# GCN_circulars

GRB_name: GRB201209A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29094
SUBJECT: GRB 201209A: Mondy optical observations, afterglow confirmation
DATE:    20/12/20 10:46:03 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We observed the field of  GRB 201209A (Gropp et al., GCN 29005) with 
AZT-33IK telescope of Sayan observatory (Mondy) starting on Dec. 09 (UT) 
  11:41:13 (i.e. 0.28 days) and next epochs later. We detected a weak 
source within enhanced XRT position (Goad et al., GCN 29005) at ~1.4 
days after GRB 201209A trigger and not detected in other epochs.  Thus 
we confirm the optical afterglow detection on 0.321 days at R = 22.05 
+/- 0.16 (Zhu et al. GCN 29013).

Preliminary photometry of the field and afterglow is following

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

2020-12-09  11:41:13  42*120  R        0.27873   n/d    n/d  21.7
2020-12-10  14:26:13  45*120  R        1.39332   23.4   0.3  23.5
2020-12-12  11:14:21  39*120  R        3.25868   n/d    n/d  22.2
2020-12-13  12:03:41  38*120  R        4.26307   n/d    n/d  22.9

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


GRB_name: GRB201218A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29095
SUBJECT: Konus-Wind observation of GRB 201218A
DATE:    20/12/20 14:24:35 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks,
M. Ulanov, A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline
on behalf of the Konus-Wind team, report:

The long-duration, very bright GRB 201218A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 29081;
BALROG localization: Biltzinger et al., GCN Circ. 29083;
IPN triangulation: Hurley et al., GCN Circ. 29090)
triggered Konus-Wind at T0=15253.184 s UT (04:14:13.184).

The burst light curve shows a multipeaked structure
which starts at ~T0-17 s and has a total duration of ~55 s,
followed by a weak tail seen up to ~T0+120 s.
The emission is seen up to ~5 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB201218_T15255

As observed by Konus-Wind, the burst
had a fluence of 1.35(-0.07,+0.07)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+8.544 s,
of 2.23(-0.28,+0.29)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+20.736 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.82(-0.03,+0.03),
the high energy photon index beta = -3.00(-0.50,+0.27),
the peak energy Ep = 472(-24,+23) keV
(chi2 = 139/97 dof).

The spectrum near the maximum count rate
(measured from T0+8.192 to T0+8.704 s)
is best fit in the 20 keV - 10 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.72(-0.09,+0.09)
and Ep = 605(-68,+80) keV (chi2 = 51/63 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.5
(chi2 = 50/62 dof).

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB201221A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29096
SUBJECT: GRB 201221A: Swift detection of a burst
DATE:    20/12/21 07:20:48 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

K. L. Page (U Leicester), D. M. Palmer (LANL) and M. H. Siegel (PSU)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 07:09:01 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 201221A (trigger=1013852).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 214.477, -45.411 which is 
   RA(J2000) = 14h 17m 55s
   Dec(J2000) = -45d 24' 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 50 sec.  The peak count rate
was ~800 counts/sec (15-350 keV), at ~10 sec after the trigger. 

The XRT began observing the field at 07:11:17.8 UT, 136.5 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source located at RA, Dec 214.47885, -45.41606 which
is equivalent to:
   RA(J2000)  = 14h 17m 54.92s
   Dec(J2000) = -45d 24' 57.8"
with an uncertainty of 3.8 arcseconds (radius, 90% containment). This
location is 18 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 (9.32 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 5.3
(+4.59/-3.72) x 10^21 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 141 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
0.11. 

Burst Advocate for this burst is K. L. Page (klp5 AT leicester.ac.uk). 
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: GRB201221A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29097
SUBJECT: GRB 201221A: Prompt enhanced Swift-XRT position
DATE:    20/12/21 07:36:31 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

Using  promptly downlinked XRT event data for GRB 201221A, we find an
enhanced XRT position of the afterglow: RA, Dec: 214.4805, -45.4166
which is equivalent to:
   RA (J2000)  = 14 17 55.31
   Dec (J2000) = -45 24 59.9
with an uncertainty of 2.3 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/1013852.

Position enhancement is is described by Goad et al. (2007, A&A, 476,
1401) and Evans et al. (2009, MNRAS, 397, 1177).

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


GRB_name: GRB201221A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29098
SUBJECT: Swift GRB 201221A: Global MASTER-Net observations report 
DATE:    20/12/21 07:56:21 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) was pointed to the Swift GRB 201221A ( K. L. Page et al., GCN 29096) errorbox 76 sec after trigger time at 2020-12-21 07:10:17 UT, with upper limit up to  17.6 mag. The observations began at zenith distance = 65 deg. The sun  altitude  is -23.8 deg. 

The galactic latitude b = 14 deg., longitude l = 319 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1507781

We obtain a following upper limits.  

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

      86 |         MASTER-OAFA |   C |    20 | 17.3 |        
     126 |         MASTER-OAFA |   C |    20 | 17.2 |        
     170 |         MASTER-OAFA |   C |    30 | 17.5 |        
     225 |         MASTER-OAFA |   C |    40 | 17.6 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB201221A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29099
SUBJECT: GRB 201221A: FRAM-Auger optical limit
DATE:    20/12/21 08:29:10 GMT
FROM:    Martin Jelinek at Astro.Inst-AVCR,Ondrejov  <martin.jelinek@asu.cas.cz>

Martin Jelinek, Jan Strobl (ASU CAS Ondrejov, CZ),
Martin Masek, Petr Janecek, Sergey Karpov, Jakub
Jurysek, Jan Ebr, Ronan Cunniffe, Petr Travnicek and
Michael Prouza (Institute of Physics, Prague, CZ)

report:

The 30cm robotic telescope FRAM-Auger in Malargue (Argentina) reacted
robotically to the Swift/BAT alert of GRB201221A (Page et al., GCNC 29096,
Evans et al., GCNC 29097), starting with a series of 20 s R-band images at
07:10:13 UT, i.e. 72 s post trigger.

We do not detect any new or strongly variable source at or around the
reported gamma-ray errorbox in single frames nor in a combined 20 x 20 s
image spanning the period from 1.2 min to 12.1 min after the initial
trigger. The combined exposure has a 3-sigma limiting magnitude R(Vega) ~
17.5.


GRB_name: GRB201221A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29100
SUBJECT: GRB 201221A: VLT/X-shooter afterglow discovery and spectroscopic redshift z = 5.7
DATE:    20/12/21 13:16:00 GMT
FROM:    Daniele B Malesani at DTU Space  <malesani@space.dtu.dk>

D. B. Malesani (DTU Space), J.-B. Vielfaure (APC, Paris University), L. 
Izzo (DARK/NBI), S. D. Vergani (GEPI, Observatoire de Paris), D. 
Burgarella (AMU, CNRS, CNES, LAM), V. D'Elia (ASI/SSDC), A. de Ugarte 
Postigo (HETH/IAA-CSIC, DARK/NBI), J. P. U. Fynbo (DAWN/NBI), A. J. 
Levan (Radboud Univ.), B. Milvang-Jensen (DAWN/NBI), D. A. Kann 
(HETH/IAA-CSIC), E. Palazzi (INAF/OAS), G. Pugliese (API, Univ. 
Amsterdam), N. R. Tanvir (Univ. Leicester), K. Wiersema (Univ. Warwick), 
report on behalf of the Stargate consortium:

We observed the field of GRB 201221A (Page et al., GCN 29096) using the 
ESO VLT UT3 (Melipal) equipped with the X-shooter spectrograph.

Using the acquisition camera, multi-band imaging was secured. Within the 
XRT error circle (Evans, GCN 29097), no source is detected in an r-band 
image (taken at mean epoch of 42 min after the GRB) down to limiting 
magnitude r > 23.5 (AB). However, a source is clearly visible in the 
z-band image with z = 19.76 +- 0.04 AB (mean time 35 min after the GRB). 
The corresponding color r-z > 3.7 is exceptionally red. The coordinates 
of the object are (J2000, 0.3" error):

RA = 14:17:55.26
Dec = -45:24:58.0

Spectroscopy of the z-band source was executed covering the wavelength 
range 3000-25000 AA. Unfortunately due to visibility constraints, only 
two spectra by 600 s each were secured, plus two extra exposures during 
twilight which have lower quality. We report on the analysis of the 
first set only, which has a mean time of 1.65 hr after the GRB.

Continuum is well detected in the infrared arm, as well as in the red 
part of the visible arm. A clear break is detected around 8150 AA, 
which, if interpreted as the Lyman break, corresponds to z = 5.70. Weak 
continuum is detected blueward of the break, until it vanishes 
completely at the corresponding location of the Lyman limit. We thus 
conclude that z = 5.70 is the redshift of GRB 201221A.

Further analysis is undergoing.

We acknowledge support from the ESO observing staff at Paranal, in 
particular Zahed Wahhaj.


GRB_name: GRB201221B
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29101
SUBJECT: GRB 201221B: Fermi GBM Final Real-time Localization
DATE:    20/12/21 14:23:08 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 14:11:43 UT on 21 Dec 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 201221B (trigger 630252708.014426 / 201221591).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 110.6, Dec = 32.0 (J2000 degrees, equivalent to J2000 07h 22m, 32d 00'), with a statistical uncertainty of 4.1 degrees.

The angle from the Fermi LAT boresight is 14.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201221591/quicklook/glg_skymap_all_bn201221591.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201221591/quicklook/glg_healpix_all_bn201221591.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201221591/quicklook/glg_lc_medres34_bn201221591.gif


GRB_name: GRB201221A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29105
SUBJECT: GRB 201221A: Enhanced Swift-XRT position
DATE:    20/12/21 18:56:51 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 2103 s of XRT Photon Counting mode data and 5 UVOT
images for GRB 201221A, 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 = 214.48016, -45.41620 which is equivalent
to:

RA (J2000): 14h 17m 55.24s
Dec (J2000): -45d 24' 58.3"

with an uncertainty of 1.5 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: GRB201221C
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29106
SUBJECT: Swift Trigger 1014012: possible GRB 201221C
DATE:    20/12/21 19:07:16 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

K. L. Page (U Leicester), J.D. Gropp (PSU), J. A. Kennea (PSU),
N. J. Klingler (PSU), F. E. Marshall (NASA/GSFC), M. J. Moss (GWU) and
A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 18:41:33 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 201221C (trigger=1014012).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 278.205, +34.411 which is 
   RA(J2000) = 18h 32m 49s
   Dec(J2000) = +34d 24' 39"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty). As is typical for image triggers, there is 
nothing significant in the real-time light curves. 

The XRT began observing the field at 18:43:46.4 UT, 132.7 seconds after
the BAT trigger. No source was detected in 215 s of promptly downlinked
data. We are waiting for the full dataset to detect and localise the
XRT counterpart. 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 136 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 25% of
the BAT 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
BAT 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
0.07. 

Burst Advocate for this burst is K. L. Page (klp5 AT leicester.ac.uk). 
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: GRB201221C
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29107
SUBJECT: GRB 201221C: MASTER optical observtion
DATE:    20/12/21 19:41:01 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E.Gorbovskoy, N.Tiurina, P.Balanutsa,A.Kuznetsov,K.Zhirkov, F.Balakin,
V.Vladimirov, D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik, A.Chasovnikov,A.Pozdnyakov,
V.Topolev, 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, 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) was pointed to 
the  GRB201221.78 133 sec after notice time and 208 sec after trigger time 
at 2020-12-21 18:45:02 UT. On our 11-th (180s exposure)  set , obtained 
1451 sec after tigger time at 2020-12-21 19:05:45 UT, we haven't found 
optical transient  within Swift error-box (ra=278.204 dec=34.4108 r=0.05).
The 5-sigma upper limit has been about  13.6mag
The message may be cited.

The galactic latitude b = 18 deg., longitude l = 63 deg.
The observations made on zenith distance = 69 deg.The moon (48 % bright 
part) is 56 deg. above the horizon. The distance between  moon and  object 
is 87
  Observations started at twilight.
The sun  altitude  is -11.4 deg.
The object can be observed till sunrise at 2020-12-22 07:52:15 
The 5-sigma upper limit has been about  14.9mag The message may be cited.


GRB_name: GRB201221A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29108
SUBJECT: GRB 201221A: Swift-XRT refined Analysis
DATE:    20/12/21 21:57:31 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 6.2 ks of XRT data for GRB 201221A (Page et al. GCN
Circ. 29096), from 143 s to 23.8 ks after the  BAT trigger. The data
comprise 320 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Beardmore et al. (GCN Circ. 29097).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.71 (+/-0.04).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.39 (+0.16, -0.15). The
best-fitting absorption column is  6.3 (+8.3, -6.3) x 10^22 cm^-2, at a
redshift of 5.7, in addition to the Galactic value of 9.3 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 5.0 x 10^-11
(4.7 x 10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Galactic foreground: 9.3 x 10^20 cm^-2
Intrinsic column:    6.3 (+8.3, -6.3) x 10^22 cm^-2 at z=5.7
Photon index:      1.39 (+0.16, -0.15)

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 0.016 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.0 x
10^-13 (7.4 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/01013852.

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


GRB_name: GRB201221A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29109
SUBJECT: GRB 201221A: Swift/UVOT Upper Limits
DATE:    20/12/21 22:06:23 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and K. L. Page (U. Leicester) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 201221A 141 s after the BAT trigger 
(Page et al., GCN Circ. 29096). No optical afterglow consistent with the optical position (Malesani 
et al. GCN Circ. 29100) 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           141          291          147         >20.0
u_FC               300          549          246         >19.1
white              141          951          257         >20.2
v                  629         4762          236         >18.8
b                  555          748           39         >18.3
u                  300         5271          357         >19.5
w1                 679         5172          236         >19.4
m2                 654         4967          236         >19.2
w2                 605         4557          235         >19.4

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of 
E(B-V) = 0.11 in the direction of the burst (Schlegel et al. 1998).


GRB_name: GRB201221A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29110
SUBJECT: Fermi GBM Sub-Threshold Detection of GRB 201221A    
DATE:    20/12/21 22:28:27 GMT
FROM:    Peter Veres at UAH  <veresp@gmail.com>

P. Veres (UAH) reports on behalf of the Fermi-GBM Team:

"At 07:09:01 UT on 21 December, 2020 Swift detected GRB 201221A  (Page
et al. GCN 29096). There was no Fermi-GBM onboard trigger around the
event.

An automated, blind search for short gamma-ray bursts below the
onboard triggering threshold in Fermi-GBM identified a long
counterpart with high significance.  This was not included in the
public list (https://gcn.gsfc.nasa.gov/gcn/fermi_gbm_subthresh_archive.html),
because the search reports only short candidates.

The GBM targeted search [1], the most sensitive, coherent search for
GRB-like signals identified a transient most significantly on the
8.192 s timescale, with a log likelihood ratio of 52 and a location
consistent with the event.

The GBM light curve consists of a single peak. The time-averaged
spectrum from T0-10 s to T0+47 s is best fit by a power law function
with an exponential high-energy cutoff (T0 is the Swift trigger time).
The power law index is -1.17 +/- 0.21 and the cutoff energy,
parameterized as Epeak, is 129 +/- 28 keV.

The event fluence (10-1000 keV) in this time interval is (3.30 +/-
0.27)E-04 erg/cm^2. Using the redshift z=5.7 reported by Malesani et
al (GCN 29100),  we derive an isotropic equivalent energy in the
1-10,000 keV range of (2.02 +/- 0.16)E+55 erg.

This analysis is preliminary.

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

[GCN OPS NOTE(22Dec2020): The 5th paragraph contains some errors
in the number results.  Please see Circ 29111 for the correct values.]


GRB_name: GRB201221A
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29111
SUBJECT: correction to GCN 29110 - Fermi GBM Sub-Threshold Detection of GRB 201221A
DATE:    20/12/21 23:14:59 GMT
FROM:    Peter Veres at UAH  <veresp@gmail.com>

P. Veres (UAH) reports:

In GCN 29110 we reported the sub-threshold detection of GRB 201221A. The
reported fluence  value contained an error. The corrected paragraph reads:

"
The event fluence (10-1000 keV) in the T0-10 s to T0+47 s time interval (T0
is the Swift trigger time) is (3.6 +/- 0.4)E-06 erg/cm^2. Using the
redshift z=5.7 reported by Malesani et al (GCN 29100),  we derive an
isotropic equivalent energy in the 1-10,000 keV range of (2.2 +/- 0.2)E+53
erg.
"

We apologize for the confusion this may have caused.


