(IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao
(IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat
CZTI collaboration:

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al.,
2021, JApA, 42, 73) showed detection of a long GRB 211022A, which was
also detected by GECAM (Zhao et al., GCN 30955).

The source was clearly detected in the 20-200 keV energy range. The
light curve showed multiple peaks of emission with the strongest peak at
2021-10-22 00:48:52.0 UT. The measured peak count rate associated with
the burst is 166 (+14, -13) cts/s above the background in the combined
data of four quadrants, with a total of 11186 (+925, -981) cts. The
local mean background count rate was 598 (+1, -1) cts/s. Using
cumulative rates, we measure a T90 of 92 (+63, -9) s.

It was also clearly detected in the CsI anticoincidence (Veto) detector
in the 100-500 keV energy range. The light curve showed multiple peaks
of emission with the strongest peak at 2021-10-22 00:48:54.1 UT. The
measured peak count rate is 2130 (+71, -86) cts/s above the background
in the combined Veto data of four quadrants, with a total of 159488
(+3241, -5602) cts. The local mean background count rate was 21425 (+3,
-91) cts/s. We measure a T90 of 119 (+5, -10) s from the cumulative Veto
light curve.

CZTI GRB detections are reported regularly on the payload site at
http://astrosat.iucaa.in/czti/?q=grb [1]. CZTI is built by a TIFR-led
consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC,
and PRL. The Indian Space Research Organisation funded, managed and
facilitated the project.
 

Links:
------
[1] http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB211023A
Detection_method: Fermi LAT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30969
SUBJECT: GRB 211023A: AGILE detection
DATE:    21/10/24 09:42:45 GMT
FROM:    Alessandro Ursi at INAF/IAPS  <alessandro.ursi@gmail.com>

A. Ursi, M. Cardillo (INAF/IAPS), M. Tavani (INAF/IAPS, and Univ. Roma Tor
Vergata), A. Argan, C. Casentini, Y. Evangelista, E. Menegoni, L. Foffano,
G. Piano (INAF/IAPS), F. Lucarelli, C. Pittori, F. Verrecchia (SSDC, and
INAF/OAR), A. Bulgarelli, A. Di Piano, V. Fioretti, F. Fuschino, N.
Parmiggiani (INAF/OAS-Bologna), M. Marisaldi (INAF/OAS-Bologna, and Bergen
University), M. Pilia, A. Trois (INAF/OA-Cagliari), I. Donnarumma (ASI), F.
Longo (Univ. Trieste and INFN Trieste), A. Giuliani (INAF/IASF-Mi), report
on behalf of the AGILE Team:

The AGILE satellite detected the long GRB 211023A at T0 = 2021-10-23
13:07:58 s (UTC), reported by Fermi GBM (GCNs #30958, #30965) and Fermi LAT
(GCN #30961).

The burst is clearly visible in the AGILE scientific ratemeters of the
SuperAGILE (SA; 20-60 keV), MiniCALorimeter (MCAL; 0.4-100 MeV), and
AntiCoincidence (AC; 50-200 keV) detectors. The event lasted about 45 s and
it released a total number of 5300 counts in the SA detector (above a
background rate of 90 Hz), 64325 counts in the MCAL detector (above a
background rate of 1200 Hz), and 233020 counts in the AC detector (above a
background rate of 2810 Hz). The AGILE ratemeter light curves can be found
at http://www.agilescienceapp.it/notices/GRB211023A_AGILE_RM.png .

The event also triggered a partial high time resolution MCAL data
acquisition, from T1 = 2021-10-23 13:07:32.91 s +/- 0.01 (UTC) to T2 =
2021-10-23 13:08:05.20 +/- 0.01 s (UTC), and released 12480 counts in the
detector, above a background rate of 620 Hz. The time-integrated spectrum
of the first 17 s of the burst can be fitted in the energy range 0.4-50 MeV
with a single power-law with ph. ind. = -2.45 (-0.27/+0.34), resulting in a
reduced chi-squared of 0.89 (75 d.o.f.) and a fluence of 1.3e-05 ergs/cm^2
(90% confidence level), in the same energy range. The MCAL light curve can
be found at:
http://www.agilescienceapp.it/notices/075364_GRB211023A_562079268.000000.png
.

Additional analysis of AGILE data is in progress. Automatic MCAL GRB alert
Notices can be found at: https://gcn.gsfc.nasa.gov/agile_mcal.html.


GRB_name: GRB211023A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30970
SUBJECT: Fermi GRB 211023A: Global MASTER-Net observations report 
DATE:    21/10/24 11:00:15 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, E. Gorbovskoy, V.Kornilov, N.Tyurina, P.Balanutsa, A.Kuznetsov, F.Balakin, 
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, T.Pogrosheva,
D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev, O.Ershova 
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

V. Yurkov, A. Gabovich, Yu. Sergienko 
(Blagoveschensk Educational State University)




MASTER-Kislovodsk robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 211023A ( Fermi GBM team, GCN 30958) errorbox  7595 sec after notice time and 7627 sec after trigger time at 2021-10-23 15:12:50 UT, with upper limit up to  18.9 mag. Observations started at twilight.  The observations began at zenith distance = 53 deg. The sun  altitude  is -11.0 deg. 

The galactic latitude b = 24 deg., longitude l = 131 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1762531

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

    7657 | 2021-10-23 15:12:50 |   MASTER-Kislovodsk | (04h 49m 25.33s , +80d 59m 06.4s) |   C |    60 | 17.6 |        
    7657 | 2021-10-23 15:12:50 |   MASTER-Kislovodsk | (05h 14m 59.29s , +80d 31m 48.1s) |   C |    60 | 18.0 |        
    7737 | 2021-10-23 15:14:10 |   MASTER-Kislovodsk | (06h 05m 53.66s , +82d 52m 16.2s) |   C |    60 | 17.6 |        
    7738 | 2021-10-23 15:14:10 |   MASTER-Kislovodsk | (06h 38m 00.47s , +82d 24m 21.4s) |   C |    60 | 18.1 |        
    7818 | 2021-10-23 15:15:30 |   MASTER-Kislovodsk | (04h 03m 55.16s , +82d 55m 29.7s) |   C |    60 | 17.6 |        
    7818 | 2021-10-23 15:15:30 |   MASTER-Kislovodsk | (04h 35m 48.63s , +82d 26m 44.7s) |   C |    60 | 18.3 |        
    7898 | 2021-10-23 15:16:50 |   MASTER-Kislovodsk | (06h 14m 35.51s , +84d 16m 43.5s) |   C |    60 | 18.5 |        
    7978 | 2021-10-23 15:18:11 |   MASTER-Kislovodsk | (06h 26m 03.45s , +80d 59m 05.9s) |   C |    60 | 17.8 |        
    8739 | 2021-10-23 15:30:52 |   MASTER-Kislovodsk | (04h 49m 49.99s , +81d 01m 17.2s) |   C |    60 | 17.9 |        
    8739 | 2021-10-23 15:30:52 |   MASTER-Kislovodsk | (05h 15m 18.70s , +80d 34m 03.5s) |   C |    60 | 18.9 |        
    8820 | 2021-10-23 15:32:12 |   MASTER-Kislovodsk | (06h 06m 13.17s , +82d 53m 02.8s) |   C |    60 | 17.9 |        
    8820 | 2021-10-23 15:32:12 |   MASTER-Kislovodsk | (06h 38m 08.10s , +82d 25m 14.9s) |   C |    60 | 18.8 |        
    8900 | 2021-10-23 15:33:32 |   MASTER-Kislovodsk | (04h 04m 13.51s , +82d 56m 18.7s) |   C |    60 | 18.1 |        
    8900 | 2021-10-23 15:33:32 |   MASTER-Kislovodsk | (04h 35m 54.56s , +82d 27m 46.4s) |   C |    60 | 18.9 |        
    8980 | 2021-10-23 15:34:52 |   MASTER-Kislovodsk | (05h 32m 37.45s , +84d 47m 34.5s) |   C |    60 | 18.1 |        
    8980 | 2021-10-23 15:34:52 |   MASTER-Kislovodsk | (06h 14m 59.02s , +84d 17m 59.9s) |   C |    60 | 18.9 |        
    9060 | 2021-10-23 15:36:13 |   MASTER-Kislovodsk | (06h 26m 19.59s , +80d 57m 45.3s) |   C |    60 | 18.2 |        
    9822 | 2021-10-23 15:48:54 |   MASTER-Kislovodsk | (04h 49m 45.52s , +80d 59m 47.8s) |   C |    60 | 17.9 |        
    9822 | 2021-10-23 15:48:54 |   MASTER-Kislovodsk | (05h 15m 14.78s , +80d 32m 34.9s) |   C |    60 | 18.8 |        
   10503 | 2021-10-23 16:00:16 |   MASTER-Kislovodsk | (06h 08m 19.72s , +82d 54m 05.0s) |   C |    60 | 18.0 |        
   10503 | 2021-10-23 16:00:16 |   MASTER-Kislovodsk | (06h 38m 33.51s , +82d 25m 32.3s) |   C |    60 | 18.8 |        
   10583 | 2021-10-23 16:01:36 |   MASTER-Kislovodsk | (04h 06m 04.03s , +82d 55m 51.3s) |   C |    60 | 18.0 |        
   10583 | 2021-10-23 16:01:36 |   MASTER-Kislovodsk | (04h 35m 57.28s , +82d 27m 01.3s) |   C |    60 | 18.9 |        
   10664 | 2021-10-23 16:02:56 |   MASTER-Kislovodsk | (05h 35m 10.07s , +84d 49m 07.8s) |   C |    60 | 18.1 |        
   10664 | 2021-10-23 16:02:56 |   MASTER-Kislovodsk | (06h 15m 13.89s , +84d 18m 52.0s) |   C |    60 | 18.9 |        
   10744 | 2021-10-23 16:04:16 |   MASTER-Kislovodsk | (06h 27m 59.93s , +80d 59m 13.0s) |   C |    60 | 18.1 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB211023B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30972
SUBJECT: GRB 211023B: TSHAO optical observation
DATE:    21/10/24 13:54:08 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

A. Pozanenko (IKI), I. Reva (FAP), M.Krugov (FAP), S. Belkin (IKI), V. 
Kim (FAP),  N. Pankov (HSE) report on behalf of GRB-IKI-FuN:

We observed the field of possible short GRB 211023B detected by Swift 
(Dichiara  et al., GCN  30960)  with Zeiss-1000 telescope of Tien Shan 
Astronomical Observatory stating on Oct. 23 (UT) 21:17:06. We obtained 
series with 120 sec expositions in R-filter.

Within enhanced Swift-XRT position  (Beardmore et al., GCN  30966) we do 
not detected any source (see upper limits below). In particular we do 
not detect possible optical afterglow (Dichiara  et al., GCN  30960). 
  Preliminary photometry of   stacked images   is following

Date       UT start t-T0    Filter  Exp.  OT    Err.  UL(3 sigma)
                     (mid, days)     (s)

2021-10-23 21:17:06 0.01127  R      5*120 n/d n/d     18.9
2021-10-23 21:17:06 0.02238  R     21*120 n/d n/d     19.5

The photometry is based on nearby USNO-B1.0 stars.

In addition we found a source in Legacy Survey 
(https://www.legacysurvey.org) which is coincident with UVOT detection 
(Dichiara  et al., GCN  30960).
This is a point-like object at ~0.67 arces distance from UVOT position 
and has a LS DR9 photometry
g=24.32, r=24.36, z=23.31


GRB_name: GRB211023B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30973
SUBJECT: GRB 211023B: RATIR Optical and NIR Upper Limits 
DATE:    21/10/24 14:34:57 GMT
FROM:    Alan M Watson at UNAM  <alan@astro.unam.mx>

Alan M. Watson (UNAM), Nat Butler (ASU), Alexander Kutyrev (GSFC), William H.
Lee (UNAM), Eleonora Troja (GSFC), Michael G. Richer (UNAM), Ori Fox (STScI), J.
Xavier Prochaska (UCSC), Josh Bloom (UCB), Enrico Ramirez-Ruiz (UCSC), JesÃºs
GonzÃ¡lez (UNAM), Carlos RomÃ¡n-ZÃºÃ±iga (UNAM), Harvey Moseley (GSFC), Rosa L.
Becerra (UNAM), Simone Dichiara (UMD), and OcÃ©lotl LÃ³pez (UNAM) report:

We observed the field of GRB 211023B (Dichiara et al., GCN 30960) with the
Reionization and Transients Infrared Camera (RATIR) on the 1.5m Harold Johnson
Telescope at the Observatorio AstronÃ³mico Nacional on Sierra San Pedro MÃ¡rtir
from 2021/10 24.49 to 2021/10 24.53 UTC (14.54 to 15.54 hours after the BAT
trigger), obtaining a total of 0.73 hours exposure in the r and i bands and 0.30
hours exposure in the Z, Y, J, and H bands.

For a source within the UVOT error circle, in comparison with the SDSS DR9 and
2MASS catalogs, we obtain the following detections and upper limits (3-sigma):

  r > 22.4
  i > 22.1
  Z > 20.6
  Y > 20.3
  J > 21.0
  H > 20.7

These magnitudes are in the AB system and are not corrected for Galactic
extinction in the direction of the GRB.

We thank the staff of the Observatorio AstronÃ³mico Nacional in San Pedro MÃ¡rtir.