GRB_name: GRB201221D
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29112
SUBJECT: GRB 201221D: Swift detection of a bright short burst
DATE:    20/12/21 23:16:01 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

K. L. Page (U Leicester), S. D. Barthelmy (GSFC), J.D. Gropp (PSU),
J. A. Kennea (PSU), N. J. Klingler (PSU), S. Laha (GSFC/UMBC/CRESST),
A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC),
B. Sbarufatti (PSU), M. H. Siegel (PSU) and A. Tohuvavohu (U Toronto)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 23:06:34 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 201221D (trigger=1014037).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 171.049, +42.144 which is 
   RA(J2000) = 11h 24m 12s
   Dec(J2000) = +42d 08' 39"
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 ~9000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 23:08:01.7 UT, 87.4 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 171.05873, 42.14332 which is equivalent
to:
   RA(J2000)  = 11h 24m 14.10s
   Dec(J2000) = +42d 08' 36.0"
with an uncertainty of 5.7 arcseconds (radius, 90% containment). This
location is 26 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. 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 92 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
0.02. 

Burst Advocate for this burst is K. L. Page (klp5 AT leicester.ac.uk). 
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: GRB201221D
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29113
SUBJECT: GRB 201221D: Prompt enhanced Swift-XRT position
DATE:    20/12/21 23:32:42 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

Using  promptly downlinked XRT event data for GRB 201221D, we find an
enhanced XRT position of the afterglow: RA, Dec: 171.0587, 42.1438
which is equivalent to:
   RA (J2000)  = 11 24 14.09
   Dec (J2000) = +42 08 37.5
with an uncertainty of 4.2 arcseconds (radius, 90% confidence).
Analysis of the promptly available data is online at
http://www.swift.ac.uk/sper/1014037.

Position enhancement is is described by Goad et al. (2007, A&A, 476,
1401) and Evans et al. (2009, MNRAS, 397, 1177).

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


GRB_name: GRB201221E
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29114
SUBJECT: GRB 201221E: Fermi GBM Final Real-time Localization
DATE:    20/12/21 23:50:46 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 23:28:47 UT on 21 Dec 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 201221E (trigger 630286132.63327 / 201221978).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 158.1, Dec = -39.9 (J2000 degrees, equivalent to J2000 10h 32m, -39d 53'), with a statistical uncertainty of 5.2 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/2020/bn201221978/quicklook/glg_skymap_all_bn201221978.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201221978/quicklook/glg_healpix_all_bn201221978.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201221978/quicklook/glg_lc_medres34_bn201221978.gif


GRB_name: GRB201222A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29115
SUBJECT: GRB 201222A: Fermi GBM Final Real-time Localization
DATE:    20/12/22 00:22:39 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 00:12:18 UT on 22 Dec 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 201222A (trigger 630288743.68768 / 201222009).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 215.7, Dec = 13.5 (J2000 degrees, equivalent to J2000 14h 22m, 13d 30'), with a statistical uncertainty of 8.1 degrees.

The angle from the Fermi LAT boresight is 6.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201222009/quicklook/glg_skymap_all_bn201222009.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201222009/quicklook/glg_healpix_all_bn201222009.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201222009/quicklook/glg_lc_medres34_bn201222009.gif


GRB_name: GRB201221A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29116
SUBJECT: GRB 201221A: Swift-BAT refined analysis
DATE:    20/12/22 01:05:18 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

S. D. Barthelmy (GSFC), J. R. Cummings (CPI),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL),
T. Sakamoto (AGU), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (i.e. the Swift-BAT team):

Using the data set from T-240 to T+963 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 201221A (trigger #1013852)
(Page et al., GCN Circ. 29096).  The BAT ground-calculated position is
RA, Dec = 214.488, -45.406 deg which is
   RA(J2000)  =  14h 17m 57.1s
   Dec(J2000) = -45d 24' 20.8"
with an uncertainty of 1.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 42%.

The mask-weighted light curve shows a weak pulse that starts at ~T-7 s
and ends at ~T+40 s. T90 (15-350 keV) is 44.5 +- 6.2 sec (estimated error
including systematics).

The time-averaged spectrum from T-7.63 to T+41.72 sec is best fit by
a simple power-law model.  The power law index of the time-averaged
spectrum is 1.40 +- 0.15.  The fluence in the 15-150 keV band
is 1.9 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured
from T+4.16 sec in the 15-150 keV band is 1.0 +- 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/1013852/BA/


GRB_name: GRB201221D
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29117
SUBJECT: GRB 201221D: candidate optical counterpart from the NOT
DATE:    20/12/22 01:34:37 GMT
FROM:    Daniele B Malesani at DTU Space  <malesani@space.dtu.dk>

D. B. Malesani (DTU Space) and E. Knudstrup (NOT and Aarhus Univ.) 
report on behalf of a larger collaboration:

We observed the field of GRB 201221D (Page et al., GCN 29112) using the 
Nordic Optical Telescope (NOT) equipped with the ALFOSC imaging camera. 
Observations were carried out using the SDSS r (3x300 s) and z (5x200 s) 
filters. The data were taken as soon as the target rised, so at quite 
high airmass (2.9 to 2.3), yielding a seeing of ~1.5".

Inside or close to the XRT werror circle (current uncertainty 4.2": 
https://www.swift.ac.uk/xrt_positions/), a very faint object is detected 
in the stack of the r-band images. Calibrating against nearby stars from 
the Pan-STARRS catalog, we measure r = 23.1 +- 0.3 (AB), at a mean epoch 
2020 Dec 22.032 UT (1.67 hr after the GRB). Its coordinates are:

RA = 11:24:14.02
Dec = +42:08:39.97

No object is visible at this location in the Pan-STARRS r-band image, 
which has however a limiting magnitude (r ~ 23.3 AB) comparable to our 
measurement. Given the lack of variability and the still relatively 
large XRT error circle size, we cannot confirm at the present time 
whether this object is associated with GRB 201221D. Further observations 
are planned.


GRB_name: GRB201221D
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29118
SUBJECT: GRB 201221D: Nanshan/NEXT early optical upper limit
DATE:    20/12/22 01:38:32 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

D. Xu (NAOC), Z.P. Zhu (NAOC, HUST), S.Y. Fu, X. Liu (NAOC), X. Gao 
(Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:

We observed the field of GRB 201221D (Page et al., GCN 29112) using the 
NEXT-0.6m optical telescope located at Nanshan, Xinjiang, China. 
Observations automatically started at 23:07:39 UT on 2020-12-21, i.e., 
65 s after the BAT trigger. We obtained 3x40s, 4x60s and 12x90s frames 
in the Sloan r-filter.

No optical source is detected in our stacked image at the XRT enhanced 
position (Evans et al., GCN 29113), down to a upper limit of r~21.3, 
calibrated with the nearby PanSTARRS field.


GRB_name: GRB201221D
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29119
SUBJECT: GRB 201221D: Enhanced Swift-XRT position
DATE:    20/12/22 01:46:49 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 651 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 201221D, 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 = 171.05914, +42.14319 which is equivalent
to:

RA (J2000): 11h 24m 14.19s
Dec (J2000): +42d 08' 35.5"

with an uncertainty of 3.9 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: GRB201221E
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29121
SUBJECT: Fermi GRB 201221E: Global MASTER-Net observations report 
DATE:    20/12/22 05:30:33 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 201221E ( Fermi GBM team, GCN 29114) errorbox  19065 sec after notice time and 20298 sec after trigger time at 2020-12-22 05:07:05 UT, with upper limit up to  18.7 mag. The observations began at zenith distance = 49 deg. The sun  altitude  is -35.0 deg. 

The galactic latitude b = 16 deg., longitude l = 276 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1508233

We obtain a following upper limits.  

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

   20328 | 2020-12-22 05:07:05 |         MASTER-OAFA | (10h 39m 23.18s , -41d 10m 51.0s) |   C |    60 | 18.6 |        
   20407 | 2020-12-22 05:08:25 |         MASTER-OAFA | (10h 50m 13.21s , -41d 11m 40.1s) |   C |    60 | 18.5 |        
   20487 | 2020-12-22 05:09:44 |         MASTER-OAFA | (10h 26m 46.41s , -35d 13m 03.7s) |   C |    60 | 18.6 |        
   20566 | 2020-12-22 05:11:04 |         MASTER-OAFA | (10h 36m 45.15s , -35d 12m 44.4s) |   C |    60 | 18.7 |        
   20646 | 2020-12-22 05:12:23 |         MASTER-OAFA | (10h 28m 41.13s , -41d 11m 05.1s) |   C |    60 | 18.5 |        
   20934 | 2020-12-22 05:17:11 |         MASTER-OAFA | (10h 51m 32.55s , -39d 10m 36.3s) |   C |    60 | 18.7 |        
   21013 | 2020-12-22 05:18:30 |         MASTER-OAFA | (10h 16m 14.44s , -43d 12m 07.6s) |   C |    60 | 18.5 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB201221D
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29122
SUBJECT: Swift GRB 201221D: Global MASTER-Net observations report 
DATE:    20/12/22 08:54:08 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) was pointed to the Swift GRB 201221D ( K. L. Page et al., GCN 29112) errorbox  33444 sec after notice time and 33517 sec after trigger time at 2020-12-22 08:25:12 UT, with upper limit up to  17.5 mag. Observations started at twilight.  The observations began at zenith distance = 75 deg. The sun  altitude  is -12.3 deg. 

The galactic latitude b = 67 deg., longitude l = 167 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1508187

We obtain a following upper limits.  

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

   33608 |         MASTER-OAFA |   C |   180 | 17.5 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB201221D
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29124
SUBJECT: GRB 201221D: Swift-XRT refined Analysis
DATE:    20/12/22 09:36:27 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 6.7 ks of XRT data for GRB 201221D (Page et al. GCN
Circ. 29112), from 96 s to 23.5 ks after the  BAT trigger. The data are
entirely in Photon Counting (PC) mode. The enhanced XRT position for
this burst was given by Evans et al. (GCN Circ. 29113). The source is
fading with alpha >0.4.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01014037.

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


GRB_name: GRB201221D
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29125
SUBJECT: GRB 201221D: FRAM-ORM optical limit
DATE:    20/12/22 10:25:06 GMT
FROM:    Martin Jelinek at Astro.Inst-AVCR,Ondrejov  <martin.jelinek@asu.cas.cz>

Martin Jelinek and Jan Strobl (ASU CAS Ondrejov, CZ),
Sergey Karpov, Martin Masek, Petr Janecek, Jakub Jurysek,
Jan Ebr, Ronan Cunniffe, Petr Travnicek and Michael Prouza
(Institute of Physics, Prague, CZ)

report:

The 25cm robotic telescope FRAM-ORM at La Palma (Spain) reacted robotically
to the Swift alert of GRB201221D (Page et al., GCNC 29112 and Evans et al.
GCNC 29113, GCNC 29119 and 29124), obtaining a series of 20s unfiltered
images starting at 23:07:11.9 UT, i.e. 37.6s post trigger.

We do not detect any new or strongly variable source neither in single
images (detection limit R>~16.9) nor in a combined 40x20s frame (mean exp
time 560s post trigger, with a limit R>~18.5). While we analysed the entire
25'x25' field of view centred at the XRT localization, we did pay a special
attention to the location of the candidate afterglow mentioned by Malesani
& Knudstrup (GCNC 29117) with a negative outcome.


GRB_name: GRB201222B
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29126
SUBJECT: GRB 201222B: Fermi GBM Final Real-time Localization
DATE:    20/12/22 11:10:57 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 11:03:25 UT on 22 Dec 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 201222B (trigger 630327810.6864 / 201222461).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 95.7, Dec = 27.9 (J2000 degrees, equivalent to J2000 06h 22m, 27d 53'), with a statistical uncertainty of 5.0 degrees.

The angle from the Fermi LAT boresight is 107.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201222461/quicklook/glg_skymap_all_bn201222461.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201222461/quicklook/glg_healpix_all_bn201222461.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201222461/quicklook/glg_lc_medres34_bn201222461.gif


GRB_name: GRB201222B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29127
SUBJECT: GRB 201222B: BALROG localization (Fermi Trigger  / GRB 201222461)
DATE:    20/12/22 11:45:58 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
 at 11:03:25 on 22 Dec. 2020 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) = 99.7+/-3.0 deg
Decl.(2000.0) = 27.7+/-4.7 deg
We estimate an additional systematic error of 1 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB201222461/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB201222461/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB201222461/json

                        


GRB_name: GRB201221D
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29128
SUBJECT: GRB 201221D: Lowell Discovery Telescope afterglow observations
DATE:    20/12/22 12:59:55 GMT
FROM:    Simone Dichiara at UMCP/NASA/GSFC  <dichiara@umd.edu>

S.Dichiara (UMD, NASA-GSFC), E. Troja (UMD, NASA-GSFC), S.B. Cenko
(NASA-GSFC),  B. O'Connor (GWU, UMD), P. Gatkine (Caltech), J.M. Durbak
(UMD), A. Kutyrev (UMD, NASA-GSFC), S. Veilleux (UMD), report on behalf
of a larger
collaboration:

We observed the short GRB 201221D (Page et al., GCN 29112) using the
Large Monolithic Imager (LMI) on the 4.3m Lowell Discovery Telescope
(LDT) at Happy Jack, AZ. Observations started on December 22, at 09:13:28
UT (about 10.11 hours after the Swift trigger)
with SDSS r, i and z filters. Observations were taken at an airmass of
about 1.3 and seeing of about 0.8".

At the position of the optical candidate counterpart (Malesani et al.,
GCN 29117) we detect a source in all bands with r~23.9 AB mag and i~23.7
AB mag. This is fainter than the value reported by Malesani et al.
(r~23.1 at 1 hr) and may suggest that the source faded between the two
epochs. However, we note that at the same position a weak source is
visible in archival Pan-STARRS images, which we suggest as the putative
GRB host galaxy.
Our observations could be dominated by the galaxy's contribution, and
further observations to determine variability are planned.

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


GRB_name: GRB201221D
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29129
SUBJECT: GRB 201221D: Swift/UVOT Upper Limits
DATE:    20/12/22 13:27:07 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and K. L. Page (U. Leicester) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 201221D 92 s after the BAT trigger 
(Page et al., GCN Circ. 29112). No optical afterglow consistent with the NOT or XRT position 
(Malesani et al. GCN Circ. 29117; Evans et al. GCN Circ. 29119) 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            92          242          147         >20.3
u_FC               305          554          246         >19.3
white             4047         4247          197         >21.0
v                  634         4657          216         >19.2
u                  305         5110          282         >19.4
w1                 684         5068          216         >19.7
m2                4663         4863          197         >19.5
w2                4253         4453          197         >19.9

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of 
E(B-V) = 0.02 in the direction of the burst (Schlegel et al. 1998).


GRB_name: GRB201221D
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29130
SUBJECT: Konus-Wind detection of GRB 201221D (short)
DATE:    20/12/22 13:33:30 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

D. Frederiks, S. Golenetskii, R.Aptekar, A.Lysenko,
A. Ridnaia, D. Svinkin, A. Tsvetkova,  M. Ulanov, and T. Cline,
on behalf of the Konus-Wind team, report:

The short GRB 201221D (Swift detection:  Page et al., GCN 29112)
triggered Konus-Wind (KW) at T0=83197.636 s UT (23:06:37.636).

The burst light curve shows a single pulse with the total duration of ~1.9 s (20-1500 keV).
The emission is seen up to ~1 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB201221_T83197/

As observed by Konus-Wind, the burst had
a fluence of (5.3 Â± 1.1)x10^-7 erg/cm^2 and
a 16-ms peak energy flux, measured from T0-0.016 s,
of (6.6 Â± 1.3)x10^-6 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).

The spectrum of the burst (measured from T0 to T0+0.128 s)
is best fit in the 20 keV - 1.5 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.95(-0.52,+0.64)
and Ep = 148(-37,+86) keV (chi2 = 19/20 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.1
(chi2 =19/19 dof).

All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.


GRB_name: GRB201221D
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29132
SUBJECT: Short GRB201221D: High Redshift from OSIRIS/GTC
DATE:    20/12/22 14:49:53 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

A. de Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), D. A. Kann 
(HETH/IAA-CSIC), L. Izzo (DARK/NBI), C.C. Thoene, M. Blazek, J. F. Agui 
Fernandez (all HETH/IAA-CSIC) and G. Lombardi (GRANTECAN, IAC) report:

We obtained spectroscopy of the optical counterpart (Malesani et al., 
GCN #29117) of the short GRB 201221D (Page et al., GCN #29112) with 
OSIRIS at the 10.4m Gran Telescopio Canarias (Roque de los Muchachos 
Observatory, La Palma, Spain), starting at 1:52 UT (2.757 hr after the 
burst). The observation consisted of 4 x 1200 s exposures with the 
R1000B grism, covering the range between 3700 and 7800 Angstrom.

The spectrum shows a weak continuum over the full spectral range. There 
is a prominent emission feature that we identify as the [OII] 3727/3729 
doublet at a redshift of 1.046. This line happens to lie in the 
atmospheric A band, and therefore must be quite strong to be detectable. 
There are also low significance absorption featuress coincident with 
FeII and MgII at a similar redshift (z = 1.045). We identify this as the 
redshift of GRB 201221D. We note this is a high redshift for a short 
GRB, and it represents one of the few short GRB spectra to show 
afterglow absorption features.


GRB_name: GRB201221D
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29133
SUBJECT: GRB 201221D: Archival PS1 Imaging of the Putative Host Galaxy
DATE:    20/12/22 15:34:10 GMT
FROM:    Charles Kilpatrick at UC Santa Cruz  <cdkilpat@ucsc.edu>

C. D. Kilpatrick (Northwestern), D. B. Malesani (DTU Space), and W. Fong (Northwestern), report:

â€œWe analyzed stacked images from the PS1 Data Release 1 image archive (Flewelling et al., 2016, arXiv:1612.05243) of the location of the short-duration GRB 201221D (Page et al., GCN 29112).  We detected a single source centered at:

RA (J2000): 11:24:14.01
Dec (J2000): +42:08:39.69

in PS1 g-band, 4.6 arcseconds from the latest enhanced XRT position of GRB 201221D (Evans et al., GCN 29119).  We note that this places the centroid of the candidate host galaxy just outside the enhanced XRT error circle reported by GCN 29119, which has a radius of 3.9 arcsec (90% confidence), although consistent with the real-time XRT error circle at https://www.swift.ac.uk/xrt_positions/01014037/ <https://www.swift.ac.uk/xrt_positions/01014037/>. Performing forced aperture photometry on this position with an aperture fixed to the FWHM size in all PS1 bands (approximately 1.1 arcseconds), we found that this source has a brightness:

g = 23.2 +/- 0.2 mag
r > 23.2 mag
i > 23.3 mag
z > 22.2 mag
y = 22.6+/-0.2 mag

All magnitudes are given in AB.  We note that this source is coincident with emission identified in Malesani & Knudstrup (GCN 29117) who find a source with r = 23.1+/-0.3 mag (AB) in NOT follow up imaging.  Similarly, Dichiara et al. (GCN 29128) find r=23.9 mag and i=23.7 mag (AB), all of which are consistent with our limiting magnitudes.  Based on this photometry, it is fully plausible that the reported optical candidate (GCN 29117, GCN 29128) is dominated by the host galaxy.  However, the detection of absorption features in the spectrum (de Ugarte Postigo et al., GCN 29132), coupled with the possible r-band fading between NOT and DCT observations (reported in GCN 29128) may indicate the presence of an optical afterglow on top of the host emission. Image subtraction will be required to test for fading, and further, deep optical observations are encouraged.


GRB_name: GRB201216A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29137
SUBJECT: GRB 201216A - further Swift-XRT observations
DATE:    20/12/22 16:55:43 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans (U. Leicester), A. Tohuvavohu (U Toronto), J.A. Kennea (PSU) and T.
Sbarrato (INAF-OAB) report on behalf of the Swift-XRT team.

Swift has reobserved the field of GRB 201216A (GCN Circs. 29057, 29059) for a
further 4 ks, between 00:18 UT and 11:58 UT on 2020 December 22.

One of the sources in the XRT field of view appears to have faded (with 2.1
sigma significance). This source, â€œsource 5â€ in the automated analysis
(https://www.swift.ac.uk/ToO_GRBs/00021408/) is located at RA,Dec = 201.45786,
+36.3944, which is equivalent to:

RA(J2000):  13h 25m 49.89s
Dec (J2000): +36d 23â€™ 39.8â€

with an uncertainty of 3.0 arcsec (radius, 90% confidence). This position is 5.2
arcmin away from the BAT/GUANO position (Tohovavohu et al. GCN Circ. 29059),
well outside the 3 arcmin, 90% confidence BAT error region. It is also
coincident with a catalogued object in (among others) the USNO-B1, 2MASS, SDSS
and WISE catalogues, which NED classifies as a galaxy. 

We suggest therefore that this source is most likely simply a variable AGN near
(in projection) to GRB 201216A, but cannot rule out the possibility of it being
the GRB afterglow.

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


GRB_name: GRB201221C
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29138
SUBJECT: Swift Trigger 1014012 (possible GRB 201221C) is likely not an astrophysical event
DATE:    20/12/22 17:42:53 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

S. D. Barthelmy (GSFC), A. Y. Lien (GSFC/UMBC) and K. L. Page (U Leicester)
report on behalf of the Neil Gehrels Swift Observatory Team:

Using the full data set from recent downlinks, we report further ground
data analysis for Swift trigger 1014012 (Page et al. GCN Circ. 29106).

The BAT analysis uses data from T-239 to T+963 sec. The BAT image
significance has now decreased to 5.2 sigma (15-350 keV). Also, the
mask-weighted light curve does not show anything significant.

There is no good evidence for an X-ray source in 4.7 ks data, to a 3 sigma
upper limit of 2.3x10^-3 count s^-1 (corresponding to an observed flux of
1x10^-13 erg cm^-2 s^-1, assuming a typical power-law spectrum).

We therefore conclude that this event is likely due to noise,
and is not an astrophysical event.


GRB_name: GRB201221D
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29139
SUBJECT: GRB 201221D: Swift-BAT refined analysis
DATE:    20/12/22 17:44:15 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

H. A. Krimm (NSF), S. D. Barthelmy (GSFC),
S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), K. L. Page (U Leicester),
D. M. Palmer (LANL), T. Sakamoto (AGU),
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(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 201221D (trigger #1014037)
(Page et al., GCN Circ. 29112).  The BAT ground-calculated position is
RA, Dec = 171.055, 42.152 deg which is
   RA(J2000)  =  11h 24m 13.2s
   Dec(J2000) = +42d 09' 08.4"
with an uncertainty of 1.3 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 23%.

The mask-weighted light curve shows a single-peaked structure that
starts at ~T-0.06 s, peaks at ~T+0.02 s, and ends at ~T+0.2 s.
T90 (15-350 keV) is 0.16 +- 0.04 sec (estimated error including
systematics).

The time-averaged spectrum from T-0.06 to T+0.17 sec is best fit by
a simple power-law model.  The power law index of the time-averaged
spectrum is 1.56 +- 0.13.  The fluence in the 15-150 keV band is
3.9 +- 0.4 x 10^-7 erg/cm2. The 1-sec peak photon flux measured from
T-0.44 sec in the 15-150 keV band is 5.6 +- 0.5 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/1014037/BA/


GRB_name: GRB201221D
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29140
SUBJECT: GRB 201221D: Fermi GBM detection
DATE:    20/12/22 18:52:47 GMT
FROM:    Rachel Hamburg at UAH  <rkh0007@uah.edu>

R. Hamburg (UAH), C. Malacaria (NASA-MSFC/USRA), and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 23:06:34.33 UT on 21 December 2020, the Fermi Gamma-Ray Burst Monitor
(GBM)
triggered and located GRB 201221D (trigger 630284799 / 201221963)
which was also detected by the Swift/BAT and Swift/XRT
(Page et al. 2020, GCN 29112) and Konus-Wind (Frederiks et al. 2020,
GCN 29130). This trigger was initially classified as a  particle event by
the flight software, but is in fact a GRB. The GBM on-ground location is
consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 89
degrees.

The GBM light curve shows a single-peaked structure
with a duration (T90) of about 0.14 s (50-300 keV).
The time-averaged spectrum from T0-0.064 s to T0+0.192 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.20 +/- 0.16 and
the cutoff energy, parameterized as Epeak, is 108 +/- 5 keV.
A Band function fits the spectrum equally well with
Epeak = 98 +/- 8 keV, alpha = 0.01 +/- 0.24 and beta = -3.3 +/- 0.5.

The event fluence (10-1000 keV) in this time interval is
(1.076 +/- 0.046)E-06 erg/cm^2. The 64-ms peak photon flux measured
starting from T0+0.00 s in the 10-1000 keV band is 41 +/- 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: GRB201221D
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29141
SUBJECT: GRB 201221D: LCOGT upper limits
DATE:    20/12/22 19:18:16 GMT
FROM:    Igor Andreoni at Caltech  <igor.andreoni@gmail.com>

Igor Andreoni (Caltech), Michael M. Coughlin (UMN)
on behalf of the Global Relay of Observatories Watching Transients Happen
(GROWTH) collaboration


We used the Sinistro camera on the 1-m LCO Global Telescope Network (LCOGT,
Brown et al., 2013) to observe the afterglow of short-duration GRB 201221D
(Page et al., GCN #29112).

Two sets of 300s exposures were acquired in g-r-i bands between
2020-12-22T07:57 and 2020-12-22T08:47 UTC. The observations were performed
under proposal IDs TOM2020A-008 (PI Andreoni) and NOAO2020B-005 (PI
Coughlin).

We do not identify any source within 3.9 arcsec of the enhanced Swift-XRT
position (Evans et al., GCN #29119). Photometric upper limits, calibrated
against Pan-STARRS DR1 magnitudes (Chambers et al., 2016), were measured to
be g > 22.8, r > 22.2, and i > 21.5 mag (5-sigma) after image stacking.

The candidate optical counterpart (transient or host galaxy: Malesani et
al., GCN #29117; Dichiara et al., GCN #29128; de Ugarte Postigo et al., GCN
#29132; Kilpatrick et al., GCN #29133) is too faint to be detectable in our
observations, which did not show any significant brightening, as expected.



We thank the TOM Community Development Program and the TOM Toolkit Workshop
organizers for the generous LCOGT time allocation. GROWTH is a worldwide
collaboration 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; IIT-B, India; IIA, India; LJMU, TTU,
USyd, Australia, and SDSU, USA. GROWTH acknowledges generous support of the
NSF under PIRE Grant No 1545949.


GRB_name: GRB201221D
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29142
SUBJECT: GRB 201221D: MMT MMIRS detection of marginally extended source
DATE:    20/12/22 22:39:03 GMT
FROM:    Jillian Rastinejad at Northwestern Univ.  <jillianrastinejad2024@u.northwestern.edu>

J. Rastinejad, K. Paterson, C. D. Kilpatrick, W. Fong (Northwestern) report:

We observed the location of the Swift GRB 201221D (Page et al., GCN 29112) with the MMT and Magellan Infrared Spectrograph (MMIRS) mounted on the MMT 6.5-meter telescope on Mount Hopkins, Arizona. We obtained 25x60-sec imaging in J-band at a mid-time of 2020 December 22.36 UT (0.40 days post-burst). Within the vicinity of the XRT position (Evans et al., GCN 29113; Evans et al., GCN 29119), we detect a marginally extended source, consistent with the location of emission detected in previously reported optical follow up and archival imaging (Malesani et al., GCN 29117; Dichiara et al., GCN 29128; de Ugarte Postigo et al., GCN 29132; Kilpatrick et al., GCN 29133).

After calibrating our stacked image to isolated stars detected in the 2MASS photometric catalog (Cutri et al., 2003, NASA/IPAC), we applied a 3 arcsecond aperture and measure a magnitude of J = 21.8 +/- 0.2 mag (AB and not corrected for Milky Way extinction).

Further observations are planned to assess any variability of the source. We thank Ryan Howie and Joannah Hinz at the MMT for the rapid scheduling and execution of these observations.


GRB_name: GRB201222B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29143
SUBJECT: Fermi GRB 201222B: Global MASTER-Net observations report 
DATE:    20/12/23 01:15:28 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 201222B ( Fermi GBM team, GCN 29126) errorbox  49075 sec after notice time and 49125 sec after trigger time at 2020-12-23 00:42:11 UT, with upper limit up to  17.3 mag. Observations started at twilight.  The observations began at zenith distance = 77 deg. The sun  altitude  is -12.3 deg. 

The galactic latitude b =  7 deg., longitude l = 185 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1509240

We obtain a following upper limits.  

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

   49156 | 2020-12-23 00:42:11 |         MASTER-OAFA | (06h 02m 01.37s , +23d 18m 10.6s) |   C |    60 | 16.0 |        
   49315 | 2020-12-23 00:44:50 |         MASTER-OAFA | (06h 13m 54.23s , +21d 18m 00.8s) |   C |    60 | 16.4 |        
   49635 | 2020-12-23 00:50:11 |         MASTER-OAFA | (05h 56m 25.50s , +27d 17m 21.2s) |   C |    60 | 16.4 |        
   49874 | 2020-12-23 00:54:09 |         MASTER-OAFA | (06h 07m 58.78s , +25d 17m 26.6s) |   C |    60 | 16.5 |        
   50033 | 2020-12-23 00:56:48 |         MASTER-OAFA | (06h 19m 26.67s , +23d 18m 41.9s) |   C |    60 | 16.8 |        
   50113 | 2020-12-23 00:58:08 |         MASTER-OAFA | (06h 01m 56.11s , +23d 19m 19.9s) |   C |    60 | 17.1 |        
   50193 | 2020-12-23 00:59:28 |         MASTER-OAFA | (06h 10m 47.69s , +23d 18m 33.8s) |   C |    60 | 17.0 |        
   50356 | 2020-12-23 01:02:11 |         MASTER-OAFA | (05h 59m 04.32s , +25d 17m 30.8s) |   C |    60 | 17.2 |        
   50436 | 2020-12-23 01:03:31 |         MASTER-OAFA | (06h 13m 54.45s , +21d 19m 15.0s) |   C |    60 | 17.3 |        
   50516 | 2020-12-23 01:04:51 |         MASTER-OAFA | (06h 22m 32.36s , +21d 18m 24.3s) |   C |    60 | 17.2 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB201221D
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29144
SUBJECT: GRB 201221D: SMA submm observation 
DATE:    20/12/23 02:49:57 GMT
FROM:    Yuji Urata at Nat. Central U.  <urata@astro.ncu.edu.tw>

Huang, K. (CYCU), Urata, Y. (NCU) and Petitpas, G (SAO). report:

We observed the field of the GRB201221D (Page et al., GCN #29112) at
228 GHz using the Submillimeter Array (SMA).  The observation was
started at 2020 December 11:27 UT (12.3 h after the burst).  There was
no source at the candidate of optical afterglow (Malesani et al., GCN
#29117; Dichiara et al., GCN #29128; de Ugarte Postigo et al., GCN
#29132; Kilpatrick et al., GCN #29133; Rastinejad et al. GCN #29142).
The preliminary limit of the observation is ~0.2 mJy (rms).

We thank Ramprasad Rao, Mark Gurwell and staff of SMA for the
scheduling and execution of observations.


GRB_name: GRB201221B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29147
SUBJECT: GRB 201221B: Insight-HXMT/HE detection
DATE:    20/12/23 11:32:53 GMT
FROM:    Ce Cai at IHEP  <caice@ihep.ac.cn>

C. Cai, S. Xiao, Y. F. Du, Y. G. Zheng, Q. Luo, Q. B. Yi, 
Y. Huang, C. K. Li, G. Li, X. B. Li, J. Y. Liao, S. L. Xiong,
C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, A. M. Zhang, 
Y. F. Zhang, X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, 
Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, 
M. Wu, Y. P. Xu, S. N. Zhang (IHEP), 
report on behalf of the Insight-HXMT team:

At 2020-12-21T14:11:43.00 (T0), Insight-HXMT/HE detected 
GRB 201221B (trigger ID: HEB201221591) in a routine search of the data, 
which also triggered Fermi/GBM (GCN #29101).