GRB_name: GRB211024A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30974
SUBJECT: GRB 211024A: GECAM detection
DATE:    21/10/24 14:44:10 GMT
FROM:    Shuo Xiao at IHEP  <xiaoshuo@ihep.ac.cn>

S. Xiao, Yi Zhao, S. L. Xiong, C. Cai, J. J. He, Y. Huang, Z. W. Guo, 
C. Y. Li, X. B. Li, J. C. Liu, X. Y. Song, C. W. Wang, P. Wang, S. L. Xie, W. C. Xue,
Q. B. Yi, Y. Q. Zhang, G. Y. Zhao, X. Y. Zhao, C. Zheng, Y. Q. Du, D. Y. Guo, 
J. Liang, F. J. Lu, Q. Luo, X. Ma, W. X. Peng, R. Qiao, L. M. Song, J. Wang, H. Wu, 
P. Zhang, S. N. Zhang, X. L. Zhang, Z. Zhang, S. J. Zheng (IHEP),
report on behalf of GECAM team:

During the commissioning phase, GECAM-B was triggered ground by a short
bright burst, GRB 211024A, at 2021-10-24T01:34:11.450 UTC (denoted as T0),
which was also detected by Fermi/GBM (GCN 30962).
According to the GECAM-B light curves in about 16-3500 keV, this 
burst mainly consists of a broad pulse with a duration of about 0.1 s.

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/tn211024_013411_gb.png

GECAM-B localized this burst to the following position (J2000):
Ra: 25.7 deg 
Dec: 1.05 deg
Err: 28.73 deg (1-sigma, statistical only)
The current systematic error of location is estimated to be several degrees 
which could be minimized by the ongoing calibration.

This location is consistent with Fermi/GBM position within the error.

Please note that all GECAM results here are preliminary. The final analysis
will be published in journal papers or GECAM online catalog.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor
(GECAM) mission consists of two small satellites (GECAM-A and GECAM-B) in
Low Earth Orbit (600 km, 29 deg), launched on Dec 10, 2020 (Beijing Time),
which was funded by the Chinese Academy of Sciences (CAS).


GRB_name: GRB211023B
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30975
SUBJECT: GRB 211023B: Swift/UVOT Detection
DATE:    21/10/24 18:21:49 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

N. P. M. Kuin (UCL-MSSL) and S. Dichiara (NASA/GSFC/UMCP) report
on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 211023B
98 s after the BAT trigger (Dichiara et al., GCN Circ. 30960).
A source consistent with the XRT position (Beardmore et al. GCN Circ. 30966)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
    RA  (J2000) =  11:21:14.33 = 170.30971 (deg.)
    Dec (J2000) = +39:08:08.8  =  39.13579 (deg.)
with an estimated uncertainty of 0.53 arc sec. (radius, 90% confidence).

Preliminary detections and 3-sigma upper limits using the UVOT photometric
system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures
are:

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

white               98          247          147         19.44 +/- 0.11
v                  640         1753          136        >18.8
b                  566         1679          117        >19.9
u                  310          734          265         19.50 +/- 0.20
w1                 690         1803          117        >19.3
w2                 615         1039           39        >19.9

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.024 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB211023B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30976
SUBJECT: GRB 211023B: BOOTES-4/MET and 1.5m OSN optical upper limit
DATE:    21/10/24 20:31:50 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

Y.-D. Hu, V. Casanova, T.-R. Sun, A. J. Castro-Tirado, M. D. Caballero-Garcia, M. A. Castro Tirado, E. Fernandez-Garcia (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), S. Guziy (Univ. of Nikolaev) and D. R. Xiong, Y. F. Fan, J. M. Bai, C. J. Wang, Y. X. Xin, X. H. Zhao (Yunnan Observatories of CAS) on behalf of a larger collaboration, report:

Following the detection of GRB 211023B by Swift (S. Dichiara et al. GCNC 30960), the 0.6m BOOTES-4/MET robotic telescope at Lijiang Astronomical Observatory (China) automatically respond to this burst starting on Oct 23 at 21:06:20 UT (~28 sec after trigger). Due to technical problems, the useful images were obtained only after 21:18:39 UT (~13 min after trigger). The optical afterglow reported by Swift/UVOT (S. Dichiara et al. GCNC 30960, N. P. M. Kuin et al. GCNC 30975) is not detected in the co-added image (10s x 30, clear filter) down to 19.9 mag.

We then triggered the 1.5m OSN telescope in Sierra Nevada Observatory (Granada, Spain) on Oct. 24 03:20 UT (~6.2 hrs after trigger). A series of image were taken in R and I -bands (300s exposures each filter). The optical afterglow is not detected in the co-added image (300s x 12) down to 21.6 mag (R-band).

These non-detections are consistent with the reports by MASTER (Lipunov et al. GCNC 30964), TSHAO (Pozanenko et al. GCNC 30972) and RATIR (Watson et al. GCNC 30973).

We thank the staff at Lijiang observatory and OSN for their excellent support.


GRB_name: GRB211023A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30977
SUBJECT: GRB 211023A: MASTER OT J045237.07+851925.2 - optical counterpart discovery
DATE:    21/10/24 20:36:12 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

K.Zhirkov, V. Lipunov, E.Gorbovskoy, P.Balanutsa, A.Kuznetsov, O.Gress, G.Antipov, D. Vlasenko,
N.Tiurina, D.Zimnukhov, V.Senik,V.Topolev, A.Chasovnikov, E.Minkina, V.Grinshpun, D.Cheryasov (Lomonosov MSU,SAI,PhysicsDepartment),
R. Rebolo, M. Serra(The Instituto de Astrofisica de Canarias),
D. Buckley (South African Astronomical Observatory),
O.A. Gres, N.M. Budnev (Irkutsk State University, API),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico FelixAguilar OAFA),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity)

MASTER Global robotic net (MASTER-Net:http://observ.pereplet.ru Lipunov et  al.,2010,Advances in Astronomy,2010,30L)
started inspect of the FERMI GRB 211023A ( Fermi GBM team, GCN 30958,ttrigger=13:05:43, Fermi LAT GCN 30961)
  errorbox just after sunset at 2021-10-23 15:12:50 UT (Lipunov et al. GCN 30970).

MASTER OT J045237.07+851925.2 discovery

MASTER-Kislovodsk auto-detection system ( Lipunov et al., "MASTER Global Robotic Net", Advances in Astronomy, 2010, 30L )
  discovered OT source - optical counterpart of this GRB
at (RA, Dec) = 04h 52m 37.07s +85d 19m 25.2s at  2021-10-23.65385 UT.

Fast changing OT unfiltered magnitude at one of first images is 15.6m (mlim=18.9).

There is no minor planet in MPC and any sources in VIZIER  at this place.

We have reference image on 2017-01-28.75669 UT with  unfiltered mlim=19.9m.

Deep images and possibly host galaxy  spectral observations are required.


GRB_name: GRB211023B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30979
SUBJECT: GRB 211023B: Swift-BAT refined analysis
DATE:    21/10/24 20:56:12 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

S. Laha (GSFC/UMBC), S. D. Barthelmy (GSFC), S. Dichiara (NASA/GSFC/UMCP),
H. A. Krimm (NSF), A. Y. Lien (U Tampa), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU),
M. Stamatikos (OSU) (i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 211023B (trigger #1080859)
(Dichiara, et al., GCN Circ. 30960).  The BAT ground-calculated position is
RA, Dec = 170.314, 39.133 deg which is 
  RA(J2000)  =  11h 21m 15.3s 
  Dec(J2000) = +39d 07' 58.7" 
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 48%.

The mask-weighted light curves shows a single peak from approximately T+0
to T+1.5 seconds.   T90 (15-350 keV) is 1.30 +- 0.26 sec (estimated error including 
systematics).

The time-averaged spectrum from T-0.01 to T+1.45 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.97 +- 0.24.  The fluence in the 15-150 keV band is 1.7 +- 0.3 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+0.24 sec in the 15-150 keV band
is 2.2 +- 0.3 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1080859/BA/


GRB_name: GRB211024B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30980
SUBJECT: GRB 211024B: Swift detection of a burst
DATE:    21/10/24 22:34:22 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

J.D. Gropp (PSU), N. J. Klingler (GSFC/UMBC/CRESSTII),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC), D. M. Palmer (LANL),
T. M. Parsotan (GSFC/UMBC/CRESSTII), M. H. Siegel (PSU) and
A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 22:20:36 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 211024B (trigger=1081073).  Swift slewed immediately to
the burst, but immediately slewed away due to a conflicting observation. 
The BAT on-board calculated location is 
RA, Dec 154.688, +24.579 which is 
   RA(J2000) = 10h 18m 45s
   Dec(J2000) = +24d 34' 43"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single-peaked
structure with a duration of about 70 sec.  The peak count rate
was ~1500 counts/sec (15-350 keV), at ~7 sec after the trigger. 

Because of a conflicting preplanned observation, there was
no immediate XRT or UVOT observation.  A target of opportunity
observation is planned. 

Burst Advocate for this burst is J.D. Gropp (jdg44 AT psu.edu). 
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)


GRB_name: GRB211024B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30981
SUBJECT: Swift GRB 211024B: Global MASTER-Net observations report 
DATE:    21/10/25 00:10:41 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, 
D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, T.Pogrosheva, E.Minkina,
A.Chasovnikov, V.Topolev, V.Grinshpun, D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

A. Gabovich, V.Yurkov 
(Blagoveschensk Educational State University)


MASTER-Tavrida robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Lomonosov MSU, SAI Crimea astronomical station) was pointed to the Swift GRB 211024B ( J.D. Gropp et al., GCN 30980) errorbox  5877 sec after notice time and 5966 sec after trigger time at 2021-10-25 00:00:02 UT, with upper limit up to  15.6 mag. The observations began at zenith distance = 70 deg. The sun  altitude  is -44.2 deg. 

The galactic latitude b = 56 deg., longitude l = 209 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1764215

We obtain a following upper limits.  

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

    6056 |      MASTER-Tavrida |   C |   180 | 15.6 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB211023A
Detection_method: Fermi LAT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30982
SUBJECT: GRB 211023A: OAJ Bright Afterglow Confirmation
DATE:    21/10/25 00:45:45 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/DARK/NBI), C. C. 
Thoene, M. Blazek, J. F. Agui Fernandez (all HETH/IAA-CSIC), 
Iglesias-Marzoa, R., and Lacruz, E. (both OAJ) report:

We observed the Fermi-LAT position (Di Lalla et al., GCN #30961) of the 
bright Fermi GRB 211023A (Fermi detection: Fermi GBM Team, GCN #30958; 
Lesage et al., GCN #30965; AGILE detection: Ursi et al., GCN #30969) 
with the JAST/T80 telescope of OAJ, Teruel, Spain. We obtained 3 x 300 s 
images each in g', r', and i' under good conditions.

At the position of the MASTER afterglow candidate (Zhirkov et al., GCN 
#30977), we detect a bright source which is not visible in Pan-STARRS 
archival imaging. Against three Pan-STARRS comparison stars, we measure 
r' = 18.03 +/- 0.02 mag (AB mag) at 0.5704 d after the GRB.

We note this is an exceedingly bright afterglow, just slightly fainter 
at similar times than those of GRBs 130427A and 181201A. We also note a 
resemblance in prompt emission shape, fluence (S. Poolakkil, priv. 
comm.), and peak energy to the famous GRB 030329. Spectroscopic 
observations and further follow-up are encouraged.


GRB_name: GRB210919A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30983
SUBJECT: GRB 210919A: FORS2/VLT observations
DATE:    21/10/25 00:51:58 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

D. A. Kann (HETH/IAA-CSIC), D. B. Malesani (Radboud U. Nijmegen), V. 
D'Elia (ASI/SSDC, INAF/OAR), A. de Ugarte Postigo (HETH,DARK/NBI), A. 
Rossi (INAF-OAS) and C. C. Thoene (HETH/IAA-CSIC) report on behalf of 
the Stargate consortium:

We observed the field of the short GRB 210919A (Tohuvavohu et al., GCN 
#30846) at late times with FORS2 mounted on the ESO VLT at Cerro Paranal 
Observatory, Chile. We obtained 6 x 90 s exposure each in V, Rc, and Ic, 
and 12 x 68 s in z_special, under excellent conditions (seeing 0".9 to 
0".65 from V to z), on October 2.28 UT, 2021, at a midtime of 13.26 days 
after the GRB.

Our results are in agreement with the LDT/LMI observations obtained by 
O'Connor et al. (GCN #30934). At the position of the potential afterglow 
(Kann et al., GCN #30883, #30884), we do not detect any source. 
Calibrating against three nearby stars from the Pan-STARRS catalog 
(converted to Johnson-Cousins filters for V, Rc, Ic, following the 
Lupton transformations, then converted back to AB magnitudes), we derive 
an upper limit of Ic > 25.8 mag, with the V, Rc observations reaching a 
comparable depth and the z observation being shallower.

The nearby source reported by O'Connor et al. (GCN #30934) is detected 
in all filters, and we find that it is marginally extended. We measure, 
again in AB magnitudes, Ic = 23.83 +/- 0.06 mag in an aperture 
corresponding to the stellar PSF, it being somewhat brighter using a 
larger aperture. Therefore, this object is a host galaxy candidate for 
GRB 210919A, in agreement with O'Connor et al. (GCN #30934).

At the eastern edge of the XRT error circle (Goad et al., GCN #30850), 
we find a further, fainter source at RA = 5:21:01.35, Dec. = +1:18:41.9 
(J2000) with an error of 0".5. For this source, we measure Ic = 25.01 
+/- 0.19 mag. As the source is faint, we can't make any definite 
statements about its extension. It is also a host galaxy candidate, 
although its chance association probability is quite large.