The Insight-HXMT/HE light curve mainly consists of a single 
pulse with a duration (T90) of 0.03 s measured from T0-0.00 s. 
The 1-ms peak rate, measured from T0-0.005 s, is 9739 cnts/sec. 
The total counts from this burst is 193 counts. 
URL_LC: http://twiki.ihep.ac.cn/pub/HXMT/GRBList/HEB201221591_lc.jpg 

All measurements above are made with the CsI detectors operating in the 
regular mode with the energy range of about 80-800 keV (deposited energy). 
Only gamma-rays with energy greater than about 200 keV can penetrate 
the spacecraft and leave signals in the CsI detectors installed inside 
of the telescope. 
 
Insight-HXMT is the first Chinese space X-ray telescope, which was 
funded jointly by the China National Space Administration (CNSA) and 
the Chinese Academy of Sciences (CAS). 
More information about it could be found at: 
http://www.hxmt.org.


GRB_name: GRB201221D
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29148
SUBJECT: GRB 201221D: 3.6m DOT optical observations
DATE:    20/12/23 12:27:46 GMT
FROM:    Rahul Gupta at ARIES, India  <rahulbhu.c157@gmail.com>

Dimple (ARIES), A. Panchal (ARIES), A. Gangopadhyay (ARIES), A. Ghosh
(ARIES), R. Gupta (ARIES), A. Kumar (ARIES), K. Misra (ARIES), and S. B.
Pandey (ARIES) report:

We carried out the follow-up observations of GRB 201221D (Page et al., GCN
29112) with Aries Devasthal Faint Object Spectrograph and Camera (ADFOSC)
mounted on the 3.6m Devasthal Optical Telescope (DOT) at Devasthal
observatory of Aryabhatta Research Institute of observational sciencES
(ARIES), India. The observations were started on 2020-12-22 at 23:10:00 UT.
We observed a series of 4 images with the exposure time of 900 seconds each
in r-band. At the position reported by Malesani et al., (GCN 29117), we
detect an uncatalogued source in r-band with a magnitude of 23.46 +- 0.09
(AB mag), calibrated with the nearby PanSTARRS field. However, we remark
that this is an extended source and may contain significant host galaxy
contribution. For further verification, host galaxy subtraction is highly
encouraged.

The magnitude is not corrected for the Galactic extinction in the direction
of the burst.

This circular may be cited.


GRB_name: GRB201221A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29149
SUBJECT: GRB 201221A: REM early-time afterglow detection
DATE:    20/12/23 14:46:01 GMT
FROM:    Paolo D'Avanzo at INAF-OAB  <pda.davanzo@gmail.com>

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

We observed the field of GRB 201221A (Page et al., GCN Circ. 29096) with the REM 60cm robotic 
telescope located at the ESO premise of La Silla (Chile). The observations were performed starting 
on 2020 December 21 at 07:10:33 UT (i.e. 92 seconds after the burst) and were carried in the g, r, i, z 
bands simultaneously. 

From preliminary photometry, we estimate the following magnitudes and 3sigma upper limits for the 
afterglow reported by Malesani et al. (GCN Circ. 29100):

g > 17.9
r > 17.8
i > 17.7
z = 15.8 +/- 0.3

(AB; calibrated against the APASS catalogues), at a mean time of 97 seconds after the GRB t0. 
By combining our z-band magnitude with the one reported by Malesani et al., we infer an afterglow 
temporal decay (f propto t^(alpha)) of alpha ~ -1.2 between 97 seconds and 2100 seconds after the GRB t0. 


GRB_name: GRB201221A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29150
SUBJECT: GRB 201221A: Konus-Wind detection and joint Konus-Wind + Swift-BAT spectral analysis
DATE:    20/12/23 15:51:43 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

D. Frederiks, S. Golenetskii, R.Aptekar, A. Kozlova, A.Lysenko,
D. Svinkin, A. Tsvetkova,  M. Ulanov, T. Cline, on behalf of the Konus-Wind team,
and A. Lien (GSFC/UMBC), report:

The long GRB 201221A (Swift-BAT trigger #1013852, T0 = T0(BAT)= 07:09:01.4258 UT:
Page et al., GCN 29096; Breadmore et al., GCN 29108;
Fermi GBM Sub-Threshold Detection: Veres, GCN 29110, 29111)
was detected by Konus-Wind (KW) in the waiting mode.

A Bayesian block analysis of the KW waiting mode data in the 20-400 keV band
reveals a ~11 sigma count rate increase over background in the interval
from ~T0(BAT)-10 s to ~T0(BAT)+20 s.
The KW light curve of this burst is available
at http://www.ioffe.ru/LEA/GRBs/GRB201221A/

To derive the broad-band spectral parameters of this burst, we performed
a joint spectral analysis of the Swift/BAT data (15-150 keV) and the Konus-Wind
3-channel spectral data, which cover the energy range from ~20 keV to ~1.5 MeV.

The time-averaged spectrum, measured from T0(BAT)-9.6 s to T0(BAT)+19.8 s,
is best fit in the 15 keV - 1.5 MeV range by the GRB (Band)
function with the following model parameters:
the low-energy photon index alpha = -0.95 (-0.22,+0.31),
the high energy photon index beta = -2.39 (-0.89,+0.38),
and the peak energy Ep = 194 (-63,+81) keV, chi2 = 65/58 dof.

In the 15-1500 keV band, the total burst fluence S is 4.3(-0.4, + 0.7)x10^-6 erg/cm^2,
and the 2.944 s peak energy flux Fp is 2.0 (-0.2, + 0.3)x10^-7 erg/cm^2.
In the 10-10000 keV band, standard for the KW analysis, S = 5.3(-1.0, + 2.3)x10^-6 erg/cm^2
and Fp = 2.4 (-0.4, + 1.0)x10^-7 erg/cm^2.

Assuming the redshift z=5.70 (Malesani et al., GCN 29100)
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 3.0(-0.5,+1.3)x10^53 erg,
the isotropic luminosity L_iso to 9.0(-1.6,+3.9)x10^52 erg/s,
and the rest-frame peak energy of the time-integrated spectrum Ep,z to 1300(-420,+540) keV.
With these values, GRB 201221A is within 90% prediction bands
for both 'Amati' and 'Yonetoku' relations for the sample of >300 long KW GRBs
with known redshifts (part I: Tsvetkova et al., ApJ 850 161, 2017;
part II: Tsvetkova et al., ApJ, accepted),
see http://www.ioffe.ru/LEA/GRBs/GRB201221A/GRB201221A_rest_frame.pdf

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


GRB_name: GRB201223A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29158
SUBJECT: GRB 201223A: Swift detection of a burst with a bright optical counterpart
DATE:    20/12/23 18:12:13 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

J.D. Gropp (PSU), S. D. Barthelmy (GSFC), J. A. Kennea (PSU),
N. J. Klingler (PSU), F. E. Marshall (NASA/GSFC),
K. L. Page (U Leicester), D. M. Palmer (LANL), B. Sbarufatti (PSU) and
M. H. Siegel (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 17:58:26 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 201223A (trigger=1014316).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 132.849, +71.174 which is 
   RA(J2000) = 08h 51m 24s
   Dec(J2000) = +71d 10' 26"
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 50 sec.  The peak count rate
was ~1600 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 17:59:40.7 UT, 73.7 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source located at RA, Dec 132.78615, 71.17926 which
is equivalent to:
   RA(J2000)  = 08h 51m 08.68s
   Dec(J2000) = +71d 10' 45.3"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 75 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 3.13
x 10^20 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 78 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  = 08:51:09.51 = 132.78963
  DEC(J2000) = +71:10:47.4  =  71.17982
with a 90%-confidence error radius of about 0.61 arc sec. This position is 3.8
arc sec. from the center of the XRT error circle. The estimated magnitude is
16.16 with a 1-sigma error of about  0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.05. 

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: GRB201223A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29159
SUBJECT: GRB 201223A: Nanshan/NEXT early optical afterglow detection
DATE:    20/12/23 18:58:50 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

Z.P. Zhu (NAOC, HUST), S.Y. Fu, M. Zhang, X. Liu, D. Xu (NAOC), X. Gao (Urumqi 
No.1 Senior High School), J.Z. Liu (XAO) report:

We observed the field of GRB 201223A (Gropp et al., GCN 29158) using the 
NEXT-0.6m optical telescope located at Nanshan, Xinjiang, China. 
Observations automatically started at 18:01:14 UT on 2020-12-23, i.e., 
168 s after the BAT trigger. We obtained a series of 2x40s, 4x60s and 
12x90s frames in the Sloan r-filter, and observations are ongoing.

An uncatalogued decaying optical transient is detected at the Swift/UVOT 
position (Gropp et al., GCN 29158), which is thus concluded to be the 
optical afterglow of burst. The afterglow has r = 15.67 +/- 0.01 mag in 
our first image, calibrated with nearby PS1 stars.

[GCN OPS NOTE(24Dec2020)  Per author's request, M. Zhang was added
to the author list.]


GRB_name: GRB201223A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29160
SUBJECT: GRB 201223A: BOOTES-4/MET early optical observation
DATE:    20/12/23 19:05:41 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

Y.-D. Hu, E. Fernandez-Garcia, M. A. Castro, A. J. Castro-Tirado (IAA-CSIC), C. Perez del Pulgar, A. Castellon, I. Carrasco (Univ. de Malaga), S. Guziy (Univ. of Nikolaev) and D. Xiong, Y. Fan, X. Zhao, J. Bai, C. Wang, Y. Xin (Yunnan Nacional Astronomical Observatory) on behalf of a larger collaboration, report:

Following the detection of GRB 201223A by Swift (Gropp et al. GCNC 29158), the 0.6m BOOTES-4/MET robotic telescope at Lijiang Astronomical
Observatory (China) started to gather images in clear filter starting at 18:01:22 UT (~176 s after trigger). The optical afterglow reported by Swift/UVOT (Gropp et al. GCNC 29158), MASTER (Lipunov et al. GCNC 29157) and Nanshan/NEXT (Zhu et al. GCNC 29159) is detected with a magnitude of 15.7+-0.15. Additional observations are ongoing.

We thank the staff at Lijiang observatory for their excellent support.


GRB_name: GRB201223A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29161
SUBJECT: GRB 201223A: Fermi GBM Detection
DATE:    20/12/23 23:53:30 GMT
FROM:    Joshua Wood at MSFC/Fermi-GBM  <joshua.r.wood@nasa.gov>

J. Wood (NASA/MSFC) reports on behalf of the Fermi GBM Team:

"At 17:58:25.69 UT on 23 December 2020, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 201223A (trigger 630439110 / 201223749)
which was also detected by the Swift/BAT and Swift/XRT
(Gropp et al. 2020, GCN 29158). The GBM
on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 63 degrees.

The GBM light curve shows multiple peaks
with a duration (T90) of about 33 s (50-300 keV).
The time-averaged spectrum from T0-17 s to T0+13 s is
best fit by a Band function with Epeak = 86 +/- 12 keV, 
alpha = 0.14 +/- 0.38 and beta = -2.6 +/- 0.4.
A power law function with an exponential
high-energy cutoff fits the spectrum equally well.
The power law index is -0.14 +/- 0.24 and
the cutoff energy, parameterized as Epeak, is 99 +/- 8 keV.

The event fluence (10-1000 keV) in this time interval is
(2.1 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+4.1 s in the 10-1000 keV band
is 2.4 +/- 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: GRB201223A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29163
SUBJECT: GRB 201223A: Swift-BAT refined analysis
DATE:    20/12/24 01:56:53 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

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

Using the data set from T-239 to T+882 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 201223A (trigger #1014316)
(Gropp et al., GCN Circ. 29158).  The BAT ground-calculated position is
RA, Dec = 132.735, 71.176 deg which is
   RA(J2000)  =  08h 50m 56.3s
   Dec(J2000) = +71d 10' 34.9"
with an uncertainty of 1.4 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 53%.

The mask-weighted light curve shows a multi-peaked structure that
starts at ~T-25 s and ends at ~T+8 s. The main peak occurs at ~T0.
T90 (15-350 keV) is 29.0 +- 6.7 sec (estimated error including
systematics).

The time-averaged spectrum from T-25.18 to T+7.82 sec is best fit
by a simple power-law model.  The power law index of the time-averaged
spectrum is 1.35 +- 0.13.  The fluence in the 15-150 keV band is
1.3 +- 0.1 x 10^-06 erg/cm2. The 1-sec peak photon flux measured from
T-0.18 sec in the 15-150 keV band is 1.5 +- 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/1014316/BA/


GRB_name: GRB201223A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29164
SUBJECT: GRB 201223A: MITSuME Akeno optical observation
DATE:    20/12/24 02:08:01 GMT
FROM:    Ryohei Hosokawa at Tokyo Institute of Technology  <hosokawa@hp.phys.titech.ac.jp>

R. Hosokawa, K. L. Murata, R. Adachi, M. Niwano, F. Ogawa, N.
Nakamura, N. Ito, S. Ogata, H. Takamatsu, H. Hara, Y. Yatsu, and N.
Kawai (TokyoTech) report on behalf of the MITSuME collaboration:

We observed the field of GRB 201223A (J.D. Gropp et al., GCN #29158,
J. Wood et al., GCN #29161) with
the optical three color (g', Rc, and Ic) CCD cameras attached to the
MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan.
The observation started at 2020-12-23 17:59:18 UT (52s after Swift BAT
trigger). We detected the point source at the position consistent with
the afterglow detected previously (Lipunov et al. GCN #29157, Gropp et
al., GCN #29158, Z.P. Zhu
et al. GCN #29159, Y.-D. Hu et al. GCN #29160).
We measured the magnitudes as follows.

T0+[sec] MID-UT T-EXP[sec] measured magnitudes
------------------------------------------------------------------------------------------------
52 17:59:48 60 g'=15.45+/-0.05, Rc=15.04+/-0.03, Ic=14.77+/-0.04
------------------------------------------------------------------------------------------------
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.,
https://doi.org/10.1093/pasj/psaa091,
https://arxiv.org/abs/2008.11486; https://github.com/MNiwano/Eclaire).


GRB_name: GRB201223A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29165
SUBJECT: GRB 201223A: iTelescope optical afterglow observations
DATE:    20/12/24 02:49:44 GMT
FROM:    Filipp Dmitrievich Romanov at Amateur astronomer  <filipp.romanov.27.04.1997@gmail.com>

I observed the field of GRB 201223A (Gropp et al., GCN Circ. 29158)
with remote telescope T18 (0.32-m f/8.0 reflector + CCD) of
iTelescope.Net in observatory AstroCamp at Nerpio (Spain) on
2020-12-23 since 19:49:22 UT (1 hour 50 minutes 56 seconds after the
trigger). 5 images (with exposures 300, 120 and 180 seconds) were
obtained with Astrodon luminance filter and 4 images (exposures: 300
and 60 seconds) with photometric Johnson V filter. I detected the
optical afterglow in images with position: RA 08:51:09.46 Dec
+71:10:47.00. It is not present in the Pan-STARRS images.

The following magnitudes were measured from comparison to r magnitudes
of nearby stars from Pan-STARRS DR1 catalogue (Chambers et al., 2016):

Time of start (UT)  Exp.time (s.)  Bin.  Mag. r   Mag. error    Filter
---------------------------------------------------------------------------
19:49:22            300            1     19.2     0.2           Luminance
19:56:25            300            1     19.3     0.4           V
20:26:25            300            2     19.9     0.4           V
20:33:07            300            2     20.1     0.3           Luminance
---------------------------------------------------------------------------

Magnitudes were not corrected for Galactic extinction.

Stacked image (4x300 + 2x120 + 180 sec.) available here:
https://www.flickr.com/photos/filipp-romanov/50753199496


GRB_name: GRB201223A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29166
SUBJECT: GRB 201223A: GWAC-F60A optical afterglow observations
DATE:    20/12/24 06:56:16 GMT
FROM:    Liping Xin at NAOC, SVOM  <xlp@nao.cas.cn>

L. P. Xin(NAOC),  L. H. Li(NAOC), X. H. Han(NAOC), J. Y. Wei(NAOC),  J. Wang(GXU),  
C. Wu(NAOC),  X. G. Wang(GXU), E. W. Liang (GXU), Y. L. Qiu(NAOC), and J. S. Deng(NAOC) report:

We began to observe GRB 201223A (Gropp et al., GCN #29158, 
Wood et al., GCN #29161) with Xinglong GWAC-F60A telescope, China, 
at 17:59:10.1 (UT), 23th. Dec. 2020, about 44 sec after the burst.

A series of  R, I, and B band images were obtained.
The optical afterglow reported by (Lipunov et al., GCN #29157; Gropp et
al., GCN #29158; Zhu et al., GCN #29159; Hu et al.ï¼ŒGCN #29160;
Hosokawa et al., GCN #29164; Filipp Dmitrievich Romanov GCN #29165)
was clear detected in our images. 

The brightness is fading from 15.0 mag to 18.8 mag  in R band
during about 100 sec to 10000 sec after the burst. 
 
The R-band brightness is calibrated to the USNO B1.0 catalog,
(RA=08:50:21.447, DEC=+71:12:12.80, J2000, R2=9.92)

More analysis are still continuing.

The message may be cited.


GRB_name: GRB201223A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29167
SUBJECT: GRB 201223A: Mondy and Kitab optical observations
DATE:    20/12/24 13:09:08 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI),  A. Pozanenko (IKI), N. Pankov (HSE),  E. Klunko 
(ISTP), A. Novichonok (Petrozavodsk State University, KIAM), Sh. 
Ehgamberdiev (UBAI) report on behalf of IKI-GRB-FuN:

We observed the field of  GRB 201223A (Gropp et al., GCN 29158) with 
AZT-33IK telescope of Sayan observatory (Mondy) starting on Dec. 23 (UT) 
  18:29:01 and Kitab-ISON RC-36  telescope starting (UT) 19:25:57. The 
optical transient (Lipunov  et al. GCN 29157; Gropp et al., GCN 29158; 
Zhu et al. GCN 29159; Hu et al. GCN 29160; Hosokawa  et al. GCN 29164; 
Romanov et al. GCN 29165; Xin et al. GCN 29166) is detected in our 
stacked images in R-filter.

Preliminary photometry of the optical transient in a combined images is 
following

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

2020-12-23 18:29:01   0.05943 R      10*120  18.95 0.23  19.5 AZT-33IK
2020-12-23 18:29:01   0.05943 R      55*120  19.38 0.09  22.1 AZT-33IK
2020-12-23 19:25:57   0.08161 R      60*60   19.40 0.20  19.6 RC-36

The photometry is based on the nearby USNO-B1.0 stars
USNO-B1.0_id R2
1611-0080890 18.64
1612-0081305 18.44


GRB_name: GRB201223A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29168
SUBJECT: GRB 201223A: GROWTH-India Telescope (GIT) photometric follow-up.
DATE:    20/12/24 14:21:13 GMT
FROM:    Harsh Kumar at Indian Inst of Tech,Bombay  <harshkosli13@gmail.com>

H. Kumar (IITB), U. Stanzin (IAO), V. Bhalerao (IITB), G. C. Anupama (IIA),
S. Barway (IIA), report on behalf of the GROWTH-India collaboration:

We observed GRB 201223A detected by Swift-BAT (J.D. Gropp et al., GCN
#29158); optical counterpart first reported by V. Lipunov et al., (GCN
#29157) with 0.7m GROWTH-India Telescope, starting at
2020-12-23T18:30:33.51 UT. We obtained multiple images of 300 sec each in
the r' filter. We clearly detected the afterglow at a position consistent
with Swift-UVOT (GCN #29158) and MASTER-Net OT (GCN #29157) positions.

We obtained the following photometric results:

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

 JD (start) | T_start-T0 (hrs) | Filter | Mag (AB)|

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

2459207.27122 | 0.5 | r' | 18.52 +/- 0.03

2459207.28623 | 0.9 | r' | 19.12 +/- 0.04

2459207.32568 | 1.8 | r' | 19.98 +/- 0.09

2459207.34029 | 2.2 | r' | 20.15 +/- 0.09

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

Combining our photometric results with r band measurements of Z.P. Zhu et.
al., (GCN #29159), we conclude that the source is fading with a power-law
index of 1.04 +/- 0.01. The magnitudes are calibrated against PanSTARRs PS1
data release, (Flewelling et al., 2018) and not corrected for galactic
extinction. Processing of more data is underway.

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 and the
Indian Institute of Technology Bombay with support from the Indo-US Science
and Technology Forum (IUSSTF) and the Science and Engineering Research
Board (SERB) of the Department of Science and Technology (DST), Government
of India (https://sites.google.com/view/growthindia/). It is located at the
Indian Astronomical Observatory (Hanle), operated by the Indian Institute
of Astrophysics (IIA).


GRB_name: GRB201223A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29169
SUBJECT: GRB 201223A: NOT optical upper limit and NEXT powerlaw decay
DATE:    20/12/24 14:29:07 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

D. Xu (NAOC), D. B. Malesani (DTU Space), P. Galindo (NOT), Z.P. Zhu 
(NAOC, HUST), D. A. Kann (HETH/IAA-CSIC), report on behalf of a larger 
collaboration:

We observed the field of GRB 201223A (Gropp et al., GCN 29158) using the 
2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera. 
We obtained 2x120s Sloan r-band frames starting at 02:21:52 UT on 
2020-12-24, i.e., 8.4 hr after the BAT trigger.

The previously reported optical afterglow (Lipunov et al. GCN 29157; 
Gropp et al., GCN 29158; Zhu et al. GCN 29159; Hu et al. GCN 29160; 
Hosokawa et al. GCN 29164; Romanov et al. GCN 29165; Xin et al. GCN 
29166; Belkin et al., GCN 29167; Kumar et al., GCN 29168) is not 
detected in the stacked image, down to a limiting magnitude of r > 22.0 mag.

Further analysis of our previous NEXT observations (Zhu et al. GCN 
29159) shows that the afterglow is decaying as F_rband ~ t^(-\alpha), 
where \alpha = 1.1 since the very beginning. The afterglow would be 
slightly fainter than 22.0 mag if this powerlaw decay is extrapolated 
until the NOT observational time, being consistent with the observed NOT 
upper limit. So the afterglow could be decaying in a single powerlaw 
until the NOT observation or have broken to a steeper decay before the 
NOT observation.


GRB_name: GRB201223A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29170
SUBJECT: GRB 201223A: Enhanced Swift-XRT position
DATE:    20/12/24 14:52:52 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 1078 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 201223A, 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 = 132.79017, +71.17923 which is equivalent
to:

RA (J2000): 08h 51m 9.64s
Dec (J2000): +71d 10' 45.2"

with an uncertainty of 1.8 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: GRB201223A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29171
SUBJECT: GRB 201223A: Swift-XRT refined Analysis
DATE:    20/12/24 15:18:33 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.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), B.
Sbarufatti (PSU), J.P. Osborne (U. Leicester), 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 8.0 ks of XRT data for GRB 201223A (Gropp et al. GCN
Circ. 29158), from 81 s to 18.2 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. 29170).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.82 (+/-0.04).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.87 (+0.18, -0.13). The
best-fitting absorption column is  4.1 (+4.0, -0.9) x 10^20 cm^-2,
consistent with the Galactic value of 3.1 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 3.5 x 10^-11 (2.8 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      4.1 (+4.0, -0.9) x 10^20 cm^-2
Galactic foreground: 3.1 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.87 (+0.18, -0.13)

If the light curve continues to decay with a power-law decay index of
0.82, the count rate at T+24 hours will be 5.7 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 2.0 x
10^-13 (1.6 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/01014316.

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


GRB_name: GRB201223A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29173
SUBJECT: GRB 201223A: 1.3m DFOT and 1.04m ST optical observations
DATE:    20/12/24 17:09:51 GMT
FROM:    Rahul Gupta at ARIES, India  <rahulbhu.c157@gmail.com>

Rahul Gupta (ARIES), Dimple (ARIES), Amit Kumar (ARIES), Vineet Ojha
(ARIES), Ankur Ghosh (ARIES), Amar Aryan (ARIES),  Shashi B. Pandey
(ARIES), and Kuntal Misra (ARIES) report:

We observed the optical afterglow ( Lipunov et al., GCN 29157; Gropp
et al., GCN 29158; Zhu et al., GCN 29159; Hu et al., GCN 29160;
Hosokawa et al., GCN 29164; Romanov et al., GCN 29165; Xin et al., GCN
29166; Belkin et al., GCN 29167; and Kumar et al., GCN 29168) of Swift
and Fermi detected GRB 201223A (Gropp et al., GCN 29158; and Wood et
al., GCN 29161) using the 1.3m Devasthal Fast Optical Telescope (DFOT)
and 1.04m Sampurnanand Telescope (ST) of Aryabhatta Research Institute
of Observational Sciences (ARIES), India. The observations were
started on 2020-12-23 at 19:01:46 UT. Multiple frames having an
exposure time of 300 s were taken in the I filter using DFOT and in
BVRI filters using ST. We clearly detected the optical counterpart at
the position reported by Gropp et al., GCN 29158.


The preliminary photometric estimate of the afterglow using I band
data of DFOT is the following :


Date Start_UT           T_start-T0 (hrs)      Filter      Exp time (s)
  Magnitude    Mag_err
------------------------------ ------------------------------
------------------------------ ------------------------------

2020-12-23   19:07:55      1.158              I              300*1
          18.71           0.04

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


The magnitude is not corrected for the Galactic and Host extinction in
the direction of the burst. Photometric calibration is performed using
the standard stars from the USNO-B1.0 catalogue.  Further processing
of data is going on.

This circular may be cited.


GRB_name: GRB201223A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29174
SUBJECT: GRB 201223A: AbAO optical observations
DATE:    20/12/24 21:31:45 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We observed the field of  GRB 201223A (Gropp et al., GCN 29158;  Wood et
al., GCN 29161) with AS-32 telescope of Abastumani observatory (AbAO) in 
R-filter. The optical afterglow (Lipunov et al., GCN 29157; Gropp
et al., GCN 29158; Zhu et al., GCN 29159; Hu et al., GCN 29160;
Hosokawa et al., GCN 29164; Romanov et al., GCN 29165; Xin et al., GCN
29166; Belkin et al., GCN 29167; Kumar et al., GCN 29168; Xu et al., GCN 
29169; Gupta et al., GCN 29173) is detected in stacked images.

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


2020-12-23 19:39:59   0.0733  R      8*60   19.38  0.17  19.8
2020-12-23 21:19:22   0.1517  R     35*60   20.28  0.13  20.9

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


GRB_name: GRB201223A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29176
SUBJECT: GRB 201223A: HCT optical upper limit
DATE:    20/12/26 05:51:35 GMT
FROM:    Harsh Kumar at Indian Inst of Tech,Bombay  <harshkosli13@gmail.com>

H. Kumar(IITB), D. K. Sahu (IIA), V. Bhalerao(IITB), G. C. Anupama(IIA), S.
Barway(IIA) report on behalf of the HCT team:

We observed GRB 201223A detected by Swift-BAT (J.D. Gropp et al., GCN
#29158); optical counterpart first reported by V. Lipunov et al., (GCN
#29157) with 2.0m Himalayan Chandra Telescope (HCT). We obtained a series
of 180-sec exposures in the Bessell R filter and did not detect the
afterglow in our stacked image. We obtained the following upper limit:

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

JD (mid) | T_mid-T0(hrs) | Exposure | Filter | Lim_mag (5-sigma) |

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

2459208.4569 | 28.99 | 180*10 (stacked) | Bessell R | > 22.49 |

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

Our upper limit is consistent with power-law decay extrapolation suggested
by D. Xu et al., (GCN #29169), Kumar et al., (GCN #29168).


These observations were carried out under the ToO program "HCT-2020-C3-P6".
We thank HCT staff for undertaking the observations.


GRB_name: GRB201223A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29177
SUBJECT: GRB 201223A: Swift/UVOT Detection
DATE:    20/12/26 22:03:09 GMT
FROM:    Alexander Belles at PSU/Swift  <aub1461@psu.edu>

â€‹A. Belles (PSU) and J. D. Gropp (PSU)

report on behalf of the Swift/UVOT team:



The Swift/UVOT began settled observations of the field of GRB 201223A

79 s after the BAT trigger (Gropp et al., GCN Circ. 29158).

A source consistent with the XRT position (Goad et al., GCN Circ. 29170)

is detected in the initial UVOT exposures.



The preliminary UVOT position is:

    RA  (J2000) =  08:51:09.51 = 132.78961 (deg.)

    Dec (J2000) = +71:10:47.4  =  71.17984 (deg.)

with an estimated uncertainty of 0.42 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          79             229            147      16.06+/-0.03

white               571           1019            186      18.04+/-0.08

white             5921           6121            196           >20.17

white           12121         12630            497      20.09+/-0.30

v                      621           1069              58           >17.44

b                      547           1167              58      17.97+/-0.25

b                  11208         12115            885           >20.38

u_FC               292             541            246      16.75 +/- 0.04

u                      694           1142              38           >17.58

w1                   670           1118              58           >17.65

m2                   645           1093              58           >17.87

w2                   596           1045              58           >17.81



The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.04 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB201227A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29179
SUBJECT: GRB 201227A: AGILE detection of a burst
DATE:    20/12/27 19:57:36 GMT
FROM:    Francesco Longo at U of Trieste,INFN Trieste  <franzlongo1969@gmail.com>

A. Ursi (INAF/IAPS), F. Verrecchia, C. Pittori (SSDC, and INAF/OAR),
F. Longo (Univ. Trieste and INFN Trieste), M. Tavani (INAF/IAPS, and
Univ. Roma Tor Vergata), A. Argan, M. Cardillo, C. Casentini, Y.Evangelista,
G. Piano (INAF/IAPS),  F. Lucarelli (SSDC, and INAF/OAR), A. Bulgarelli,
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), A. Giuliani (INAF/IASF-Mi),
report on behalf of the AGILE Team:

The AGILE Mini-CALorimeter (MCAL) detected a short burst at
T0 = 2020-12-27 15:14:07.40 +/- 0.01 s (UTC) detected also by
Fermi/GBM (trigger 630774852).

The event lasted about 0.10 s and released a total number of ~480 counts
in the detector (in the 0.4-100 MeV energy range),
above an average background rate of 676 counts / s.

The light curve shows a single sharp peak and can be found at
http://www.agilescienceapp.it/notices/GRB_071058_536166847.405605.png.

The AGILE-MCAL detector is a CsI detector with a 4 pi FoV,
sensitive in the energy range 0.4-100 MeV.

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: GRB201223A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29180
SUBJECT: GRB 201223A: AROMA-N Optical Observation
DATE:    20/12/27 22:15:11 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

M. Nakamura, K. Hasuda, T. Sakamoto (AGU)

We observed the field of GRB 201223A detected by Swift
(Gropp et al., GCN Circ. 29158) with the 14-inch AGU Robotic
Optical Monitor for Astrophysical object - Narrow (AROMA-N)
located at the Sagamihara campus of Aoyama Gakuin University.
58 images of 60 sec exposures were taken in the R filter
starting from December 23 18:04:02 (UT) about 5.6 minutes
after the trigger and stopped on December 23 19:16:09 (UT).
We do not detect the optical afterglow both in the individual
images and the stacked image.  The estimated five sigma
upper limit of the combined image (total exposure of 3480 sec)
is ~17.3 mag using the USNO-B1 catalog.


GRB_name: GRB201103B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29181
SUBJECT: ZTF20acozryr/AT2020yxz (GRB 201103B): Maidanak optical observations
DATE:    20/12/28 00:05:21 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI), A. Pozanenko (IKI), O. Burhonov (UBAI), R. Ya. 
Inasaridze (AbAO), P. Levkina (INASAN), N. Pankov (HSE, IKI), A. Volnova 
(IKI), Sh. Ehgamberdiev (UBAI)  report on behalf of GRB IKI FuN:

We finished observations of the ZTF20acozryr/AT2020yxz (Coughlin et al., 
GCN  28841)  with AZT-22 telescope of Maidanak observatory, AS-32 
telescope of Abastumani observatory, and Zeiss-2000 telescope of Terskol 
observatory.  The optical transient (Coughlin et al., GCN  28841; Xu  et 
al., GCN 28846; Zhu et al., GCN 28854; Mao et al., GCN  28861; Belkin et 
al., GCNs 28862, 28875, 28883, 28886;  Mao et al., GCN 28863; Kumar et 
al., GCN 28876; Paek  et al., GCN 28880; Moskvitin et al., GCN 28926) at 
redshift  z = 1.105 (Xu et al., GCN 28847) associated with afterglow of 
GRB 201103B (Ursi et al., GCN 28831; Svinkin et al., GCN 28844; Evans et 
al., GCN 28858).