GRB_name: GRB211024B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30984
SUBJECT: GRB 211024B: Nanshan/NEXT optical afterglow detection
DATE:    21/10/25 01:27:33 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

Z.P. Zhu (NAOC, HUST), S.Y. Fu, X. Liu, D. Xu (NAOC), X. Gao (Urumqi 
No.1 Senior High School), J.Z. Liu (XAO) report:

We observed the field of GRB 211024B (Gropp et al., GCN 30980) using the 
NEXT-0.6m optical telescope located at Nanshan, Xinjiang, China. 
Observations automatically started at 22:23:13 UT on 2021-10-24, i.e., 
157 s after the BAT trigger. A series of 3x40 s, 3x60 s and 12x90 s 
frames in the Sloan r-filter were obtained.

An uncatalogued evolving optical transient is detected within the 
Swift/BAT error circle (Gropp et al., GCN 30980), at coordinates

R.A. =  10:18:51.12
Dec. = +24:34:05.16

with an uncertainty of 0.5 arcsec. The OT had r = 18.4 +/- 0.1 mag in 
our first image, brightened to a peak of r ~ 17.6 at ~ 378 s, and then 
faded with a powerlaw decay as F(t) ~ t^-0.94, all calibrated with 
nearby PS1 stars. We thus conclude that the OT is the optical afterglow 
of the burst.


GRB_name: GRB211025A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30986
SUBJECT: GRB 211025A: Swift detection of a burst
DATE:    21/10/25 05:29:36 GMT
FROM:    Aaron Tohuvavohu at U Toronto  <aaron.tohu@gmail.com>

J.D. Gropp (PSU), D. M. Palmer (LANL), B. Sbarufatti (PSU) and
A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 05:10:20 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 211025A (trigger=1081113).  Swift slewed immediately to the burst.
The BAT on-board calculated location is
RA, Dec 162.377, +31.557 which is
   RA(J2000) = 10h 49m 30s
   Dec(J2000) = +31d 33' 26"
with an uncertainty of 3 arcmin (radius, 90% containment, including
systematic uncertainty).  As is usual for an image trigger, the
immediately available BAT lightcurve is unclear, but there does
appear to be a peak between T+30 and T+64, with a peak count rate
of ~300 counts/s (15-350 kev) at ~38 s after the nominal trigger time.

The XRT began observing the field at 05:12:23.2 UT, 123.3 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 162.38427, 31.51343 which
is equivalent to:
   RA(J2000)  = 10h 49m 32.22s
   Dec(J2000) = +31d 30' 48.3"
with an uncertainty of 4.1 arcseconds (radius, 90% containment). This
location is 158 arcseconds from the BAT onboard position, within the
BAT error circle. This position may be improved as more data are
received; the latest position is available at
https://www.swift.ac.uk/sper.  We cannot determine whether the source
is fading at the present time. No spectrum from the promptly downlinked
event data is yet available to determine the column density.

The initial flux in the 2.5 s image was 5.36e-09 erg cm^-2 s^-1 (0.2-10
keV).

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 131 seconds after the BAT trigger. No credible afterglow candidate has
been found in the initial data products. The 2.7'x2.7' sub-image processing
FAILED because of no aspect solution. Results from the list of sources
generated on-board are not available at this time. No correction has been made
for the expected extinction corresponding to E(B-V) of 0.027.

Burst Advocate for this burst is J.D. Gropp (jdg44 AT psu.edu).
Please contact the BA by email if you require additional information
regarding Swift followup of this burst. In extremely urgent cases, after
trying the Burst Advocate, you can contact the Swift PI by phone (see
Swift TOO web site for information: http://www.swift.psu.edu/)


GRB_name: GRB211025A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30987
SUBJECT: GRB 211025A: Enhanced Swift-XRT position
DATE:    21/10/25 09:46:31 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans, M.R. Goad, J.P. Osborne and A.P. Beardmore (U. Leicester) 
report on behalf of the Swift-XRT team.

Using 2418 s of XRT Photon Counting mode data and 5 UVOT
images for GRB 211025A, we find an astrometrically corrected X-ray
position (using the XRT-UVOT alignment and matching UVOT field sources
to the USNO-B1 catalogue): RA, Dec = 162.38304, +31.51233 which is equivalent
to:

RA (J2000): 10h 49m 31.93s
Dec (J2000): +31d 30' 44.4"

with an uncertainty of 2.1 arcsec (radius, 90% confidence).

This position may be improved as more data are received. The latest
position can be viewed at http://www.swift.ac.uk/xrt_positions. Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and Evans
et al. (2009, MNRAS, 397, 1177).

This circular was automatically generated, and is an official product of the
Swift-XRT team.


GRB_name: GRB210610B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30988
SUBJECT: GRB 210610B: Sintesz-Newton/CrAO optical observations
DATE:    21/10/25 12:07:05 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

N. Pankov (HSE), S. Nazarov (CrAO), A. Pozanenko (IKI), S. Belkin (IKI, 
HSE)  report on behalf of IKI GRB FuN:

We observed  the GRB 210610B (Page  et al., GCN 30170) with 
Sintesz-Newton 350mm f/5 telescope of CrAO observatory. Observation 
started on 2021-06-10 (UT) 22:07:10, and continued on   2021-06-11 (UT) 
20:22:38,  2021-06-12 (UT) 20:39:03, and 2021-06-13 (UT) 19:38:28. The 
series consists of images with an exposure of 300 s in a Clear filter.

The optical afterglow  first reported by UVOT team (Page  et al., GCN 
30170) is clearly detected in each epoch.

Preliminary photometry of the stacked images is following

Date       UT start   t-T0    Filter Exp.     OT    err   UL(3)
                      (mid, days)       (s)

2021-06-10 22:07:10   0.10293  Clear 5*300    17.20 0.03  20.5
2021-06-10 n/d        0.12658  Clear 5*300    17.28 0.08  21.1
2021-06-10 n/d        0.14409  Clear 5*300    17.28 0.06  21.1
2021-06-10 n/d        0.16159  Clear 5*300    17.29 0.06  21.1
2021-06-11 20:22:38   1.02165  Clear 8*300    19.58 0.10  21.2
2021-06-11 20:50:32   1.04103  Clear 6*300    19.50 0.09  21.2
2021-06-11 21:33:21   1.07077  Clear 17*300   19.69 0.09  21.5
2021-06-12 20:39:03   2.03479  Clear 14*300   20.57 0.19  21.5
2021-06-13 19:38:28   3.02571  Clear 20*300   21.26 0.17  21.8

The photometry is based on nearby USNO-B1.0 (R2) stars
USNO_B10-1043-00282648
USNO_B10-1043-00282621


GRB_name: GRB211024B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30989
SUBJECT: GRB 211024B: Swift-BAT refined analysis
DATE:    21/10/25 13:03:36 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

A. Y. Lien (U Tampa), S. D. Barthelmy (GSFC), J.D. Gropp (PSU),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),A. Y. Lien (U Tampa),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), T. Parsotan (GSFC/UMBC),
T. Sakamoto (AGU), M. Stamatikos (OSU) (i.e. the Swift-BAT team):

Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 211024B (trigger #1081073)
(Gropp, et al., GCN Circ. 30980).  The BAT ground-calculated position is
RA, Dec = 154.708, 24.566 deg which is
     RA(J2000)  =  10h 18m 49.9s
     Dec(J2000) = +24d 33' 57.3"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.

The mask-weighted light curve shows three episodes.  The first episode
starts from T-60 s, peaks at T+10 s and ends at T+100 s.  The second, and
weakest, episode runs from T+250 to T+400 sec and the third episode starts
around T+500 s, peaks at T+580 s and ends at T+620 s.  The burst came into
the BAT field of view around T-100 sec during a pre-planned slew.
T90 (15-350 keV) is 603.5 +- 20.7 sec (estimated error including systematics).

The time-averaged spectrum from T-56.37 to T+613.08 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.63 +- 0.09.  The fluence in the 15-150 keV band is 6.8 +- 0.3 x 10^-6 erg/cm2.
The 1-sec peak photon flux measured from T+5.17 sec in the 15-150 keV band
is 0.9 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1081073/BA/


GRB_name: GRB211023A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30990
SUBJECT: GRB 211023A: 1.5m OSN optical observation
DATE:    21/10/25 13:24:27 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

Y.-D. Hu, V. Casanova, T.-R. Sun, A. J. Castro-Tirado, M. D. Caballero-Garcia, M. A. Castro Tirado and E. Fernandez-Garcia (IAA-CSIC), on behalf of a larger collaboration, report:

Following the detection of GRB 211023A by Fermi (GCN 30958) and AGILE (Ursi et al. GCNC 30969), images in BVRI bands were obtained at the 1.5m OSN telescope in Sierra Nevada Observatory (Granada, Spain) starting on 24 Oct 22:57 UT. In the first R-band 90 s exposure image, the optical afterglow discovered by MASTER (Zhirkov et al. GCNC 30977) and also reported at OAJ (Kann et al. GCNC 30982) is clearly detected, for which we measure R = 19.27 +/- 0.14 (~1.4 d after trigger). Further observations are ongoing.

We thank the staff at OSN for their excellent support.


GRB_name: GRB211025A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30991
SUBJECT: GRB 211025A: Swift/UVOT Detection 
DATE:    21/10/25 14:35:00 GMT
FROM:    Samantha Oates at MSSL  <samantha.oates@alumni.ucl.ac.uk>

S. R. Oates (U.Birmingham) and J. D. Gropp (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 211025A
131 s after the BAT trigger (Gropp et al., GCN Circ. 30986).
A source consistent with the XRT position (Evans et al. GCN Circ. 30987)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
 RA  (J2000) =  10:49:31.93 = 162.38304 (deg.)
 Dec (J2000) = +31:30:44.3  =  31.51231 (deg.)
with an estimated uncertainty of 0.9 arc sec. (radius, 90% confidence).

Preliminary detections and 3-sigma upper limits using the UVOT photometric
system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures
are:

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag
white_FC           131          281          147       > 20.2
white              131          943          220       19.90 +/- 0.25
white             5965         6164          197       > 20.4
v                 4940         6509          329       > 19.0
b                 5760         5960          197       > 19.8 
uvw1               669          688           19       > 17.5
uvw1              5350         5550          197       > 19.5
uvm2              5145         5345          197       > 19.4
uvw2              4735         6370          393       > 20.0  

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.027 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB211023B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30992
SUBJECT: Possible Short GRB 211023B: CAHA 2.2m Detection
DATE:    21/10/25 14:56:49 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH/DARK/NBI), C. C. 
Thoene, M. Blazek, J. F. Agui Fernandez (all HETH/IAA-CSIC), A. 
Guijarro, and P. Martin-Fernandez (both CAHA) report:

We observed the optical afterglow of the potentially short Swift GRB 
211023B (Dichiara et al., GCN #30960; Kuin & Dichiara, GCN #30975) with 
CAFOS mounted on the 2.2m Telescope at Calar Alto, Almeria, Spain. We 
obtained 30 x 90 s in the SDSS i' band under mediocre conditions.

At the position of the GRB afterglow discovered by Swift/UVOT (Kuin & 
Dichiara, GCN #30975), we detect a source. Against two Pan-STARRS 
comparison stars, we measure:

i' = 22.26 +\- 0.10 mag (AB) at 0.3091 d after the GRB.

We note this faint magnitude is in agreement with both earlier (Lipunov 
et al., GCN #30964; Pozanenko et al., GCN #30972; Yu et al., GCN 
#30976), simultaneous (Yu et al., GCN #30976), and later (Watson et al., 
GCN #30973) non-detections.


GRB_name: GRB211019A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30993
SUBJECT: IPN Triangulation of GRB 211019A
DATE:    21/10/25 15:02:56 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the MGNS/BepiColombo and HEND/Mars Odyssey teams,

J. Benkhoff on behalf of the BepiColombo team,

K. Hurley on behalf of the IPN,

D. Svinkin, S. Golenetskii, D. Frederiks, A. Ridnaia,
A. Lysenko, and T. Cline on behalf of the Konus-Wind team,

A. Goldstein, M. S. Briggs, and C. Wilson-Hodge
on behalf of the Fermi GBM team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

and

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:

The bright, long-duration GRB 211019A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 30941;
BALROG localization: F. Kunzweiler et al., GCN Circ. 30942;
GRBAlpha detection: J. Ripa et al., GCN Circ. 30946)
was detected by BepiColombo (MGNS; see introductory GCN Circ. 30949),
Mars-Odyssey (HEND), GRBAlpha, Fermi (GBM trigger 656315976),
Konus-Wind, and INTEGRAL (SPI-ACS), at about 21571 s UT (05:59:31).

The burst light curves in the energy range 30 keV-1.5 MeV (HEND) and
250-450 keV (MGNS) exhibit a bright peak with a total duration of ~17 s.

We have triangulated GRB 211019A to the following 3 sigma annuli:
---------------------------------------------------------
           R.A.(J2000)  Dec.(J2000)    R      +dR     -dR
               deg         deg        deg     deg     deg
---------------------------------------------------------
MGNS-HEND    27.190     10.927     89.034  +0.021  -0.022
Konus-HEND  200.705     -8.093     87.815  +0.017  -0.017
Konus-GBM   190.965     -7.594     80.456  +0.431  -0.431
---------------------------------------------------------
The MGNS-HEND and Konus-HEND annuli intersect to form two error
boxes one of which is inconsistent with the Konus-GBM annulus,
the KW ecliptic latitude response,
and the Fermi (GBM) RoboBA and BALROG localizations.