The photometry reported early in Volnova  et al., GCN 28925 must 
corrected the GCN 28886. We apologize for inconvenience and thank to 
D.A. Kann who pointed out for typo in the GCN 28925.
We repeat corrected photometry of our CrAO/ZTSh optical observation on 
2020-11-13 22:58:04 below. We also add photometry of positive detections 
and meaningful upper limit. the photometry below is still preliminary. 
The photometry is based on the same reference stars of USNO-B1.0 stars.

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

2020-11-12 20:20:48  9.12087    R  80*60   21.70 0.35   21.7 AS-32
2020-11-13 22:58:04 10.21897    R  24*120  22.45 0.14   23.6 ZTSh
2020-11-23 19:29:37 12.07213    R  14*180  22.80 0.13   24.1 AZT-22
2020-11-23 19:26:37 20.08671    R  30*180  n/d   n/d    23.2 AZT-22

A full light curve and upper limits obtained in our observations 
(R-filter) can be found in

http://grb.rssi.ru/GRB201103B/GRB201103B_LC_R.png

A typical power law  light curve (index of ~1.12) can be suggested based 
on our observations and photometry gathered from  GCNs, see

http://grb.rssi.ru/GRB201103B/GRB201103B_LC_GCN.png

One can suggest overlay bumps (or plateau) on  the light curve of at 2-3 
days, and 5-9 days after burst trigger.

If we extrapolate the power law curve backward to the 200 seconds the 
afterglow brightness could have ~12m. If so, one can look for data in 
all sky cameras or wide field surveys to search early phase of the 
afterglow of the GRB 201103B (trigger time (UT) 2020-11-03 18:06:45.36, 
Ursi et al., GCN 28831).


GRB_name: GRB201227A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29182
SUBJECT: IPN triangulation of GRB 201227A (short)
DATE:    20/12/28 01:07:52 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

K. Hurley, on behalf of the IPN,

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

A. Ursi, N. Parmiggiani, F. Verrecchia, A. Bulgarelli,
A. Trois, M. Marisaldi, C. Pittori, M. Tavani, Y. Evangelista,
I. Donnarumma, M. Cardillo, G. Piano, G. Minervini, A. Argan,
F. Lucarelli, A. Zoli, V. Fioretti, F. Fuschino, M. Pilia,
F. Longo, A. Giuliani on behalf of the AGILE team, report:

The short-duration, very bright GRB 201227A
(AGILE detection: Ursi et al., GCN Circ. 29179)
has been detected by Fermi (GBM trigger 630774852), Konus-Wind,
INTEGRAL (SPI-ACS), AGILE (MCAL), and Swift (BAT), so far,
at about 54847 s UT (15:14:07).
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:
   170.121 (11h 20m 29s) -73.613 (-73d 36' 48")
  Corners:
   171.971 (11h 27m 53s) -73.140 (-73d 08' 22")
   171.755 (11h 27m 01s) -73.060 (-73d 03' 36")
   168.169 (11h 12m 41s) -74.071 (-74d 04' 16")
   168.379 (11h 13m 31s) -74.155 (-74d 09' 17")
  ---------------------------------------------
The error box area is 517 sq. arcmin, and its maximum
dimension is 1.45 deg (the minimum one is 6 arcmin).
The Sun distance was 72 deg.

This box may be improved.

The Swift ToO has been submitted.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB201227_T54847/IPN/

The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.


GRB_name: GRB201228A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29183
SUBJECT: GRB 201228A: Fermi GBM Final Real-time Localization
DATE:    20/12/28 02:37:48 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 02:27:30 UT on 28 Dec 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 201228A (trigger 630815255.731822 / 201228102).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 303.4, Dec = 32.3 (J2000 degrees, equivalent to J2000 20h 13m, 32d 17'), with a statistical uncertainty of 15.4 degrees.

The angle from the Fermi LAT boresight is 44.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201228102/quicklook/glg_skymap_all_bn201228102.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201228102/quicklook/glg_healpix_all_bn201228102.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201228102/quicklook/glg_lc_medres34_bn201228102.gif


GRB_name: GRB201227A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29184
SUBJECT: GRB 201227A: Swift ToO observations
DATE:    20/12/28 05:18:20 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 IPN GRB 201227A. 
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021409

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 IPN 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: GRB201227A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29185
SUBJECT: GRB 201227A: Tiled Swift observations
DATE:    20/12/28 05:35:59 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 series of observations, tiled on the sky, of the
IPN GRB 201227A. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00096

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the IPN event is high: 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: GRB201226A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29186
SUBJECT: GRB 201226A: Insight-HXMT/HE detection
DATE:    20/12/28 14:59:46 GMT
FROM:    Shuo Xiao at IHEP  <xiaoshuo@ihep.ac.cn>

S. Xiao, C. Cai, Y. F. Du, Y. G. Zheng, Q. Luo, Q. B. Yi, 
Y. Huang, C. K. Li, G. Li, X. B. Li, J. Y. Liao, S. L. Xiong,
C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, A. M. Zhang, 
Y. F. Zhang, X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, 
Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, 
M. Wu, Y. P. Xu, S. N. Zhang (IHEP), 
report on behalf of the Insight-HXMT team:

At 2020-12-26T13:16:26.60 (T0), Insight-HXMT/HE detected 
GRB 201226A (trigger ID: HEB201226553) in a routine search of the data, 
which also triggered Fermi/GBM (trigger 630681391).

The Insight-HXMT/HE light curve mainly consists of multiple 
pulses with a duration (T90) of 69.119 s measured from T0+0.34 s. 
The 1-ms peak rate, measured from T0+69.194 s, is 706 cnts/sec. 
The total counts from this burst is 10857 counts. 
URL_LC: http://twiki.ihep.ac.cn/pub/HXMT/GRBList/HEB201226553_lc.jpg 

All measurements above are made with the CsI detectors operating in the 
regular mode with the energy range of about 80-800 keV (deposited energy). 
Only gamma-rays with energy greater than about 200 keV can penetrate 
the spacecraft and leave signals in the CsI detectors installed inside 
of the telescope. 
 
Insight-HXMT is the first Chinese space X-ray telescope, which was 
funded jointly by the China National Space Administration (CNSA) and 
the Chinese Academy of Sciences (CAS). 
More information about it could be found at: 
http://www.hxmt.org.


GRB_name: GRB201227A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29187
SUBJECT: GRB 201227A: Insight-HXMT/HE detection
DATE:    20/12/28 15:00:13 GMT
FROM:    Shuo Xiao at IHEP  <xiaoshuo@ihep.ac.cn>

S. Xiao, C. Cai, Y. F. Du, Y. G. Zheng, Q. Luo, Q. B. Yi, 
Y. Huang, C. K. Li, G. Li, X. B. Li, J. Y. Liao, S. L. Xiong,
C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, A. M. Zhang, 
Y. F. Zhang, X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, 
Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, 
M. Wu, Y. P. Xu, S. N. Zhang (IHEP), 
report on behalf of the Insight-HXMT team:

At 2020-12-27T15:14:07.400 (T0), Insight-HXMT/HE detected 
GRB 201227A (trigger ID: HEB201227634) in a routine search of the data, 
which also triggered Fermi/GBM (trigger 630774852) and 
AGILE Mini-CALorimeter (GCN#29179).

The Insight-HXMT/HE light curve mainly consists of multiple 
pulses with a duration (T90) of 0.098 s measured from T0-0.03 s. 
The 1-ms peak rate, measured from T0+0.024 s, is 52740 cnts/sec. 
The total counts from this burst is 1612 counts. 
URL_LC: http://twiki.ihep.ac.cn/pub/HXMT/GRBList/HEB201227634_lc.jpg 

The HE light curves have not been corrected for data saturation
caused by the extreme brightness of this burst in HE.
All measurements above are made with the CsI detectors operating in the 
regular mode with the energy range of about 80-800 keV (deposited energy). 
Only gamma-rays with energy greater than about 200 keV can penetrate 
the spacecraft and leave signals in the CsI detectors installed inside 
of the telescope. 
 
Insight-HXMT is the first Chinese space X-ray telescope, which was 
funded jointly by the China National Space Administration (CNSA) and 
the Chinese Academy of Sciences (CAS). 
More information about it could be found at: 
http://www.hxmt.org.


GRB_name: GRB201228B
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29188
SUBJECT: GRB 201228B: Fermi GBM Final Real-time Localization
DATE:    20/12/28 15:32:09 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 LONG GRB

At 15:21:45 UT on 28 Dec 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 201228B (trigger 630861710.97237 / 201228640).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 8.1, Dec = 50.7 (J2000 degrees, equivalent to J2000 00h 32m, 50d 42'), with a statistical uncertainty of 8.6 degrees.

The angle from the Fermi LAT boresight is 20.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201228640/quicklook/glg_skymap_all_bn201228640.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201228640/quicklook/glg_healpix_all_bn201228640.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201228640/quicklook/glg_lc_medres34_bn201228640.gif


GRB_name: GRB201228B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29189
SUBJECT: Fermi GRB 201228B: Global MASTER-Net observations report 
DATE:    20/12/28 16:45:14 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 201228B ( Fermi GBM team, GCN 29188) errorbox  1104 sec after notice time and 1136 sec after trigger time at 2020-12-28 15:40:42 UT, with upper limit up to  18.8 mag. Observations started at twilight.  The observations began at zenith distance =  4 deg. The sun  altitude  is -15.3 deg. 

The galactic latitude b = -12 deg., longitude l = 120 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1513509

We obtain a following upper limits.  

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

    1227 | 2020-12-28 15:40:42 |      MASTER-Tavrida | (00h 39m 42.51s , +41d 18m 49.9s) |   C |   180 | 18.8 |        
    1227 | 2020-12-28 15:40:42 |      MASTER-Tavrida | (00h 39m 21.36s , +41d 17m 02.5s) |   C |   180 | 18.2 |        
    1426 | 2020-12-28 15:44:02 |      MASTER-Tavrida | (00h 39m 44.66s , +41d 20m 13.1s) |   C |   180 | 18.8 |        
    1566 | 2020-12-28 15:47:21 |      MASTER-Tavrida | (00h 39m 44.39s , +41d 20m 10.4s) |   C |    60 | 18.2 |        
    1566 | 2020-12-28 15:47:21 |      MASTER-Tavrida | (00h 39m 22.94s , +41d 18m 23.7s) |   C |    60 | 18.4 |        
    2262 | 2020-12-28 15:58:58 |      MASTER-Tavrida | (23h 56m 43.97s , +48d 01m 31.2s) |   C |    60 | 17.9 |        
    2262 | 2020-12-28 15:58:58 |      MASTER-Tavrida | (23h 56m 19.28s , +47d 59m 37.6s) |   C |    60 | 17.8 |        
    2342 | 2020-12-28 16:00:17 |      MASTER-Tavrida | (23h 56m 15.68s , +54d 03m 05.9s) |   C |    60 | 17.2 |        
    2342 | 2020-12-28 16:00:17 |      MASTER-Tavrida | (23h 55m 46.62s , +54d 01m 09.4s) |   C |    60 | 17.3 |        
    2500 | 2020-12-28 16:02:56 |      MASTER-Tavrida | (23h 56m 47.04s , +46d 02m 54.9s) |   C |    60 | 17.9 |        
    2501 | 2020-12-28 16:02:56 |      MASTER-Tavrida | (23h 56m 22.59s , +46d 00m 58.5s) |   C |    60 | 17.9 |        
    2759 | 2020-12-28 16:07:14 |      MASTER-Tavrida | (01h 05m 16.31s , +50d 04m 07.5s) |   C |    60 | 18.2 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB201020B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29191
SUBJECT: GRB 201020B: Assy, Koshka, Mondy and Maidanak optical observations
DATE:    20/12/28 21:53:13 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI),  A. Pozanenko (IKI), V. Kim (FAI, Pulkovo Observatory), 
   M. Krugov (FAI), A. Novichonok (Petrozavodsk State University, KIAM), 
A. Zhornichenko (KIAM),  E. Klunko (ISTP),   O. Burhonov (UBAI), Sh. 
Ehgamberdiev (UBAI) report  on behalf of IKI GRB FuN:

We additionally observed the GRB 201020B (Fermi GBM team, GCN 28702; 
Malacaria et al., GCN 28710; Arimoto et al., GCN 28716; Ursi et al., GCN 
28714; Ridnaia et al., GCN 28723) with AZT-20 telescope of Assy 
observatory, Zeiss-1000 of Koshka observatory, AZT-33IK telescope of 
Sayan observatory (Mondy), and AZT-22 telescope of Maidanak observatory. 
The optical afterglow (Lipunov et al., GCN 28718; Xu et al., GCN 28719; 
Belkin et al., GCN 28725; Breeveld & Lien, GCN 28743; Vinko et al., GCN 
28750; Kumar et al., GCN 28753; Belkin et al., GCN 28768; Vinko et al., 
GCN 28769; Vinko et al., GCN 28769; Panchal et al., GCN 28772; Nicastro 
  et al., GCN 28773; Kumar  et al., GCN 28776; Kumar  et al., GCN 28781) 
with redshift of z= 0.804 (Kann  et al., GCN 28765) is  detected in most 
of stacked images of our observations in R-filter.

Preliminary light curve of the afterglow based on our observations 
including reported earlier (Belkin et al., GCNs 28725, 28768) can be 
found in

http://grb.rssi.ru/GRB201020B/GRB201020B_R_LC.png

The photometry is based on the nearby USNO-B1.0 stars
USNO-B1.0_id R2
1670-0037414 16.74
1670-0037586 16.16


GRB_name: GRB201229A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29192
SUBJECT: GRB 201229A: Swift detection of a burst with a possible optical counterpart
DATE:    20/12/29 11:23:17 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

B. Sbarufatti (PSU), S. D. Barthelmy (GSFC), J.D. Gropp (PSU) and
A. Y. Lien (GSFC/UMBC) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 10:59:30 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 201229A (trigger=1015088).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 210.708, +48.197 which is 
   RA(J2000) = 14h 02m 50s
   Dec(J2000) = +48d 11' 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 about 7 sec.  The peak count rate
was ~500 counts/sec (15-350 keV), at ~2 sec after the trigger. 

The XRT began observing the field at 11:01:22.2 UT, 111.4 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source with an enhanced position: RA, Dec 210.6891,
48.1976 which is equivalent to:
   RA(J2000)  = 14h 02m 45.39s
   Dec(J2000) = +48d 11' 51.2"
with an uncertainty of 2.2 arcseconds (radius, 90% containment). This
location is 45 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 1.78
x 10^20 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 116 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  = 14:02:45.41 = 210.68921
  DEC(J2000) = +48:11:53.8  =  48.19828
with a 90%-confidence error radius of about 0.62 arc sec. This position is 3.1
arc sec. from the center of the XRT error circle. The estimated magnitude is
18.19 with a 1-sigma error of about  0.14. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.01. 

Burst Advocate for this burst is B. Sbarufatti (bxs60 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: GRB201229A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29193
SUBJECT: GRB 201229A: Enhanced Swift-XRT position
DATE:    20/12/29 14:53:01 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 1463 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 201229A, 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 = 210.68844, +48.19775 which is equivalent
to:

RA (J2000): 14h 02m 45.23s
Dec (J2000): +48d 11' 51.9"

with an uncertainty of 1.7 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: GRB201229B
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29194
SUBJECT: GRB 201229B: Fermi GBM Final Real-time Localization
DATE:    20/12/29 15:30:31 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 15:20:12 UT on 29 Dec 2020, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 201229B (trigger 630948017.705592 / 201229639).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 340.4, Dec = -52.0 (J2000 degrees, equivalent to J2000 22h 41m, -52d 00'), with a statistical uncertainty of 1.3 degrees.

The angle from the Fermi LAT boresight is 19.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201229639/quicklook/glg_skymap_all_bn201229639.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201229639/quicklook/glg_healpix_all_bn201229639.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2020/bn201229639/quicklook/glg_lc_medres34_bn201229639.gif


GRB_name: GRB201229B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29195
SUBJECT: GRB 201229B: BALROG localization (Fermi Trigger 630948017 / GRB 201229639)
DATE:    20/12/29 15:48:58 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
630948017 at 15:20:12 on 29 Dec. 2020 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) = 341.8+/-2.3 deg
Decl.(2000.0) = -52.8+/-1.3 deg
We estimate an additional systematic error of 2 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB201229639/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB201229639/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB201229639/json

                        


GRB_name: GRB201227A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29196
SUBJECT: Konus-Wind observation of GRB 201227A
DATE:    20/12/29 16:42:04 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

D. Svinkin, S. Golenetskii, R. Aptekar, D. Frederiks,
M. Ulanov, A. Tsvetkova, A. Lysenko, A. Ridnaia, and T. Cline
on behalf of the Konus-Wind team, report:

The short-duration, very bright GRB 201227A
(AGILE detection: Ursi et al., GCN Circ. 29179;
IPN triangulation: Svinkin et al., GCN Circ. 29182;
Insight-HXMT/HE detection: Xiao et al., GCN Circ. 29187)
triggered Konus-Wind at T0=54846.705 s UT (15:14:06.705).