The correct preliminary, 3 sigma error box is:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   106.988 (07h 07m 57s) -38.779 (-38d 46' 43")
  Corners:
   106.975 (07h 07m 54s) -38.728 (-38d 43' 41")
   106.898 (07h 07m 36s) -39.122 (-39d 07' 19")
   107.002 (07h 08m 01s) -38.819 (-38d 49' 07")
   107.079 (07h 08m 19s) -38.424 (-38d 25' 25")
  ---------------------------------------------
The error box area is 49 sq. arcmin, and its maximum
dimension is 43 arcmin (the minimum one is 2.0 arcmin).
The Sun distance was 89 deg.

This box may be improved.

A triangulation maps are posted at:
http://www.ioffe.ru/LEA/GRBs/GRB211019_T21573/IPN/
and
http://l503.iki.rssi.ru/owncloud/index.php/s/bRzLdux7RLz1tVf


GRB_name: GRB211024B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30994
SUBJECT: GRB 211024B: Swift-XRT refined Analysis
DATE:    21/10/25 15:12:58 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), E. Ambrosi 
(INAF-IASFPA) , M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR),
J. D. Gropp (PSU), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), K.L.
Page (U. Leicester) and J.D. Gropp report on behalf of the Swift-XRT
team:

We have analysed 6.2 ks of XRT data for GRB 211024B (Gropp et al. GCN
Circ. 30980), from 105 s to 24.7 ks after the  BAT trigger. The data
comprise 6 s in Windowed Timing (WT) mode (taken while Swift was
slewing), with the remainder in Photon Counting (PC) mode. Using 6214 s
of PC mode data and 12 UVOT images, we find an enhanced XRT position
(using the XRT-UVOT alignment and matching UVOT field sources to the
USNO-B1 catalogue): RA, Dec = 154.71268, +24.56825 which is equivalent
to:

RA (J2000): 10h 18m 51.04s
Dec(J2000): +24d 34' 05.7"

with an uncertainty of 1.9 arcsec (radius, 90% confidence).

The late-time light curve (from T0+5.6 ks) can be modelled with a
power-law decay with a decay index of alpha=2.69 (+0.13, -0.12).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.08 (+0.11, -0.10). The
best-fitting absorption column is  9.7 (+2.7, -2.5) x 10^20 cm^-2, in
excess of the Galactic value of 2.1 x 10^20 cm^-2 (Willingale et al.
2013). The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 3.2 x 10^-11 (3.9 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      9.7 (+2.7, -2.5) x 10^20 cm^-2
Galactic foreground: 2.1 x 10^20 cm^-2
Excess significance: 5.0 sigma
Photon index:      2.08 (+0.11, -0.10)

If the light curve continues to decay with a power-law decay index of
2.69, the count rate at T+24 hours will be 5.0 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.6 x
10^-13 (2.0 x 10^-13) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01081073.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB211024B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30995
SUBJECT: GRB 211024B: CAHA 2.2m Detection; ultra-long GRB? 
DATE:    21/10/25 15:45:51 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

D. A. Kann (HETH/IAA-CSIC), A. de Ugarte Postigo (HETH, DARK/NBI), C. C. 
Thoene, M. Blazek, J. F. Agui Fernandez (all HETH/IAA-CSIC), A. 
Guijarro, and P. Martin-Fernandez (both CAHA) report:

We observed the optical afterglow of the very long Swift GRB 211024B 
(Gropp et al., GCN #30980; Zhu et al., GCN #30984) with CAFOS mounted on 
the 2.2m Telescope at Calar Alto, Almeria, Spain. We obtained 30 x 90 s 
in the SDSS i' band under mediocre conditions.

At the position of the GRB afterglow discovered by Nanshan/NEXT (Zhu et 
al., GCN #30984), we detect a source. Against one Pan-STARRS comparison 
star, we measure:

i' = 20.27 +\- 0.05 mag (AB) at 0.2485 d after the GRB.

We note the XRT light curve at time of writing 
(https://www.swift.ac.uk/xrt_curves/01081073/  Evans et al., GCN #30994) 
shows a certain resemblance to that of the ultra-long GRB 111209A, being 
relatively flat until 10 ks before dropping off very steeply. The lack 
of early data prevents further conclusions for now. Further follow-up is 
warranted.


GRB_name: GRB211025A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30996
SUBJECT: GRB 211025A: Swift-XRT refined Analysis
DATE:    21/10/25 15:46:10 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

J.P. Osborne (U. Leicester), M. Capalbi (INAF-IASFPA), M. Perri (SSDC &
INAF-OAR), V. D'Elia (SSDC & INAF-OAR), J.A. Kennea (PSU), A.
Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), K.L. Page (U. Leicester),
A.P. Beardmore (U. Leicester) and J.D. Gropp report on behalf of the
Swift-XRT team:

We have analysed 4.0 ks of XRT data for GRB 211025A (Gropp et al. GCN
Circ. 30986), from 115 s to 28.0 ks after the  BAT trigger. The data
comprise 203 s in Windowed Timing (WT) mode (the first 6 s were taken
while Swift was slewing) with the remainder in Photon Counting (PC)
mode. The enhanced XRT position for this burst was given by Evans et
al. (GCN Circ. 30987).

The late-time light curve (from T0+4.7 ks) can be modelled with a
power-law decay with a decay index of alpha=1.3 (+0.6, -0.4).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.91 (+/-0.06). The
best-fitting absorption column is  7.1 (+/-1.4) x 10^20 cm^-2, in
excess of the Galactic value of 2.4 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.33 (+0.22, -0.12)
and a best-fitting absorption column consistent with the Galactic
value. The counts to observed (unabsorbed) 0.3-10 keV flux conversion
factor deduced from this spectrum  is 2.8 x 10^-11 (3.1 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      2.4 (+3.5, -0.0) x 10^20 cm^-2
Galactic foreground: 2.4 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:      2.33 (+0.22, -0.12)

If the light curve continues to decay with a power-law decay index of
1.3, the count rate at T+24 hours will be 2.1 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 5.8 x
10^-14 (6.4 x 10^-14) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01081113.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB211025A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30997
SUBJECT: GRB 211025A: Swift-BAT refined analysis
DATE:    21/10/25 19:04:28 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

C. B. Markwardt (GSFC), S. D. Barthelmy (GSFC), J.D. Gropp (PSU), 
H. A. Krimm (NSF),S. Laha (GSFC/UMBC), A. Y. Lien (U Tampa),
D. M. Palmer (LANL),T. Parsotan (GSFC/UMBC), T. Sakamoto (AGU),
M. Stamatikos (OSU) (i.e. the Swift-BAT team):

Using the data set from T-239 to T+844 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 211025A (trigger #1081113)
(Gropp, et al., GCN Circ. 30986).  The BAT ground-calculated position is
RA, Dec = 162.407, 31.506 deg which is 
  RA(J2000)  =  10h 49m 37.8s 
  Dec(J2000) = +31d 30' 20.8" 
with an uncertainty of 2.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 100%.

The mask-weighted light curve shows a single broad pulse beginning at T+0,
peaking around T+50 sec and declining to background by T+150 sec. 
T90 (15-350 keV) is 103.5 +- 27.6 sec (estimated error including systematics).
 
The time-averaged spectrum from T+12.32 to T+128.5 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.96 +- 0.28.  The fluence in the 15-150 keV band is 7.7 +- 1.4 x 10^-7 erg/cm2.
The 1-sec peak photon flux measured from T+51.66 sec in the 15-150 keV band
is 0.5 +- 0.1 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1081113/BA/


GRB_name: GRB211023A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  30998
SUBJECT: Correction to GCN 30965: GRB 211023A: Fermi GBM detection
DATE:    21/10/25 19:46:21 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076@uah.edu>

S. Poolakkil (UAH) reports on behalf of the Fermi GBM Team:

"The Fermi Gamma-ray Burst Monitor (GBM) GCN circular for GRB 211023A (S.
Lesage et al. 2021, GCN 30965)
had the event fluence stated incorrectly. The event fluence (10-1000 keV)
for this trigger is
(1.114 +/- 0.007)E-04 erg/cm^2."


GRB_name: GRB211023B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31000
SUBJECT: GRB 211023B: LDT Optical Afterglow Detection
DATE:    21/10/25 23:11:12 GMT
FROM:    Brendan O'Connor at UMD  <oconnorb@umd.edu>

B. O'Connor (UMD, GWU),S.B. Cenko (UMD,NASA-GSFC),
E. Troja (UMD, NASA-GSFC),A.Gottlieb (UMD,NASA-GSFC),
S.Dichiara (PSU),A. Kutyrev (UMD,NASA-GSFC),
S. Veilleux (UMD)

We observed the field of GRB 211023B (Dichiara et al., GCN 30960)
using the Large Monolithic Imager (LMI) on the 4.3m Lowell Discovery
Telescope (LDT) at Happy Jack, AZ. Observations began on October 25,
2021 at 11:42:14 UT (~1.61 d after the GRB), and were performed in
r-band for a total of 18x150 s exposures under poor conditions.

We detect a source coincident with the position of the optical counterpart
reported by UVOT (Kuin et al., GCN 30975) and CAHA (Kann et al., GCN 30992).
We measure a brightness of r~23 AB mag, brighter than the archival object
reported by Pozanenko et al. (GCN 30972). We do not detect any other source
within 5" radius of the UVOT position with a 3-sigma upper limit r>24.0 mag.

Given the non-detection at ~15 hours (Watson et al., GCN 30973),
our detection implies a shallow temporal decay index beta<0.6,
assuming a power-law decline as F~t^-beta. While this may be due
in part to the underlying source (Pozanenko et al., GCN 30972),
we note that the same flattening is also observed in X-rays by Swift/XRT.
Therefore, we strongly encourage continued follow-up of this source.

Magnitudes are calibrated against the SDSS catalog and are not corrected
for Galactic extinction.

We thank the staff of the Lowell Discovery Telescope for assistance
with these observations.


GRB_name: GRB211025A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31001
SUBJECT: Swift GRB 211025A: Global MASTER-Net observations report 
DATE:    21/10/25 23:16:38 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, 
D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, T.Pogrosheva, E.Minkina,
A.Chasovnikov, V.Topolev, V.Grinshpun, D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

A. Gabovich, V.Yurkov 
(Blagoveschensk Educational State University)


MASTER-Kislovodsk robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) was pointed to the Swift GRB 211025A ( J.D. Gropp et al., GCN 30986) errorbox  63953 sec after notice time and 64035 sec after trigger time at 2021-10-25 22:57:35 UT, with upper limit up to  17.5 mag. The observations began at zenith distance = 76 deg. The sun  altitude  is -49.5 deg. 

The galactic latitude b = 64 deg., longitude l = 197 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1764428

We obtain a following upper limits.  

Tmid-T0  |          Site       |Filt.| Expt. | Limit| Comment
_________|_____________________|_____|_______|______|________

   64126 |   MASTER-Kislovodsk |   C |   180 | 17.5 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB211023B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31002
SUBJECT: GRB 211023B: Gemini-North Optical Observations
DATE:    21/10/26 01:38:16 GMT
FROM:    Jillian Rastinejad at Northwestern Univ.  <jillianrastinejad2024@u.northwestern.edu>

J. Rastinejad, K. Paterson, W. Fong, C. Kilpatrick, A. Rouco Escorial (Northwestern), Antonino Cucchiara (College of Marin) report on behalf of a larger collaboration:

We observed the location of GRB 211023B (Dichiara et al. GCNC 30960) over two nights with the Gemini Multi-Object Spectrograph (GMOS) mounted on Gemini-North under Program GN-2021B-Q-109. We obtained 11x60-sec and 20x60-sec imaging in i-band at a mid-time of 2021 October 25.63 UT (0.7484 days post-burst) and 2021October 24.62 UT (1.745 days post-burst), respectively, both at a median airmass of 1.9. At 1.745 days post-burst, we detect a source consistent with both the UVOT position and the previously reported Legacy Survey source (Kuin et al. GCN 30975, Pozanenko et al. GCN 30972). Calibrated to SDSS, we measure a brightness of i_AB = 23.1 +/- 0.1 mag at seeing < 0.8'' for this source.

This is consistent with previously reported upper limits (Watson et al., GCN 30973, Hu et al. GCN 30976, Pozanenko et al. GCN 30972) and indicates significant fading from the i-band measurement reported by Kann et al. (GCN 30995) at 0.3091 days post-burst. At present, the source appears marginally extended, and it is very likely that the underlying host galaxy is contributing significantly to our measured flux (based on the expected i-band magnitude of the host from interpolating Legacy Survey DR9 photometry; Dey et al., 2019).

Further observations are planned to monitor the variability of the source. We thank Jennifer Andrews and additional Gemini staff for the rapid planning and execution of these observations.


GRB_name: GRB211023B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31003
SUBJECT: GRB 211023B: Mondy optical afterglow confirmation
DATE:    21/10/26 11:09:14 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

A. Pozanenko (IKI), S. Belkin (IKI),  E. Klunko (ISTP), N. Pankov (HSE), 
  report  on behalf of GRB IKI FuN:

We observed the field of GRB 211023B (Dichiara  et al., GCN  30960) with 
AZT-33IK telescope of Sayan observatory (Mondy)  starting on 2021-10-23 
(UT) 21:23:21.  We obtained 60 images in R-filter. We confirm afterglow 
of the GRB 211023B (Dichiara  et al., GCN  30960; Kuin et al. GCN 30975; 
Kann et al. GCN 30995; O'Connor et al., GCN 31000; Rastinejad et al., 
GCN 31002).   Preliminary photometry of the afterglow in stacked images 
is following

Date       UT start   t-T0       Filter Exp.   OT    Err.  UL(3sigma)
                     (mid, days)        (s)

2021-10-23 21:23:21  0.15613    R     15*60   20.46  0.31  20.5
2021-10-23 21:23:21  0.03297    R     60*60   20.97  0.40  20.9

The photometry is based on the nearby USNO-B1.0 stars
RA DEC R2
11:21:12.41280 +39:08:38.1120 15.33
11:21:05.20872 +39:04:33.9600 14.18

We note the obtained magnitudes are in agreement with  non-detections of 
the optical counterpart (Lipunov et al., GCN 30964; Pozanenko et al., 
GCN 30972; Watson et al., GCN 30973; Yu et al., GCN 30976).


GRB_name: GRB211023A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31004
SUBJECT: GRB 211023A: Mondy optical observations
DATE:    21/10/26 12:06:17 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), N. Pankov (HSE), 
  report  on behalf of GRB IKI FuN:

We observed the GRB 211023A (Fermi GBM team, GCN  30958) with AZT-33IK 
telescope of Sayan observatory (Mondy)  starting on 2021-10-25  (UT) 
15:16:32.  We obtained 17 images in R-filter. The afterglow   of the GRB 
211023A (Lipunov   et al., GCN  30977;  Kann  et al. GCN 30982; Hu et 
al. GCN 30990) is clearly detected.   Preliminary photometry of the 
afterglow in a stacked image is following

Date       UT start   t-T0       Filter Exp.   OT    Err.  UL(3sigma)
                     (mid, days)        (s)

2021-10-25 15:16:32  2.10265    R      17*120  19.87 0.15  21.0


The photometry is based on the nearby USNO-B1.0 stars
RA DEC R2
04:53:23.10336 +85:19:26.4720 14.09
04:52:47.26344 +85:22:52.1508 15.75

Based on photometry reported early (Kann  et al. GCN 30982; Hu et al. 
GCN 30990)  we can approximate a light curve of the afterglow as a power 
law with the index of 1.49+/-0.03. See also the figure of the light curve in

http://grb.rssi.ru/GRB211023A/GRB211023A_LC.png


GRB_name: GRB211024B
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31005
SUBJECT: GRB 211024B: Swift/UVOT detection
DATE:    21/10/26 13:13:02 GMT
FROM:    Paul Kuin at MSSL  <npkuin@gmail.com>

 N. P. M. Kuin (UCL-MSSL) and J. Gropp (PSU) reports on behalf of the
Swift/UVOT team:

We report here the early Swift/UVOT photometry of GRB 211024B (Gropp et
al.,
GCN Circ. 30980; Zhu et al. GCN Circ. 30984; Lien et al. GCN Circ 30989;
Evans et al. GCN Circ 30994; Kann et al. GCN Circ. 30995) at the position
reported by Zhu et al. (GCN Circ. 30984).


Preliminary detections using the UVOT photometric system
(Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) for the early exposures
are:

Filter         T_start(s)   T_stop(s)      Exp(s)           Mag

v                 6237       6437           197            19.2 +/- 0.4
v                12395      24343          1665            20.4 +/- 0.4
b                 5826       5927           197            20.0 +/- 0.4
u                 5621       5821           197            18.8 +/- 0.2
u                 6852       7052           197            19.3 +/- 0.3
w1                6647       6847           197            19.2 +/- 0.3
m2                6442       6642           197            19.3 +/- 0.3
w2                6032       6232           197            20.1 +/- 0.5
w2                7260       7360            98            19.5 +/- 0.5


The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening in the direction of the burst.


GRB_name: GRB211024A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31006
SUBJECT: GRB 211024A: Swift/BAT-GUANO detection and candidate arcminute localization of a short burst
DATE:    21/10/26 13:53:49 GMT
FROM:    Aaron Tohuvavohu at U Toronto  <aaron.tohu@gmail.com>

Aaron Tohuvavohu (U Toronto), James DeLaunay (UAlabama), Gayathri
Raman (PSU), Jamie A. Kennea (PSU), report:

Swift/BAT did not trigger on GRB 211024A (T0: 2021-10-24T01:34:11.4
UTC, Fermi/GBM trigger #  656732056, GCN 30962), also detected by
GECAM-B (GCN 30974).

The Fermi/GBM notice, distributed in near real-time, triggered the
Swift Mission Operations Center operated Gamma-ray Urgent Archiver for
Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1).

Upon trigger by this notice, GUANO sent a command to the Swift Burst
Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from
[-50,+150] seconds around the time of the burst. All the requested
event mode data was delivered to the ground.

The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu, in prep),
confidently detects the burst with a duration of ~0.1 seconds and
sqrt(TS) of 10.4.

A candidate localization is found with DeltaLLHOut of 13 and an
ambiguous DeltaLLHPeak of 2.5. For this reason we can confidently
claim detection, and some preference for an in-FOV origin, but the
best fit arcmin localization is not strongly preferred over other
positions.
Conventional imaging does not find a location for this burst.

The best BAT position is
RA, Dec = 28.053 -6.973 deg which is
   RA(J2000)  = 1h 52m 12.61s
   Dec(J2000) =  -6d 58â€² 23â€³
with an estimated uncertainty of 6 arcmin.

This position is consistent with the Fermi/GBM localization.

XRT and UVOT follow-up has been requested.
Results of follow-up observations will be reported in future circulars.

GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.

A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/


GRB_name: GRB211024A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31007
SUBJECT: GRB 211024A: Swift ToO observations
DATE:    21/10/26 15:12:57 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P. A. Evans (U. Leicester) reports on behalf of the Swift team:

Swift has initiated a ToO observation of the Swift/BAT GRB 211024A. 
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021464

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Swift/BAT event. Any X-ray source
considered to be a probable afterglow candidate will be reported via a 
GCN Circular after manual consideration.

Details of the XRT automated analysis methods are detailed in Evans et
al. (2007, A&A, 469, 379; 2009, MNRAS, 397, 1177 and 2014, ApJS, 210, 8).

This circular is an official product of the Swift-XRT team.


GRB_name: GRB211023A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31008
SUBJECT: GRB211023A: optical afterglow detection from Konkoly Observatory
DATE:    21/10/26 16:18:29 GMT
FROM:    Jozsef Vinko at Konkoly Observator  <vinko@konkoly.hu>

J. Vinko, A. Pal, L. Kriskovics, R. Szakats, K. Vida, Zs. Szabo
(Konkoly Observatory, Hungary) report:

We observed the field of GRB211023A (Fermi GBM team, GCN  30958)
with the RC80 robotic telescope at Piszkesteto Station of Konkoly
Observatory on 2021 Oct 25 starting at 17:46:47 UT. A series of 5x300 sec.
frames were collected through Sloan r'- and i' bands. The optical afterglow
(Zhirkov et al., GCN #30977;  Kann et al. GCN #30982; Hu et al. GCN #30990;
Belkin et al. GCN #31004)
was detected on the stacked frames with the following magnitudes, calibrated.
via nearby PS1 stars:

Date         UT-middle   t-T0(hr)  Exp(s)   r'(AB-mag)           i'(AB-mag)
2021-10-25   18:07:19    53.03     5x300    20.104 +/- 0.089  19.634 +/- 0.081

We measure the flux decline power-law index as -1.43 +/- 0.03, in accord with.
Belkin et al. (GCN #31004).


GRB_name: GRB211025A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31009
SUBJECT: GRB 211025A: Optical Afterglow Detection
DATE:    21/10/26 18:11:21 GMT
FROM:    Robert Strausbaugh at U. of the Virgin Islands  <robert.strausbaugh@uvi.edu>

R. Strausbaugh (U. of the Virgin Islands), A. Cucchiara (College of Marin) report on behalf of a larger collaboration:

We observed Swift GRB 211025A (Gropp, et al., GCN 30986) with the LCO 1-m Sinistro instrument at the McDonald Observatory, Texas, USA site, on October 25, from 11:27 to 11:49 UT (corresponding to 6.28 to 6.82 hours from the GRB trigger time) with the Bessel R and I filters.

We performed a series of 4x160s exposures in R and I bands. We detect a source consistent with the Swift UVOT detection coordinates (Oates, et al., GCN 30991) in R-band, but not in I-band. The following magnitudes and upper limits are calculated using the USNO-B.1 catalog as reference:

R=20.51+/-0.27
I>18.04

These magnitudes are not corrected for galactic extinction.

R.S. is funded by NSF AST grant #1831682


GRB_name: GRB211018A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31010
SUBJECT: GRB 211018A: Swift-XRT observations
DATE:    21/10/26 20:59:36 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

S. Dichiara (PSU), B. Sbarufatti (PSU), K.L. Page (U. Leicester), A.P.
Beardmore (U. Leicester), P. D'Avanzo (INAF-OAB), M.G. Bernardini
(INAF-OAB), E. Ambrosi (INAF-IASFPA) , D.N. Burrows (PSU), J. D. Gropp
(PSU) and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT
team:

Swift-XRT has performed follow-up observations of the
Fermi/LAT-detected burst GRB 211018A (Arimoto et al. GCN Circ. 30943),
collecting 4.4 ks of Photon Counting (PC) mode data between T0+304.3 ks
and T0+340.2 ks. 

Five uncatalogued X-ray sources have been detected, however none of
them is above the RASS limit or shows definitive signs of fading.
Therefore, at the present time we cannot identify which, if any, is the
afterglow. We notice that Source 2 and Source 4 are consistent with
catalogued quasars at redshift z = 0.64 and z=1.09, respectively. 
Details of these sources are given below:

Source 1:
  RA (J2000):  19.5986  =  01:18:23.66
  Dec (J2000): -3.6511  =  -03:39:04.1
  Error: 6.1 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (2.68 [+1.16, -0.92])e-3 ct s^-1  
  Distance: 338 arcsec from Fermi/LAT position.
  Flux: (9.3 [+4.0, -3.2])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 2:
  RA (J2000):  19.5656  =  01:18:15.74
  Dec (J2000): -3.3800  =  -03:22:48.2
  Error: 5.1 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (9.6 [+3.9, -3.1])e-3 ct s^-1   
  Distance: 884 arcsec from Fermi/LAT position.

Source 3:
  RA (J2000):  19.4544  =  01:17:49.06
  Dec (J2000): -3.6662  =  -03:39:58.4
  Error: 7.2 arcsec (radius, 90% conf.)
  Count-rate: (3.6 [+1.4, -1.1])e-3 ct s^-1   
  Distance: 835 arcsec from Fermi/LAT position.
  Flux: (1.85 [+0.70, -0.56])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)


Source 4:
  RA (J2000):  19.5576  =  01:18:13.83
  Dec (J2000): -3.7295  =  -03:43:46.2
  Error: 3.2 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: (6.6 +/- 1.6)e-3 ct s^-1  
  Distance: 636 arcsec from Fermi/LAT position.
  Flux: (1.70 +/- 0.40)e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 5:
  RA (J2000):  19.6548  =  01:18:37.16
  Dec (J2000): -3.6066  =  -03:36:23.9
  Error: 8.0 arcsec (radius, 90% conf.)
  Count-rate: (2.46 [+1.08, -0.85])e-3 ct s^-1  
  Distance: 84 arcsec from Fermi/LAT position.
  Flux: (5.3 [+2.3, -1.8])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
https://www.swift.ac.uk/ToO_GRBs/00021463.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB211024A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31011
SUBJECT: GRB 211024A: Fermi GBM detection
DATE:    21/10/26 22:38:14 GMT
FROM:    Suraj Poolakkil at UAH  <sp0076@uah.edu>

S. Poolakkil (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 01:34:11.40 UT on 24 October 2021, the Fermi Gamma-Ray Burst Monitor
(GBM)
triggered and located GRB 211024A (trigger 656732056 / 211024065)
which was also detected by the Swift/BAT-GUANO (Tohuvavohu et al. 2021, GCN
31006).
The GBM on-ground location is consistent with the Swift/BAT-GUANO position.

The angle from the Fermi LAT boresight at the GBM trigger time is 119
degrees.

The GBM light curve consists of a single emission episode
with a duration (T90) of about 0.06 s (50-300 keV).
The time-averaged spectrum from T0-0.128 s to T0+0.128 s
is best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.23 +/- 0.39  and
the cutoff energy, parameterized as Epeak, is 145 +/- 27 keV.

The event fluence (10-1000 keV) in this time interval is
(1.95 +/- 0.28)E-07 erg/cm^2. The 64-ms peak photon flux measured
starting from T0 s in the 10-1000 keV band
is 10.4 +/- 1.4 ph/s/cm^2.

The spectral analysis results presented above are preliminary;
final results will be published in the GBM GRB Catalog:
https://heasarc.gsfc.nasa.gov/W3Browse/fermi/fermigbrst.html

For Fermi GBM data and info, please visit the official Fermi GBM Support
Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB211027A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31012
SUBJECT: GRB 211027A: Fermi GBM Final Real-time Localization
DATE:    21/10/27 06:02:00 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely LONG GRB

At 05:51:52 UT on 27 Oct 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 211027A (trigger 657006717.695746 / 211027244).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 278.6, Dec = 19.0 (J2000 degrees, equivalent to J2000 18h 34m, 19d 00'), with a statistical uncertainty of 6.1 degrees.

The angle from the Fermi LAT boresight is 24.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211027244/quicklook/glg_skymap_all_bn211027244.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211027244/quicklook/glg_healpix_all_bn211027244.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211027244/quicklook/glg_lc_medres34_bn211027244.gif


GRB_name: GRB211024A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31013
SUBJECT: GRB 211024A: Swift-XRT observations
DATE:    21/10/27 06:33:32 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

M. Perri (SSDC & INAF-OAR), V. D'Elia (SSDC & INAF-OAR), A. D'Ai
(INAF-IASFPA), A. Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), D.N.
Burrows (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester)
and P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Swift/BAT-detected burst GRB 211024A (Aaron Tohuvavohu et al. GCN Circ.
31006), collecting 5.1 ks of Photon Counting (PC) mode data between
T0+221.8 ks and T0+234.5 ks. 