The burst light curve shows a multipeaked structure
which starts at ~T0-28 ms and has a total duration of ~106 ms.
The emission is seen up to ~4 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB201227_T54846/

As observed by Konus-Wind, the burst
had a fluence of 4.30(-0.52,+0.54)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0,
of 1.05(-0.18,+0.18)x10^-4 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+0.064 s)
is best fit in the 20 keV - 4 MeV range
by a power law with exponential cutoff model:
dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.17(-0.18,+0.21)
and Ep = 870(-130,+151) keV (chi2 = 17/19 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -2.3
(chi2 = 17/18 dof).

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB201229B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29197
SUBJECT: Fermi GRB 201229B: Global MASTER-Net observations report 
DATE:    20/12/29 20:00:17 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 201229B ( Fermi GBM team, GCN 29194) errorbox  15696 sec after notice time and 15741 sec after trigger time at 2020-12-29 19:42:34 UT, with upper limit up to  17.8 mag. The observations began at zenith distance = 59 deg. The sun  altitude  is -20.2 deg. 

The galactic latitude b = -56 deg., longitude l = 338 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1514878

We obtain a following upper limits.  

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

   15772 | 2020-12-29 19:42:34 |         MASTER-SAAO | (22h 22m 49.08s , -52d 05m 54.8s) |   C |    60 | 17.6 |        
   15932 | 2020-12-29 19:45:14 |         MASTER-SAAO | (22h 32m 27.56s , -54d 04m 14.0s) |   C |    60 | 17.8 |        
   16096 | 2020-12-29 19:47:58 |         MASTER-SAAO | (22h 40m 43.06s , -50d 04m 29.3s) |   C |    60 | 17.4 |        
   16176 | 2020-12-29 19:49:18 |         MASTER-SAAO | (22h 48m 53.55s , -52d 05m 05.3s) |   C |    60 | 17.8 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB201104B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29198
SUBJECT: GRB 201104B: Maidanak and CrAO optical observations
DATE:    20/12/29 22:49:38 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI), A. Pozanenko (IKI), V. Rumyantsev (CrAO),  O. Burhonov 
(UBAI), Sh. Ehgamberdiev (UBAI) report  on behalf of IKI GRB FuN:

We observed GRB 201104B (Sbarufatti et al., GCN 28825) with AZT-22 
telescope of Maidanak Observatory  and ZTSh telescope of CrAO.
The optical afterglow (Marshall et al., GCN 28827; Vielfaure  et al., 
GCN 28840; Oates  et al., GCN 28851; Belkin et al., GCNs 28852, 28856, 
28871; Gupta et al., GCN 28860; Hosokawa et al., GCN 28870) at redshift 
z = 1.954 (Vielfaure et al., GCN 28840) is detected in stacked images. 
Preliminary photometry of the afterglow is following.

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

2020-11-09 15:57:43  4.95413 R 12*300 22.89 0.09 24.3 AZT-22
2020-11-13 19:50:05  9.12784 R 45*120 23.20 0.12 24.0 ZTSh

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

A light curve base on our observations including reported earlier 
(Belkin et al., GCNs 28852, 28856, 28871) can be found in

http://grb.rssi.ru/GRB201104B/GRB201104B_LC_R.png


GRB_name: GRB201229A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29199
SUBJECT: GRB 201229A: Swift-BAT refined analysis
DATE:    20/12/29 23:12:48 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

A. Y. Lien (GSFC/UMBC), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), B. Sbarufatti (PSU)
M. Stamatikos (OSU), T. N. Ukwatta (LANL)
(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 201229A (trigger #1015088)
(Sbarufatti et al., GCN Circ. 29192).  The BAT ground-calculated position is
RA, Dec = 210.692, 48.209 deg which is
   RA(J2000)  =  14h 02m 46.1s
   Dec(J2000) = +48d 12' 33.0"
with an uncertainty of 2.6 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 26%.

The mask-weighted light curve shows a multi-peaked structure that
starts at ~T-45 s and ends at ~T+15 s. There is a weak pulse occurring
at ~T-40 s, followed by the main peak at ~T0. T90 (15-350 keV)
is 53.3 +- 4.6 sec (estimated error including systematics).

The time-averaged spectrum from T-44.43 to T+13.62 sec is best fit
by a simple power-law model.  The power law index of the time-averaged
spectrum is 1.40 +- 0.29.  The fluence in the 15-150 keV band is
1.3 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from
T+0.41 sec in the 15-150 keV band is 1.7 +- 0.4 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/1015088/BA/


GRB_name: GRB201229A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29200
SUBJECT: GRB 201229A: Swift-XRT refined Analysis
DATE:    20/12/30 00:06:20 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

A. D'Ai (INAF-IASFPA), D.N. Burrows (PSU), J. D. Gropp (PSU), A.P.
Beardmore (U. Leicester), P.A. Evans (U. Leicester), J.P. Osborne (U.
Leicester), A. Melandri (INAF-OAB), T. Sbarrato (INAF-OAB) and B.
Sbarufatti report on behalf of the Swift-XRT team:

We have analysed 8.6 ks of XRT data for GRB 201229A (Sbarufatti et al.
GCN Circ. 29192), from 114 s to 34.8 ks after the  BAT trigger. The
data comprise 22 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. 29193).

The light curve can be modelled with an initial power-law decay with an
index of alpha=2.2 (+0.5, -0.3), followed by a break at T+262 s to an
alpha of 0.49 (+/-0.03).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.80 (+/-0.12). The
best-fitting absorption column is  1.3 (+/-0.4) x 10^21 cm^-2, in
excess of the Galactic value of 1.8 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 3.8 x 10^-11 (3.9 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.3 (+/-0.4) x 10^21 cm^-2
Galactic foreground: 1.8 x 10^20 cm^-2
Excess significance: 5.2 sigma
Photon index:      1.80 (+/-0.12)

If the light curve continues to decay with a power-law decay index of
0.49, the count rate at T+24 hours will be 0.048 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.8 x
10^-12 (1.9 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01015088.

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


GRB_name: GRB201223A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29201
SUBJECT: GRB 201223A: SVOM-GWAC detected the optical counterpart during prompt emission phase
DATE:    20/12/30 00:50:53 GMT
FROM:    Liping Xin at NAOC, SVOM  <xlp@nao.cas.cn>

L. P. Xin(NAOC),  X. H. Han(NAOC), J. Y. Wei(NAOC),  L. H. Li(NAOC), 
J. Wang(GXU), D. Turpin(CEA),  H. B. Cai(NAOC), X. Y. Wang(NJU),   
C. Wu(NAOC),  X. G. Wang(GXU),  Z. G. Dai (NJU), G. W. Li(NAOC),  
E. W. Liang (GXU),  S.S.Sun(GXU), L. Huang(NAOC), X. M. Lu(NAOC),  
Y. G. Yang(HNU), C. Gao(GXU), Y. L. Qiu(NAOC), and J. S. Deng(NAOC) report: 


The optical counterpart of GRB 201223A (Gropp et al., GCN #29158, 
Wood et al., GCN #29161) reported by (Lipunov et al., GCN #29157; 
Gropp et al., GCN #29158; Zhu et al., GCN #29159; Hu et al., GCN #29160;
Hosokawa et al., GCN #29164; Filipp Dmitrievich Romanov GCN #29165;
Xin et al., GCN #29166; Belkin et al., GCN #29167;  Kumar et al., GCN #29168; 
Xu et al., GCN #29169; Gupta te al., GCN #29173; Pankov et al., GCN #29174;
Kumar et al., GCN #29176; Belles et al., GCN #29177 )
was detected  by Ground Wide Angle Camera (GWAC) in white band 
at Xinglong observatory, China, during the Swift prompt emission phase. 
The exposure time for each GWAC image is 10 seconds. 

Preliminary process showed that the brightness was about R~15.5 mag at ~2 sec after the burst, 
and then brighten to the peak of R~14.8 mag at about 80 sec  post the trigger time.

All these magnitudes were calibrated to USNO B1.0 R2 mag catalog. 

More analyses are still continuing.


GRB_name: GRB201227A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29202
SUBJECT: GRB 201227A: Swift-XRT observations
DATE:    20/12/30 00:59:11 GMT
FROM:    Aaron Tohuvavohu at U Toronto  <aaron.tohu@gmail.com>

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), A. Melandri (INAF-OAB) and
P.A. Evans (U. Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the IPN-detected
burst GRB 201227A (Ursi et al. GCN Circ. 29179) in a series of
observations tiled on the sky. The total exposure time is 7.5 ks,
distributed over 4 tiles; the maximum exposure at a single sky location
was 5.3 ks. The data were collected between T0+51.6 ks and T0+80.7 ks,
and are entirely in Photon Counting (PC) mode. 

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 1:
  RA (J2000):  170.6083  =  11:22:25.99
  Dec (J2000): -73.4880  =  -73:29:16.9
  Error: 7.4 arcsec (radius, 90% conf.)
  Count-rate: (4.4 [+1.7, -1.4])e-3 ct s^-1   
  Distance: 670 arcsec from IPN position.
  Flux: (9.0 [+3.5, -2.8])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 2:
  RA (J2000):  170.6190  =  11:22:28.57
  Dec (J2000): -73.4798  =  -73:28:47.2
  Error: 4.8 arcsec (radius, 90% conf.)
  Count-rate: (3.6 [+1.6, -1.3])e-3 ct s^-1   
  Distance: 698 arcsec from IPN position.
  Flux: (1.34 [+0.60, -0.47])e-13 erg cm^-2 s^-1 (observed, 0.3-10 keV)

Source 3:
  RA (J2000):  169.8508  =  11:19:24.19
  Dec (J2000): -73.5866  =  -73:35:11.9
  Error: 5.6 arcsec (radius, 90% conf.)
  Count-rate: (2.8 [+1.4, -1.1])e-3 ct s^-1   
  Distance: 290 arcsec from IPN position.

Source 4:
  RA (J2000):  171.2953  =  11:25:10.87
  Dec (J2000): -73.6326  =  -73:37:57.4
  Error: 4.4 arcsec (radius, 90% conf.)
  Count-rate: (4.2 [+2.6, -1.9])e-3 ct s^-1   
  Distance: 1194 arcsec from IPN position.

The results of the XRT-team automatic analysis of the tiled XRT
observations, including a position-specific upper limit calculator, are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00096.

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


GRB_name: GRB201229A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29203
SUBJECT: GRB 201229A: Nanshan/NEXT optical upper limit
DATE:    20/12/30 03:53:43 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

S.Y. Fu (NAOC), Z.P. Zhu (HUST,NAOC), X. Liu, D. Xu (NAOC), X. Gao 
(Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:

We observed the field of GRB 201229A (Sbarufatti et al., GCN 29192) 
using the NEXT-0.6m telescope located at Nanshan, Xinjiang, China. We 
obtained 5 x 200 s frames in the Sloan r-band, starting at 19:52:23 UT 
on 2020-12-29, i.e., 8.88 hr after the burst.

No optical source is detected in our stacked image at the Swift/UVOT 
position (Sbarufatti et al., GCN 29192), down to a upper limiting of 
r~20.4, calibrated with the nearby PanSTARRS field.


GRB_name: GRB201229A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29204
SUBJECT: GRB 201229A: SAO RAS optical observations
DATE:    20/12/30 10:47:31 GMT
FROM:    Moskvitin Alexander at SAO RAS  <mosk@sao.ru>

A. S. Moskvitin, O. I. Spiridonova (SAO RAS)
on behalf of GRB follow-up team report.

We observed the field of the GRB 201229A (B. Sbarufatti et al.,
GCN #29192) with the SAO RAS 1m telescope Zeiss-1000 equipped
with CCD photometer on December 30, 00:43:31 -- 01:40:03 UT
(T_mid - T0 = 0.59186 days).

The possible OT reported by Swift team is clearly detected
in the stacked 6 x 300 sec. Rc band image with the coordinates
R.A. = 14:02:45.38, Dec. = +48:11:53.5 +/- 0".1 (J2000).
Preliminary photometry of the object is R = 21.29 +/- 0.1
(based on R2 magnitudes of nearby USNO-B1 stars).
Using UVOT and NEXT-0.6m results (S.Y. Fu et al., GCN# 29203)
we confirm the GRB OT.


GRB_name: GRB201229A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29205
SUBJECT: GRB 201229A: AbAO optical afterglow detection, TSHAO optical upper limit
DATE:    20/12/30 11:31:43 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We observed the field of  GRB 201229A (Sbarufatti et al., GCN 29192) 
with AS-32 telescope of Abastumani observatory (AbAO), and Zeiss-1000 
telescope of TSHAO in R-filter. We detected the optical object at the 
edge of enhanced XRT position (Osborne et al., GCN 29193). An optical 
afterglow candidate  (Sbarufatti et al., GCN 29192; Moskvitin at al., 
GCN 29204) is detected in AbAO observations and not detected in   TSHAO 
observations with shallow upper limit. Coordinates of the optical object 
  (J2000) 14:02:45.36 +48:11:53.5 with uncertainty of 0.3 arcsec (in 
both coordinates) are  consistent with coordinates reported by UVOT 
(Sbarufatti et al., GCN 29192) and SAO RAS  (Moskvitin at al., GCN 
29204). Preliminary photometry of the object is following

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

2020-12-29  20:38:18   0.42095  R    23*120  n/d   n/d  20.2  Zeiss-1000
2020-12-30  01:52:12   0.64354  R    68*60   21.1  0.2  21.3  AS-32


The photometry is based on SDSS DR12 star (Lupton transformations)

RA         DEC       R(Lupton)
210.720000 48.157954 18.28

The non-detection of the object by Zeiss-1000 is consistent with 
Nanshan/NEXT optical upper limit (Fu et al., GCN 29203).

The object is absent in SDSS DR12 and we confirm the afterglow of GRB 
201229A.


GRB_name: GRB201227A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29206
SUBJECT: GRB 201227A: Fermi GBM observation
DATE:    20/12/30 14:00:33 GMT
FROM:    Rachel Dunwoody at UCD  <rachel.dunwoody@ucdconnect.ie>

S. Lesage, P. Veres, C. Meegan (all UAH), J. Mangan (UCD) and R. Dunwoody
(UCD)
report on behalf of the Fermi GBM Team:

"At 15:14:07.41 UT on 23 December 2020, the Fermi Gamma-Ray Burst Monitor
(GBM)
triggered and located GRB 201227A (trigger 630774852 / 201227635),
which was also detected by Konus-Wind (Svinkin et al. GCN 29196),
Insight-HXMT (Xiao et al., GCN 29187),
AGILE (Ursi et al., GCN 29179) and IPN (Svinkin et al., GCN 29182).
The GBM on-ground location is consistent with the IPN position.



The angle from the Fermi LAT boresight at the GBM trigger time is 135
degrees.



The GBM light curve consists of a short bright pulse
with a duration (T90) of about 0.1 s (50-300 keV).
The time-averaged spectrum from T0-64 ms to T0+128 ms is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.47 +/- 0.07 and
the cutoff energy, parameterized as Epeak, is 1076 +/- 96 keV.

The event fluence (10-1000 keV) in this time interval is
(3.6 +/- 0.1)E-6 erg/cm^2. The 64-ms peak photon flux measured
starting from T0 in the 10-1000 keV band
is 100 +/- 5 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: GRB201227A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29208
SUBJECT: GRB 201227A: Chilescope optical observations, possible optical counterpart
DATE:    20/12/30 21:14:02 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI), A. Pozanenko (IKI), M. Krugov (FAI), P. Minaev (IKI) 
report on behalf of GRB IKI FuN collaboration:

We observed the field of XRT 1-3 sources (D'Elia et al., GCN 29202)
(hereafter X1,X2,X3) found in IPN localization area (Svinkin et al.,
GCN 29182) of GRB 201227A (Ursi et al., GCN 29179; Xiao et al., GCN
29187; Svinkin et al., GCN 29196; Lesage et al., GCN 29206) with
Chilescope RC-1000 starting on 2020-12-29 (UT) 04:02:05 in r'-filter.