Four uncatalogued X-ray sources have been detected, however none of
them is above the RASS limit or shows definitive signs of fading.
Therefore, at the present time we cannot identify which, if any, is the
afterglow. Details of these sources are given below:

Source 3:
  RA (J2000):  27.9803  =  01:51:55.28
  Dec (J2000): -6.9611  =  -06:57:39.9
  Error: 9.0 arcsec (radius, 90% conf.)
  Count-rate: (1.24 [+0.76, -0.56])e-3 ct s^-1  
  Distance: 261 arcsec from Swift/BAT position.
  Flux: (4.0 [+2.4, -1.8])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 4:
  RA (J2000):  28.1958  =  01:52:47.00
  Dec (J2000): -7.0082  =  -07:00:29.4
  Error: 3.3 arcsec (radius, 90% conf. [Enhanced position])
  Count-rate: 0.0146 [+0.0032, -0.0029] ct s^-1   
  Distance: 527 arcsec from Swift/BAT position.
  Flux: (3.49 [+0.76, -0.70])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 5:
  RA (J2000):  27.8881  =  01:51:33.14
  Dec (J2000): -6.9512  =  -06:57:04.2
  Error: 6.8 arcsec (radius, 90% conf.)
  Count-rate: (1.21 [+0.83, -0.59])e-3 ct s^-1  
  Distance: 592 arcsec from Swift/BAT position.

Source 6:
  RA (J2000):  28.0277  =  01:52:6.65
  Dec (J2000): -7.0969  =  -07:05:48.8
  Error: 7.5 arcsec (radius, 90% conf.)
  Count-rate: (1.60 [+0.87, -0.66])e-3 ct s^-1  
  Distance: 454 arcsec from Swift/BAT position.

A catalogued source was also detected.

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
https://www.swift.ac.uk/ToO_GRBs/00021464.

This circular is an official product of the Swift-XRT team.


GRB_name: GRB211024A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31014
SUBJECT: GRB 211024A: Possible afterglow candidate from GIT
DATE:    21/10/27 11:35:56 GMT
FROM:    Harsh Kumar at Indian Inst of Tech,Bombay  <harshkosli13@gmail.com>

H. Kumar(IITB), V. Swain (IITB), U. Stanzin (IAO), V. Bhalerao(IITB), G. C.
Anupama(IIA), S. Barway(IIA) report on behalf of the GIT team:

We observed GRB 211024A detected by Fermi GBM (GCN 30962), localisation
further refined by Swift/BAT-GUANO

A. Tohuvavohu et al., (GCN #31006), with 0.7m GROWTH-India Telescope (GIT).
We obtained 2 exposures of 300 sec each in the r' filter, separated by ~15
min. We detected a potential candidate in our subtracted image at R.A.=
1:52:46.98 , DEC.= -7:00:27.30. This is coincident with an X-ray source
(#4) by Swift-XRT ToO observations (M. Perri et al. GCN # 31013). The
photometric results follow as:

-------------------------------------------------------------------

 JD (Start) | T_start-T0(days) | Filter | Magnitude (AB) |

-------------------------------------------------------------------

 2459514.2264 | 2.66 | r' | 19.83 +/- 0.038|

 2459514.2373 | 2.67 | r' | 19.87 +/- 0.046 |

-------------------------------------------------------------------
There was an underlying source at the position of the target in the raw
image which was subtracted using reference images from PanSTARRS. The
source magnitude is 17.86 mag in the r band with phot_z = 0.2108 +/- 0.02
(SDSS Release 12: Alam+, 2015). This may be the host galaxy of the GRB.
There is no minor planet at the location of the candidate in MPC. The gap
between exposures was not sufficient to measure any decay. Further
observations are planned. Follow-up observations for this source are
strongly encouraged.

The magnitudes are calibrated against PanSTARRS (Flewelling et al., 2018)
and not corrected for Galactic extinction.

The GROWTH India Telescope (GIT) is a 70-cm telescope with a 0.7-degree
field of view, set up by the Indian Institute of Astrophysics (IIA) and the
Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and
IUSSTF. It is located at the Indian Astronomical Observatory (Hanle),
operated by IIA. We acknowledge funding by the IITB alumni batch of 1994,
which partially supports operations of the telescope. Telescope technical
details are available at https://sites.google.com/view/growthindia/.


GRB_name: GRB211027A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31015
SUBJECT: Fermi GRB 211027A: Global MASTER-Net observations report 
DATE:    21/10/27 14:30:18 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, 
D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, T.Pogrosheva, E.Minkina,
A.Chasovnikov, V.Topolev, V.Grinshpun, D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

A. Gabovich, V.Yurkov 
(Blagoveschensk Educational State University)


MASTER-Tunka robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Applied Physics Institute, Irkutsk State University) started inspect of the Fermi GRB 211027A ( Fermi GBM team, GCN 31012) errorbox  20879 sec after notice time and 20909 sec after trigger time at 2021-10-27 11:40:21 UT, with upper limit up to  18.0 mag. The observations began at zenith distance = 40 deg. The sun  altitude  is -17.7 deg. 

The galactic latitude b = 12 deg., longitude l = 48 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1767399

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

   20939 | 2021-10-27 11:40:21 |        MASTER-Tunka | (18h 36m 12.97s , +21d 29m 21.2s) |   C |    60 | 17.8 |        
   21118 | 2021-10-27 11:43:20 |        MASTER-Tunka | (18h 45m 24.29s , +18d 22m 36.6s) |   C |    60 | 16.9 |  Coadd 
   21186 | 2021-10-27 11:44:28 |        MASTER-Tunka | (18h 29m 19.97s , +18d 24m 29.9s) |   C |    60 | 17.6 |  Coadd 
   21186 | 2021-10-27 11:44:28 |        MASTER-Tunka | (18h 27m 33.61s , +19d 36m 05.7s) |   C |    60 | 17.9 |  Coadd 
   21420 | 2021-10-27 11:48:22 |        MASTER-Tunka | (18h 24m 11.62s , +21d 29m 09.0s) |   C |    60 | 16.6 |  Coadd 
   21492 | 2021-10-27 11:49:34 |        MASTER-Tunka | (18h 49m 34.73s , +16d 30m 18.6s) |   C |    60 | 16.2 |  Coadd 
   21565 | 2021-10-27 11:50:47 |        MASTER-Tunka | (18h 23m 53.87s , +22d 11m 32.4s) |   C |    60 | 16.6 |  Coadd 
   21637 | 2021-10-27 11:51:59 |        MASTER-Tunka | (18h 39m 17.95s , +14d 34m 17.0s) |   C |    60 | 17.0 |  Coadd 
   21710 | 2021-10-27 11:53:12 |        MASTER-Tunka | (18h 39m 32.42s , +24d 04m 40.4s) |   C |    60 | 17.6 |  Coadd 
   21710 | 2021-10-27 11:53:12 |        MASTER-Tunka | (18h 37m 44.64s , +25d 15m 57.9s) |   C |    60 | 18.0 |  Coadd 
   21918 | 2021-10-27 11:56:41 |        MASTER-Tunka | (18h 38m 00.98s , +20d 18m 12.5s) |   C |    60 | 16.8 |  Coadd 
   21919 | 2021-10-27 11:56:41 |        MASTER-Tunka | (18h 36m 14.32s , +21d 29m 31.3s) |   C |    60 | 16.9 |  Coadd 
   21987 | 2021-10-27 11:57:49 |        MASTER-Tunka | (18h 46m 24.98s , +20d 17m 10.7s) |   C |    60 | 17.0 |  Coadd 
   21987 | 2021-10-27 11:57:49 |        MASTER-Tunka | (18h 43m 32.47s , +19d 35m 27.7s) |   C |    60 | 16.8 |  Coadd 
   22214 | 2021-10-27 12:01:36 |        MASTER-Tunka | (19h 01m 17.87s , +18d 21m 56.9s) |   C |    60 | 16.5 |  Coadd 
   22214 | 2021-10-27 12:01:36 |        MASTER-Tunka | (18h 59m 32.63s , +19d 33m 15.7s) |   C |    60 | 16.8 |  Coadd 
   22286 | 2021-10-27 12:02:49 |        MASTER-Tunka | (18h 40m 18.67s , +22d 10m 29.4s) |   C |    60 | 16.4 |  Coadd 
   22576 | 2021-10-27 12:07:38 |        MASTER-Tunka | (18h 23m 48.64s , +22d 11m 05.2s) |   C |    60 | 16.7 |  Coadd 
   22779 | 2021-10-27 12:11:02 |        MASTER-Tunka | (18h 58m 22.62s , +20d 15m 45.8s) |   C |    60 | 17.3 |  Coadd 
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.


GRB_name: GRB211023B
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31016
SUBJECT: GRB 211023B: NUTTelA-TAO / BSTI Early Optical Limits (Preliminary)
DATE:    21/10/28 01:28:54 GMT
FROM:    Bruce Grossan at LBNL/UCB SSL  <Bruce_Grossan@lbl.gov>

B. Grossan (UCB, NU), T. Komesh (NU), Z. Maksut (NU), M. Krugov (FAI),  E. Linder (UCB, NU), E. Abdikamalov (NU), G. F. Smoot (HKUST, UCB, NU), report on behalf of the Energetic Cosmos Laboratory:

The Nazarbayev University Transient Telescope at Assy-Turgen Astrophysical Observatory (NUTTelA-TAO) observed the field of GRB 211023B soon after receipt an automated GCN / BAT position alert, observing in Sloan g', r' and i' bands, with the Burst Simultaneous Three-Channel Imager (BSTI; Grossan, Kumar & Smoot 2019, JHEA, 32, 14).

We started observations at 21:26:33 UT on 2021-10-23, 1241 s after the BAT trigger. Observations were made partly cloudy conditions starting at only about 18 deg. target altitude. No source consistent with the XRT (P. Evans et al., GCN Circ. 30966) or UVOT position (S. Dichiara; GCN Circ. 30960) was detected.  Note that these observations provide essentially full-time coverage, simultaneous in all three bands. We report the following results:

start time    t-t0(s)  end time        UL g'    UL r'    ULi'       exposure_time (s)
------------    --------  ------------        ------    ------     ------      --------------------
21:26:33     1241   21:27:33        17.6    18.7      17.8           60
21:27:56     1324   22:47:56        18.5    19.5      18.7         300

start time is in UT. t-t0(s) gives the time since trigger, in seconds. UL g', r', i', gives the 5 sigma upper limit sensitivity in magnitudes in the respective filter, for images co-added to the given exposure time. The first row in the table corresponds to co-adds of an initial short exposure image sequence of 7.5 s for g' and i', and 0.3 s for r' (these sub-second exposures are read-noise suppressed by our EMCCD cameras, with high gain electron multiplication active; other images are taken in conventional CCD operation mode). The second row corresponds to co-adds from a continuing series of 15 s exposures for g' and i', and 3 s for r', uninterrupted for the 80 minutes.  Calibration was done with the 2-5 bright Pan-STARRS catalog stars on our images.

We caution the reader that these are preliminary results, without color or other corrections. Please also note that times are approximate.
----------------------------------
NU = Nazarbayev University, Nur-Sultan, Kazakhstan
UCB = University of California, Berkeley, USA
HKUST = Hong Kong University of Science and Technology
FAI = Fesenkov Astrophysical Institute, Kazakhstan

The NUTTelA-TAO Team acknowledges the support of the staff of the Assy-Turgen Astrophysical Observatory, Almaty, Kazakhstan, and the Fesenkov Astrophysical Institute, Almaty, Kazkhstan.


GRB_name: GRB211024A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31017
SUBJECT: GRB 211024A: Swift-XRT source 4 is not an afterglow.
DATE:    21/10/28 12:09:28 GMT
FROM:    Harsh Kumar at Indian Inst of Tech,Bombay  <harshkosli13@gmail.com>

H. Kumar(IITB), S. Joharle (IITB), J. Stanzin (IAO), V. Bhalerao(IITB), G.
C. Anupama(IIA), S. Barway(IIA) report on behalf of the GIT team:

We continued the observation of X-ray source (#4) by Swift-XRT ToO
observations (M. Perri et al. GCN # 31013), a candidate for the afterglow
of Fermi GBM GRB 211024A (GCN 30962), A. Tohuvavohu et al., (GCN #31006),
with 0.7m GROWTH-India Telescope (GIT). We obtained multiple exposures of
300 sec each in the g', r' and i' filters. The photometric results follow
as:

-------------------------------------------------------------------

 JD (Start) | T_start-T0(days) | Filter | Magnitude (AB) |

-------------------------------------------------------------------

 2459515.167376 | 3.60 |  g' |  20.25 +/- 0.06

 2459515.136124 | 3.57 |  i' |  19.68 +/- 0.057

 2459515.146851 | 3.58 |  r' |  19.85 +/- 0.034

-------------------------------------------------------------------
Comparing magnitude in r' filter with our previous photometry reported in
H. Kumar et al., (GCN #31014), we conclude that the source is not evolving
and is not an afterglow of the GRB 211024A.

We did not detect sources #3,#5,#6 of Swift-XRT ToO observations (M. Perri
et al. GCN # 31013) up to the following upper limits:-

-------------------------------------------------------------------

 JD (Start) | T_start-T0(days) | Filter | upper limit |

-------------------------------------------------------------------

 2459514.2374 | 2.67 | r' | > 20.26

 2459515.1674 | 3.60 | g' | > 21.03

 2459515.1361 | 3.58 | i' | > 20.51

 -------------------------------------------------------------------

The magnitudes are calibrated against PanSTARRS (Flewelling et al., 2018)
and not corrected for Galactic extinction.

The GROWTH India Telescope (GIT) is a 70-cm telescope with a 0.7-degree
field of view, set up by the Indian Institute of Astrophysics (IIA) and the
Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and
IUSSTF. It is located at the Indian Astronomical Observatory (Hanle),
operated by IIA. We acknowledge funding by the IITB alumni batch of 1994,
which partially supports operations of the telescope. Telescope technical
details are available at https://sites.google.com/view/growthindia/.


GRB_name: GRB211023A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31018
SUBJECT: GRB 211023A: continued Mondy optical observations
DATE:    21/10/28 13:05:00 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI), A. Pozanenko (IKI), E. Klunko (ISTP), N. Pankov (HSE), 
  report  on behalf of GRB IKI FuN:

We observed the GRB 211023A (Fermi GBM team, GCN  30958) with AZT-33IK 
telescope of Sayan observatory (Mondy)  starting on 2021-10-26  (UT) 
14:47:57.  We obtained 17 images in R-filter. The afterglow   of the GRB 
211023A (Lipunov   et al., GCN  30977;  Kann  et al. GCN 30982; Hu et 
al. GCN 30990; Belkin et al., GCN 31004) is clearly detected. 
Preliminary photometry of the afterglow in a stacked image is following

Date       UT start   t-T0       Filter Exp.   OT    Err.  UL(3sigma)
                     (mid, days)        (s)

2021-10-26 14:47:57  3.09182    R      30*120  20.57 0.06  22.7


The photometry is based on the nearby USNO-B1.0 stars
RA DEC R2
04:53:23.10336 +85:19:26.4720 14.09
04:52:47.26344 +85:22:52.1508 15.75


GRB_name: GRB211023A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31020
SUBJECT: GRB 211023A: Terskol optical observations
DATE:    21/10/28 18:01:05 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI, HSE), I. Sokolov (INASAN, KIAM), D. Berezin (IC AMER 
NASU), A. Pozanenko (IKI),  N. Pankov (IKI, HSE), G. Butenko (IC AMER 
NASU)  report on behalf of GRB IKI FuN:

We observed the GRB 211023A (Fermi GBM team, GCN 30958) with Zeiss-2000 
   telescope and Zeiss-600  telescope of Terskol observatory.  The 
afterglow  of the GRB 211023A (Lipunov   et al., GCN  30977;  Kann  et 
al. GCN 30982; Hu et al. GCN 30990; Belkin et al., GCN 31004,31018) is 
clearly detected with Zeiss-2000  and marginally detected with 
Zeiss-600.  Preliminary photometry of the afterglow is following.

Date       UT start  t-T0     Filter Exp.  OT   Err. UL.  Telescope
                      (mid, days)      (s)


2021-10-26 15:08:26  3.11542   R  29*180  20.59 0.16 21.8 Zeiss-2000
2021-10-28 01:06:22  4.51191   R  11*180  20.91 0.10 22.5 Zeiss-2000
2021-10-28 00:15:55  4.47895   R  39*60   20.80 0.40 20.7 Zeiss-600

The photometry is based on the nearby USNO-B1.0 stars
RA DEC R2
04:53:23.10336 +85:19:26.4720 14.09
04:52:47.26344 +85:22:52.1508 15.75

The updated light curve can be found in

http://grb.rssi.ru/GRB211023A/GRB211023A_LC.png


GRB_name: GRB211023B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31021
SUBJECT: GRB 2121023B: 6 GHz VLA radio upper limit
DATE:    21/10/28 19:26:20 GMT
FROM:    Genevieve Schroeder at Northwestern University  <genevieveschroeder2023@u.northwestern.edu>

G. Schroeder, W. Fong, A. Rouco Escorial, (Northwestern), T. Laskar (Univ.
Radboud), E. Berger (Harvard) report:

"We observed the position of GRB 211023B (Dichiara et al. GCN 30960) with
the Karl G. Jansky Very Large Array (VLA) under program 21B-198 (PI: Fong)
beginning on 2021 October 27.51 UT (3.63 days post-burst) at a mean
frequency of 6 GHz.

Based on preliminary analysis, in 1 hour of observations we do not detect
any radio emission at or near the position of the optical afterglow and
host (Kuin et al. GCN 30975; Pozanenko et al. GCN 30972; Kann et al. GCN
30995; O'Connor et al., GCN 31000; Rastinejad et al., GCN 31002; Pozanenko
et al., GCN 31003) to a 3-sigma limit of 13 microJy. We also do not detect
any source within the XRT position (Beardmore et al. GCN 30966).
Additional, detailed analysis is ongoing.

We thank the VLA staff for quickly approving and executing these
observations."


GRB_name: GRB211023A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31022
SUBJECT: Konus-Wind detection of GRB 211023A
DATE:    21/10/28 21:24:26 GMT
FROM:    Anna Ridnaia at Ioffe Institute  <ridnaia@mail.ioffe.ru>

A. Ridnaia, D. Frederiks, S. Golenetskii, A. Lysenko,
D. Svinkin, A. Tsvetkova,  M. Ulanov, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration GRB 211023A (Fermi-GBM detection:
Fermi GBM Team, GCN 30958; Lesage et al., GCN 30965;
Fermi-LAT detection: Di Lalla et al., GCN 30961;
AGILE detection: Ursi et al., GCN 30969)
triggered Konus-Wind at T0=47199.142 s UT (13:06:39.142).

The burst light curve shows a multipeaked structure
started at ~T0-65.3 s with a total duration of ~207.9 s.
The emission is seen up to ~6 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB211023_T47199/

As observed by Konus-Wind, the burst
had a fluence of 1.13(-0.04,+0.05)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+6.368 s,
of 5.12(-1.01,+1.01)x10^-6 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+103.936 s)
is best fit in the 20 keV - 6 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -1.85(-0.03,+0.03)
and Ep = 122(-12,+15) keV (chi2 = 100/79 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.4
(chi2 = 99/78).

The spectrum near the maximum count rate
(measured from T0+5.888 to T0+10.496 s)
is best fit in the 20 keV - 6 MeV range
by a power law with exponential cutoff model
with  alpha = -1.27(-0.06,+0.06)
and Ep = 267(-22,+27) keV (chi2 = 76/72 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.6
(chi2 = 75/71).

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB211023A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31023
SUBJECT: GRB 211023A: 1.3m DFOT Optical Observations
DATE:    21/10/30 07:13:38 GMT
FROM:    Rahul Gupta at ARIES, India  <rahulbhu.c157@gmail.com>

[image: image.gif]Amit Kumar, Rahul Gupta, Amit Ror, Dimple, Ankur Ghosh, Arpan
Ghosh, Amar Aryan, Brajesh Kumar, S. B. Pandey, and Kuntal Misra (ARIES)
report:


We observed the Fermi GBM and LAT detected GRB 211023A (Fermi GBM
Team, GCN 30958; Lesage et al. 2021, GCN 30965; and N. Di Lalla et al.
2021, GCN 30961) with 1.3m Devasthal Fast Optical Telescope (DFOT)
located at Devasthal observatory of Aryabhatta Research Institute of
Observational Sciences (ARIES), India. The observations were started
on 2021-10-28 at 19:22:54 UT, i.e., ~ 5.26 days after the Fermi
trigger. We have taken multiple frames having an exposure time of 300
sec in the R filter. We clearly detected the optical afterglow of GRB
211023A (Lipunov et al. 2021, GCN 30970; Zhirkov et al. 2021, GCN
30977; Kann et al. 2021, GCN 30982; Hu et al. 2021, GCN 30990; Belkin
et al. 2021, GCN 31004, 31018, 31020; and Vinko et al. 2021, GCN
31008) in our stacked image. The preliminary photometric estimate of
the afterglow is the following :

Date Start UT   T-T0 (mid, days) Filter  Exp time (sec)   Magnitude

=========================================================
2021-10-28 19:22:54   ~5.28       R           300*15          21.37 +/- 0.08


Further observations are requested with 1.3m DFOT.The magnitude is not
corrected for the Galactic extinction in the direction of the burst.
Photometric calibration is performed using the standard stars from the
USNO-B1.0 catalog.

This circular may be cited.


GRB_name: GRB211022A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31024
SUBJECT: IPN triangulation of GRB 211022A
DATE:    21/10/30 12:36:29 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

A.S. Kozyrev, D.V. Golovin, M.L. Litvak, I.G. Mitrofanov, and A.B. Sanin
on behalf of the MGNS/BepiColombo and HEND/Mars Odyssey teams,

J. Benkhoff on behalf of the BepiColombo team,

K. Hurley on behalf of the IPN,

D. Svinkin, S. Golenetskii, D. Frederiks, A. Ridnaia,
A. Lysenko, and T. Cline on behalf of the Konus-Wind team,

A. von Kienlin, X. Zhang, A. Rau, V. Savchenko, E. Bozzo,
and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

S. Barthelmy, J. Cummings, H. Krimm, D. Palmer, and A. Tohuvavohu
on behalf of the Swift-BAT team, and

W. Boynton, C. Fellows, K. Harshman, H. Enos, and R. Starr,
on behalf of the GRS-Odyssey GRB team, report:

The long-duration GRB 211022A
(GECAM-B detection: Zhao et al., GCN Circ. 30955;
AstroSat-CZTI detection: Prasad et al., GCN Circ. 30968)
was detected by BepiColombo (MGNS; see introductory GCN Circ. 30949),
Mars-Odyssey (HEND), GECAM-B, AstroSat (CZTI), Konus-Wind,
INTEGRAL (SPI-ACS), and Swift (BAT), at about 2845 s UT (00:47:25).
The burst was outside the coded field of view of the BAT.

The burst light curves in the energy range 30 keV-1.5 MeV (HEND)
and 250-450 keV (MGNS) exhibit a multi-peaked pulse structure
with a total duration of ~150 s.

We have triangulated GRB 211022A to the following 3 sigma annuli:
------------------------------------------------------------
            R.A.(J2000)  Dec.(J2000)    R      +dR     -dR
                deg         deg        deg     deg     deg
------------------------------------------------------------
MGNS-HEND      30.161     12.392    125.005  +0.096  -0.214
SPI-ACS-HEND  202.386     -8.806     53.850  +0.093  -0.071
Konus-SPI-ACS 193.415    -14.239     44.866  +5.706  -5.232
------------------------------------------------------------
The MGNS-HEND and SPI-ACS-HEND annuli intersect to form two error
boxes one of which is inconsistent with the Konus-SPI-ACS annulus,
the KW ecliptic latitude response, and the GECAM position.

The correct preliminary, 3 sigma error box is:
---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   161.615 (10h 46m 27s) -51.006 (-51d 00' 21")
  Corners:
   160.852 (10h 43m 24s) -50.508 (-50d 30' 29")
   162.525 (10h 50m 06s) -51.893 (-51d 53' 33")
   161.845 (10h 47m 23s) -51.080 (-51d 04' 47")
   160.242 (10h 40m 58s) -49.672 (-49d 40' 19")
  ---------------------------------------------
The error box area is 1026 sq. arcmin, and its maximum
dimension is 2.6 deg (the minimum one is 9.8 arcmin).
The Sun distance was 54 deg.

This box may be improved.

A triangulation maps are posted at:
http://www.ioffe.ru/LEA/GRBs/GRB211022_T02845/IPN

The Konus-Wind time history and spectrum will be given
in a forthcoming GCN Circular.


GRB_name: GRB211031A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31025
SUBJECT: GRB 211031A: Fermi GBM Final Real-time Localization
DATE:    21/10/31 04:21:52 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM  <do_not_reply@GIOC.nsstc.nasa.gov>

The Fermi GBM team reports the detection of a likely SHORT GRB

At 04:11:39 UT on 31 Oct 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 211031A (trigger 657346304.154694 / 211031175).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 72.0, Dec = -54.3 (J2000 degrees, equivalent to J2000 04h 47m, -54d 17'), with a statistical uncertainty of 10.7 degrees.

The angle from the Fermi LAT boresight is 28.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211031175/quicklook/glg_skymap_all_bn211031175.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211031175/quicklook/glg_healpix_all_bn211031175.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn211031175/quicklook/glg_lc_medres34_bn211031175.gif


GRB_name: GRB211031A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  31026
SUBJECT: Fermi GRB 211031A: Global MASTER-Net observations report 
DATE:    21/10/31 06:00:24 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, 
D. Vlasenko, G.Antipov, D.Zimnukhov, V.Senik, T.Pogrosheva, E.Minkina,
A.Chasovnikov, V.Topolev, V.Grinshpun, D.Kuvshinov,  D. Cheryasov
(Lomonosov Moscow State University, SAI, Physics Department),

R. Podesta, C.Lopez, F. Podesta, C.Francile 
(Observatorio Astronomico Felix Aguilar OAFA),

R. Rebolo, M. Serra 
(The Instituto de Astrofisica de Canarias),

D. Buckley 
(South African Astronomical Observatory),

O.A. Gres, N.M. Budnev
(Irkutsk State University, API),

A. Tlatov, D. Dormidontov 
(Kislovodsk Solar Station of the Pulkovo Observatory),

A. Gabovich, V.Yurkov 
(Blagoveschensk Educational State University)


MASTER-IAC robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Spain (IAC Teide Observatory) started inspect of the Fermi GRB 211031A ( Fermi GBM team, GCN 31025) errorbox  236 sec after notice time and 247 sec after trigger time at 2021-10-31 04:15:47 UT, with upper limit up to  18.0 mag. The observations began at zenith distance = 80 deg. The sun  altitude  is -39.6 deg. 

The galactic latitude b = -39 deg., longitude l = 262 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1770974

We obtain a following upper limits.  

Tmid-T0  |      Date Time      |          Site       |             Coord (J2000)          |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________

     278 | 2021-10-31 04:15:47 |          MASTER-IAC | (04h 36m 44.84s , -50d 06m 53.9s) |   C |    60 | 17.8 |        
     278 | 2021-10-31 04:15:47 |          MASTER-IAC | (04h 49m 15.87s , -50d 12m 15.5s) |   C |    60 | 17.5 |        
     359 | 2021-10-31 04:17:08 |          MASTER-IAC | (04h 26m 14.58s , -48d 14m 56.9s) |   C |    60 | 17.8 |        
     359 | 2021-10-31 04:17:08 |          MASTER-IAC | (04h 38m 17.79s , -48d 20m 19.1s) |   C |    60 | 17.6 |        
     439 | 2021-10-31 04:18:28 |          MASTER-IAC | (04h 38m 51.68s , -46d 19m 12.6s) |   C |    60 | 17.7 |        
     439 | 2021-10-31 04:18:28 |          MASTER-IAC | (04h 50m 28.92s , -46d 24m 36.8s) |   C |    60 | 17.8 |        
     519 | 2021-10-31 04:19:48 |          MASTER-IAC | (04h 49m 00.94s , -48d 13m 25.2s) |   C |    60 | 17.7 |        
     519 | 2021-10-31 04:19:48 |          MASTER-IAC | (05h 01m 03.51s , -48d 18m 49.0s) |   C |    60 | 17.9 |        
     599 | 2021-10-31 04:21:08 |          MASTER-IAC | (04h 16m 44.59s , -46d 19m 34.7s) |   C |    60 | 17.6 |        
     599 | 2021-10-31 04:21:08 |          MASTER-IAC | (04h 28m 21.86s , -46d 24m 56.7s) |   C |    60 | 17.7 |        
     679 | 2021-10-31 04:22:28 |          MASTER-IAC | (04h 03m 27.30s , -48d 15m 04.6s) |   C |    60 | 17.6 |        
     679 | 2021-10-31 04:22:28 |          MASTER-IAC | (04h 15m 30.53s , -48d 20m 21.6s) |   C |    60 | 17.6 |        
     759 | 2021-10-31 04:23:47 |          MASTER-IAC | (04h 29m 28.64s , -44d 27m 11.9s) |   C |    60 | 18.0 |        
     759 | 2021-10-31 04:23:47 |          MASTER-IAC | (04h 40m 43.23s , -44d 32m 34.3s) |   C |    60 | 17.9 |        
     840 | 2021-10-31 04:25:08 |          MASTER-IAC | (05h 00m 31.12s , -50d 07m 51.8s) |   C |    60 | 17.7 |        
     840 | 2021-10-31 04:25:08 |          MASTER-IAC | (05h 13m 01.95s , -50d 13m 14.2s) |   C |    60 | 17.7 |        
     919 | 2021-10-31 04:26:28 |          MASTER-IAC | (05h 24m 10.95s , -50d 05m 36.3s) |   C |    60 | 17.6 |        
     919 | 2021-10-31 04:26:28 |          MASTER-IAC | (05h 36m 41.14s , -50d 11m 01.0s) |   C |    60 | 17.6 |        
    1008 | 2021-10-31 04:27:57 |          MASTER-IAC | (05h 00m 49.49s , -46d 19m 38.2s) |   C |    60 | 18.0 |        
    1008 | 2021-10-31 04:27:57 |          MASTER-IAC | (05h 12m 26.75s , -46d 25m 02.2s) |   C |    60 | 18.0 |        
    1088 | 2021-10-31 04:29:16 |          MASTER-IAC | (05h 11m 56.16s , -48d 12m 07.2s) |   C |    60 | 17.9 |        
    1088 | 2021-10-31 04:29:16 |          MASTER-IAC | (05h 23m 58.44s , -48d 17m 31.6s) |   C |    60 | 17.7 |        
    1168 | 2021-10-31 04:30:36 |          MASTER-IAC | (04h 50m 46.76s , -44d 25m 30.0s) |   C |    60 | 18.0 |        
    1168 | 2021-10-31 04:30:36 |          MASTER-IAC | (05h 02m 01.22s , -44d 30m 54.5s) |   C |    60 | 18.0 |        
    1248 | 2021-10-31 04:31:56 |          MASTER-IAC | (04h 49m 12.23s , -50d 12m 20.3s) |   C |    60 | 17.5 |        
    1248 | 2021-10-31 04:31:56 |          MASTER-IAC | (04h 36m 41.20s , -50d 07m 02.1s) |   C |    60 | 17.5 |        
    1328 | 2021-10-31 04:33:17 |          MASTER-IAC | (04h 26m 15.80s , -48d 14m 22.8s) |   C |    60 | 17.6 |        
    1328 | 2021-10-31 04:33:17 |          MASTER-IAC | (04h 38m 19.02s , -48d 19m 41.8s) |   C |    60 | 17.6 |        
    1410 | 2021-10-31 04:34:39 |          MASTER-IAC | (04h 38m 45.08s , -46d 20m 58.0s) |   C |    60 | 17.7 |        
    1410 | 2021-10-31 04:34:39 |          MASTER-IAC | (04h 50m 22.92s , -46d 26m 18.5s) |   C |    60 | 17.7 |        
    1490 | 2021-10-31 04:35:59 |          MASTER-IAC | (04h 49m 05.79s , -48d 14m 28.4s) |   C |    60 | 17.8 |        
    1490 | 2021-10-31 04:35:59 |          MASTER-IAC | (05h 01m 08.89s , -48d 19m 48.0s) |   C |    60 | 17.8 |        
    1570 | 2021-10-31 04:37:19 |          MASTER-IAC | (04h 16m 45.94s , -46d 19m 45.9s) |   C |    60 | 17.6 |        
    1570 | 2021-10-31 04:37:19 |          MASTER-IAC | (04h 28m 23.52s , -46d 25m 03.9s) |   C |    60 | 17.6 |        
    1650 | 2021-10-31 04:38:39 |          MASTER-IAC | (04h 15m 26.64s , -48d 21m 01.4s) |   C |    60 | 17.5 |        
    1650 | 2021-10-31 04:38:39 |          MASTER-IAC | (04h 03m 22.80s , -48d 15m 51.1s) |   C |    60 | 17.5 |        
    1730 | 2021-10-31 04:39:59 |          MASTER-IAC | (04h 29m 32.96s , -44d 25m 44.0s) |   C |    60 | 17.8 |        
    1730 | 2021-10-31 04:39:59 |          MASTER-IAC | (04h 40m 47.25s , -44d 31m 03.2s) |   C |    60 | 17.8 |        
    1810 | 2021-10-31 04:41:19 |          MASTER-IAC | (05h 00m 23.71s , -50d 07m 16.7s) |   C |    60 | 17.5 |        
    1810 | 2021-10-31 04:41:19 |          MASTER-IAC | (05h 12m 54.26s , -50d 12m 34.3s) |   C |    60 | 17.5 |        
    1890 | 2021-10-31 04:42:39 |          MASTER-IAC | (05h 24m 06.92s , -50d 05m 25.6s) |   C |    60 | 17.6 |        
    1890 | 2021-10-31 04:42:39 |          MASTER-IAC | (05h 36m 36.72s , -50d 10m 45.6s) |   C |    60 | 17.5 |        
    1980 | 2021-10-31 04:44:09 |          MASTER-IAC | (05h 00m 52.27s , -46d 19m 17.1s) |   C |    60 | 17.9 |        
    1980 | 2021-10-31 04:44:09 |          MASTER-IAC | (05h 12m 29.05s , -46d 24m 36.9s) |   C |    60 | 17.9 |        
    2060 | 2021-10-31 04:45:29 |          MASTER-IAC | (05h 11m 51.07s , -48d 13m 54.2s) |   C |    60 | 17.8 |        
    2060 | 2021-10-31 04:45:29 |          MASTER-IAC | (05h 23m 53.40s , -48d 19m 13.7s) |   C |    60 | 17.7 |        
    2140 | 2021-10-31 04:46:49 |          MASTER-IAC | (04h 50m 52.07s , -44d 26m 38.8s) |   C |    60 | 17.9 |        
    2140 | 2021-10-31 04:46:49 |          MASTER-IAC | (05h 02m 06.28s , -44d 31m 58.6s) |   C |    60 | 17.9 |        
    2247 | 2021-10-31 04:48:36 |          MASTER-IAC | (04h 26m 13.29s , -48d 15m 24.6s) |   C |    60 | 17.5 |        
    2247 | 2021-10-31 04:48:36 |          MASTER-IAC | (04h 38m 16.50s , -48d 20m 37.5s) |   C |    60 | 17.5 |        
    2327 | 2021-10-31 04:49:56 |          MASTER-IAC | (04h 38m 50.29s , -46d 19m 33.6s) |   C |    60 | 17.6 |        
    2327 | 2021-10-31 04:49:56 |          MASTER-IAC | (04h 50m 27.51s , -46d 24m 51.2s) |   C |    60 | 17.7 |        
    2407 | 2021-10-31 04:51:16 |          MASTER-IAC | (04h 48m 59.87s , -48d 13m 44.4s) |   C |    60 | 17.6 |        
    2407 | 2021-10-31 04:51:16 |          MASTER-IAC | (05h 01m 02.62s , -48d 19m 01.4s) |   C |    60 | 17.7 |        
    2487 | 2021-10-31 04:52:36 |          MASTER-IAC | (04h 16m 41.85s , -46d 19m 52.3s) |   C |    60 | 17.3 |        
    2487 | 2021-10-31 04:52:36 |          MASTER-IAC | (04h 28m 19.42s , -46d 25m 06.4s) |   C |    60 | 17.5 |        
    2567 | 2021-10-31 04:53:56 |          MASTER-IAC | (04h 03m 25.63s , -48d 15m 26.4s) |   C |    60 | 17.0 |        
    2567 | 2021-10-31 04:53:56 |          MASTER-IAC | (04h 15m 29.73s , -48d 20m 30.0s) |   C |    60 | 17.1 |        
    2647 | 2021-10-31 04:55:15 |          MASTER-IAC | (04h 29m 26.64s , -44d 27m 24.5s) |   C |    60 | 17.6 |        
    2647 | 2021-10-31 04:55:15 |          MASTER-IAC | (04h 40m 41.23s , -44d 32m 42.7s) |   C |    60 | 17.7 |        
    2727 | 2021-10-31 04:56:35 |          MASTER-IAC | (05h 00m 30.09s , -50d 08m 04.0s) |   C |    60 | 17.4 |        
    2727 | 2021-10-31 04:56:35 |          MASTER-IAC | (05h 13m 00.88s , -50d 13m 20.3s) |   C |    60 | 17.4 |        
    2807 | 2021-10-31 04:57:55 |          MASTER-IAC | (05h 24m 10.11s , -50d 05m 55.1s) |   C |    60 | 17.4 |        
    2807 | 2021-10-31 04:57:55 |          MASTER-IAC | (05h 36m 40.10s , -50d 11m 14.1s) |   C |    60 | 17.5 |        
    2887 | 2021-10-31 04:59:15 |          MASTER-IAC | (05h 00m 48.67s , -46d 20m 15.2s) |   C |    60 | 17.7 |        
    2887 | 2021-10-31 04:59:15 |          MASTER-IAC | (05h 12m 25.67s , -46d 25m 36.0s) |   C |    60 | 17.8 |        
    2967 | 2021-10-31 05:00:35 |          MASTER-IAC | (05h 11m 55.69s , -48d 12m 17.8s) |   C |    60 | 17.7 |        
    2967 | 2021-10-31 05:00:35 |          MASTER-IAC | (05h 23m 57.70s , -48d 17m 37.3s) |   C |    60 | 17.6 |        
    3052 | 2021-10-31 05:02:01 |          MASTER-IAC | (04h 50m 44.33s , -44d 25m 41.8s) |   C |    60 | 17.8 |        
    3052 | 2021-10-31 05:02:01 |          MASTER-IAC | (05h 01m 58.55s , -44d 31m 02.5s) |   C |    60 | 17.9 |        
    3132 | 2021-10-31 05:03:21 |          MASTER-IAC | (05h 34m 38.98s , -48d 11m 05.7s) |   C |    60 | 17.6 |        
    3132 | 2021-10-31 05:03:21 |          MASTER-IAC | (05h 46m 41.06s , -48d 16m 27.9s) |   C |    60 | 17.5 |        
    3212 | 2021-10-31 05:04:41 |          MASTER-IAC | (05h 22m 52.50s , -46d 18m 32.3s) |   C |    60 | 17.8 |        
    3212 | 2021-10-31 05:04:41 |          MASTER-IAC | (05h 34m 29.68s , -46d 23m 54.8s) |   C |    60 | 17.6 |        
    3292 | 2021-10-31 05:06:01 |          MASTER-IAC | (05h 12m 02.25s , -44d 25m 57.9s) |   C |    60 | 18.0 |        
    3292 | 2021-10-31 05:06:01 |          MASTER-IAC | (05h 23m 16.78s , -44d 31m 20.4s) |   C |    60 | 17.8 |        
    3372 | 2021-10-31 05:07:21 |          MASTER-IAC | (05h 47m 55.85s , -50d 06m 12.2s) |   C |    60 | 17.4 |        
    3372 | 2021-10-31 05:07:21 |          MASTER-IAC | (06h 00m 26.46s , -50d 11m 35.1s) |   C |    60 | 17.4 |        
Filter C is a clear (unfiltred) band. 


The observation and reduction will continue. 
The message may be cited.