The X3 source was observed by one 300 s exposure, and the filed of X1,X2
was observed by 3*300 s exposure. The limiting magnitude of single
exposure of X3 and the stacked 3*300 s exposure is about r'=20.9.

There are two optical sources close or on the edge of the XRT error 
circle localization of X3. Both sources are present in USNO-B1.0 and our 
photometry of the sources show no excess in brightness in comparison
with any R-mag of USNO-B1.0.

Also there are two optical sources close or on the edge of the XRT error
circle localization of X1. Both source are also present in USNO-B1.0 and
our photometry of the sources show no excess in brightness in comparison
with any R-mag of USNO-B1.0.

At the edges of X2 error circle we found two sources which not presented
in USNO-B1.0. The coordinates of the first one (X2_O1) is RA(J2000)=11h 
22m 29.34s, Dec(J2000)=-73d 28â€™ 44.9â€™â€™. The photometry of the source is 
r'= 20.50 +/-0.29 and the source is barely visible in DSS2 plate. The 
coordinates of second one (X2_02) is RA(J2000)=11h 22m 27.94s, 
Dec(J2000)=-73d 28â€™ 50.6â€™â€™. The photometry of the source is r'= 20.52 
+/-0.29 and the source is not presented in DSS2 plate. We may suggest 
the optical object X2_02 could be a counterpart of GRB 201227A.

The photometry is based on nearby stars from the APASS_DR8 and still
preliminary

RA DEC r
11:19:31.40904 -73:35:47.6880 14.090
11:19:44.89128 -73:34:49.6092 15.180
11:19:36.65304 -73:36:30.2112 15.307

Taking into account that early more deep observations of the IPN field 
by GRAWITA VST-ESO PARANAL (Izzo et al., GCN 29207) does no show any 
counterpart we  may suggest the X2_O2 source (RA(J2000)=11h 22m 27.936s, 
Dec(J2000)=-73d 28â€™ 50.55â€™â€™) is a possible optical counterpart or 
kilonova of GRB 201227A.


GRB_name: GRB201216C
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29210
SUBJECT: GRB 201216C: TSHAO, Terskol, Mondy optical upper limits
DATE:    20/12/31 17:43:53 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI), A. Pozanenko (IKI),  M. Krugov (FAI), P. Levkina 
(INASAN), E. Klunko (ISTP), N. Pankov (IKI, HSE)   report on behalf of 
GRB IKI FuN:

We observed   GRB 201216C (Beardmore et al., GCN  29061)  with 
Zeiss-1000 (West) telescope of TSHAO, Zeiss-2000 telescope of Terskol 
observatory, and AZT-33IK telescope of Mondy observatory.  The optical 
afterglow (Izzo et al., GCN  29066; Jelinek  et al., GCN 29070; Oates et 
al., GCN 29071; Shrestha et al., GCN  29085) at possible redshift of z = 
1.1  of presumably optically dark GRB (Vielfaure et al., GCN 29077) is 
not detected in our observations. Preliminary photometry of the field is 
following.

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

2020-12-17 14:20:49  0.6968    R  60*180   n/d  n/d  19.8 Zeiss-1000(W)
2020-12-18 16:47:27  1.7653    R  28*180   n/d  n/d  21.9 Zeiss-2000
2020-12-19 12:00:27  2.5681    R  45*120   n/d  n/d  22.1 AZT-22

Photometry is based on USNO-B1.0 stars
USNO-B1.0_id R2
1065-0011134 15.33
1065-0011173 15.44
1064-0011283 16.67


GRB_name: GRB201229A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29213
SUBJECT: GRB 201229A: Swift/UVOT Detection
DATE:    21/01/01 02:06:07 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <mhs18@psu.edu>

M. H. Siegel (PSU) and B. Sbarufatti (PSU)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 201229A
117 s after the BAT trigger (Sbarufatti et al., GCN Circ. 29192).
A source consistent with the XRT position
(Osborne et al. GCN Circ. 29193) is detected in the initial UVOT exposures, consistent
with the optical transient reported in the initial circular and confirmed by
SAO (Moskvitin et al., GCN Circ. 29203) and AbAO (Pankov et al., GCN Circ. 29205).

The preliminary UVOT position is:
    RA  (J2000) =  14:02:45.40 = 210.68916 (deg.)
    Dec (J2000) = +48:11:53.3  =  48.19814 (deg.)
with an estimated uncertainty of 0.44 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)         117          266          147      18.22 +/- 0.05
white              555          749           38      18.50+/-0.13
white              879         1029          147      19.17+/-0.13
white             1182         1548           58      19.42+/-0.34
white            23280        24102          801      20.88+/-0.22
v                  605         1597          116     >18.48
v                17146        34853         1217     >20.39
b                  531         1523           97     >19.33
b                22367        23274          885     >21.24
u (fc)             275          525          245      18.13+/-0.09
u                  680         5086          107      18.57+/-0.25
u                12362        29756         1220      20.54+/-0.34
uvw1               654         5071          254      19.04+/-0.25
uvw1             28021        28921          885     >20.45
uvw2             16239        34408         1771      20.27+/-0.21

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.01 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB210101A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29215
SUBJECT: GRB 210101A: Fermi GBM Final Real-time Localization
DATE:    21/01/01 15:03:31 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 14:53:06 UT on 1 Jan 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210101A (trigger 631205591.859738 / 210101620).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 136.7, Dec = 50.1 (J2000 degrees, equivalent to J2000 09h 06m, 50d 06'), with a statistical uncertainty of 4.6 degrees.

The angle from the Fermi LAT boresight is 147.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210101620/quicklook/glg_skymap_all_bn210101620.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/bn210101620/quicklook/glg_healpix_all_bn210101620.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210101620/quicklook/glg_lc_medres34_bn210101620.gif


GRB_name: GRB210101A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29216
SUBJECT: GRB 210101A: BALROG localization (Fermi Trigger 631205591 / GRB 210101620)
DATE:    21/01/01 17:05:32 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
631205591 at 14:53:06 on 01 Jan. 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) = 149.6+/-3.8 deg
Decl.(2000.0) = 53.1+/-2.4 deg
We estimate an additional systematic error of 1 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB210101620/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB210101620/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB210101620/json

                        


GRB_name: GRB210101A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29222
SUBJECT: Fermi GRB 210101A: Global MASTER-Net observations report 
DATE:    21/01/02 04:00:09 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 210101A ( Fermi GBM team, GCN 29215) errorbox  19545 sec after notice time and 19603 sec after trigger time at 2021-01-01 20:19:50 UT, with upper limit up to  18.2 mag. The observations began at zenith distance = 35 deg. The sun  altitude  is -62.4 deg. 

MASTER-IAC robotic telescope  located in Spain (IAC Teide Observatory) started inspect of the Fermi GRB 210101A errorbox  38568 sec after notice time and 38626 sec after trigger time at 2021-01-02 01:36:52 UT, with upper limit up to  18.2 mag. The observations began at zenith distance = 36 deg. The sun  altitude  is -81.5 deg. 

The galactic latitude b = 42 deg., longitude l = 169 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1516794

We obtain a following upper limits.  

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

   19633 | 2021-01-01 20:19:50 |      MASTER-Tavrida | (08h 53m 10.40s , +56d 17m 44.1s) |   C |    60 | 18.0 |        
   19633 | 2021-01-01 20:19:50 |      MASTER-Tavrida | (09h 03m 54.67s , +56d 15m 14.2s) |   C |    60 | 18.2 |        
   20536 | 2021-01-01 20:34:53 |      MASTER-Tavrida | (08h 53m 01.80s , +56d 17m 48.0s) |   C |    60 | 18.2 |        
   20536 | 2021-01-01 20:34:53 |      MASTER-Tavrida | (09h 03m 45.63s , +56d 15m 32.5s) |   C |    60 | 18.1 |        
   38656 | 2021-01-02 01:36:52 |          MASTER-IAC | (09h 23m 12.29s , +56d 10m 19.9s) |   C |    60 | 18.2 |        
   43403 | 2021-01-02 02:56:00 |      MASTER-Tavrida | (08h 44m 09.21s , +53d 57m 34.6s) |   C |    60 | 18.0 |        
   43403 | 2021-01-02 02:56:00 |      MASTER-Tavrida | (08h 33m 51.91s , +54d 00m 03.2s) |   C |    60 | 17.7 |        
   44349 | 2021-01-02 03:11:45 |      MASTER-Tavrida | (08h 44m 05.63s , +53d 56m 08.2s) |   C |    60 | 18.0 |        
   44349 | 2021-01-02 03:11:45 |      MASTER-Tavrida | (08h 33m 52.43s , +53d 58m 37.8s) |   C |    60 | 18.0 |        
   45423 | 2021-01-02 03:29:40 |      MASTER-Tavrida | (08h 44m 05.11s , +53d 57m 15.1s) |   C |    60 | 18.0 |        
   45423 | 2021-01-02 03:29:40 |      MASTER-Tavrida | (08h 33m 50.61s , +54d 00m 16.0s) |   C |    60 | 18.0 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB210102B
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29223
SUBJECT: GRB 210102B: MAXI/GSC detection
DATE:    21/01/02 12:38:16 GMT
FROM:    Motoko Serino at RIKEN/MAXI  <motoko@crab.riken.jp>

C. Guo (RIKEN), M. Serino (AGU), H. Negoro, 
M. Nakajima, M. Aoki, K. Kobayashi, R. Takagi, K, Asakura, K, Seino (Nihon U.),
T. Mihara, T. Tamagawa, M. Matsuoka (RIKEN),
T. Sakamoto, S. Sugita, H. Nishida, K. Komachi, A. Yoshida (AGU),
Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, Y. Okamoto, S. Kitakoga (Chuo U.),
M. Shidatsu (Ehime U.),
N. Kawai, R. Adachi, M. Niwano, R. Hosokawa (Tokyo Tech),
S. Nakahira, Y. Sugawara, S. Ueno, H. Tomida, M. Ishikawa, M. Tominaga, T. Nagatsuka (JAXA),
Y. Ueda, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake, U. Goto, R. Uematsu (Kyoto U.),
H. Tsunemi (Osaka U.),
M. Yamauchi, K. Kurogi, K. Miike (Miyazaki U.),
T. Kawamuro (NAOJ),
K. Yamaoka (Nagoya U.),
Y. Kawakubo (LSU),
M. Sugizaki (NAOC) 
report on behalf of the MAXI team:

The MAXI/GSC nova alert system triggered on a bright uncatalogued X-ray transient source at 2021-01-02T09:03:48 UT.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (353.323 deg, -21.086 deg) = (23 33 18, -21 05 10) (J2000)
with a statistical 90% C.L. circular error region
with a radius of 0.5 deg.
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 238 +- 31 mCrab
(2.0-4.0keV, 1 sigma error).
There was no significant excess flux in the next transit at 10:36 UT
with an upper limit of 20 mCrab.


GRB_name: GRB210102B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29224
SUBJECT: GRB 210102B: Tiled Swift observations
DATE:    21/01/02 14:40:06 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 series of observations, tiled on the sky, of the
MAXI GRB 210102B. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00097

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the MAXI event is high: 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: GRB210102C
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29226
SUBJECT: GRB 210102C: Swift detection of a burst
DATE:    21/01/02 20:47:29 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

E. Troja (NASA/GSFC/UMCP), M. G. Bernardini (INAF-OAB),
C. Gronwall (PSU), A. Y. Lien (GSFC/UMBC), A. Melandri (INAF-OAB),
D. M. Palmer (LANL) and T. Sbarrato (INAF-OAB) report on behalf of the
Neil Gehrels Swift Observatory Team:

At 20:38:11 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210102C (trigger=1015728).  Swift did not slew due to 
an observing constraint. 
The BAT on-board calculated location is 
RA, Dec 235.737, -37.222 which is 
   RA(J2000) = 15h 42m 57s
   Dec(J2000) = -37d 13' 19"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a double-peaked
structure with a duration of about 100 sec.  The peak count rate
was ~3000 counts/sec (15-350 keV), at ~65 sec after the trigger. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 15:14 UT on 2021 January 06. There will thus be no XRT
or UVOT data for this trigger before this time. 

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: GRB210102C
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29227
SUBJECT: Swift GRB 210102C: Global MASTER-Net observations report 
DATE:    21/01/03 00:56:12 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 210102C ( E. Troja et al., GCN 29226) errorbox  14718 sec after notice time and 14840 sec after trigger time at 2021-01-03 00:45:31 UT, with upper limit up to  17.5 mag. The observations began at zenith distance = 78 deg. The sun  altitude  is -27.8 deg. 

The galactic latitude b = 14 deg., longitude l = 337 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1517509

We obtain a following upper limits.  

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

   14931 |         MASTER-SAAO |   C |   180 | 17.5 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB210102C
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29228
SUBJECT: GRB 210102C: Fermi GBM detection
DATE:    21/01/03 06:07:38 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 20:39:14.40 UT on 2 January 2021, the Fermi Gamma-Ray Burst Monitor
(GBM)
triggered and located GRB 210102C (trigger 631312759 / 210102861),
which was also detected by the Swift/BAT (Troja et al. 2021, GCN 29226);
GBM triggered on a later, brighter emission.
The GBM on-ground location is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 131
degrees.

The GBM light curve consists of multiple peaks followed by some
extended emission with a duration (T90) of about 84 s (50-300 keV).
The time-averaged spectrum from T0-3.07 s to T0+9.22 s (bright emission
which triggered GBM)
is best fit by a power law function with an exponential
high-energy cutoff. The power law index is -1.41 +/- 0.08 and
the cutoff energy, parameterized as Epeak, is 209 +/- 39 keV.

The event fluence (10-1000 keV) in this time interval is
(5.219 +/- 0.332)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+4.99 s in the 10-1000 keV band
is 7.9 +/- 0.4 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: GRB210102C
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29229
SUBJECT: Fermi GRB 210102C: Global MASTER-Net observations report 
DATE:    21/01/03 08:45:09 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 210102C ( S. Poolakkil et al., GCN 29228) errorbox  14713 sec after notice time and 14777 sec after trigger time at 2021-01-03 00:45:31 UT, with upper limit up to  17.7 mag. The observations began at zenith distance = 78 deg. The sun  altitude  is -27.8 deg. 

MASTER-OAFA robotic telescope  located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 210102C errorbox  37485 sec after notice time and 37549 sec after trigger time at 2021-01-03 07:05:03 UT, with upper limit up to  17.4 mag. The observations began at zenith distance = 75 deg. The sun  altitude  is -25.8 deg. 

The galactic latitude b = 14 deg., longitude l = 341 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1517531

We obtain a following upper limits.  

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

   14868 | 2021-01-03 00:45:31 |         MASTER-SAAO | (15h 37m 40.48s , -37d 10m 22.5s) |   C |   180 | 17.5 |        
   15229 | 2021-01-03 00:51:33 |         MASTER-SAAO | (15h 37m 40.65s , -37d 11m 17.2s) |   C |   180 | 17.7 |        
   15508 | 2021-01-03 00:56:12 |         MASTER-SAAO | (15h 37m 43.87s , -37d 11m 02.4s) |   C |   180 | 17.7 |        
   37639 | 2021-01-03 07:05:03 |         MASTER-OAFA | (15h 41m 31.97s , -37d 50m 25.5s) |   C |   180 | 16.9 |        
   38059 | 2021-01-03 07:12:02 |         MASTER-OAFA | (15h 41m 30.60s , -37d 52m 29.2s) |   C |   180 | 17.2 |        
   38563 | 2021-01-03 07:20:27 |         MASTER-OAFA | (15h 41m 33.22s , -37d 52m 25.5s) |   C |   180 | 17.2 |        
   38932 | 2021-01-03 07:27:35 |         MASTER-OAFA | (15h 58m 44.82s , -34d 37m 34.2s) |   C |    60 | 16.9 |        
   39011 | 2021-01-03 07:28:55 |         MASTER-OAFA | (15h 39m 27.24s , -34d 39m 06.6s) |   C |    60 | 17.3 |        
   39091 | 2021-01-03 07:30:14 |         MASTER-OAFA | (15h 56m 09.32s , -32d 37m 35.3s) |   C |    60 | 16.9 |        
   39170 | 2021-01-03 07:31:34 |         MASTER-OAFA | (15h 43m 02.44s , -36d 37m 27.2s) |   C |    60 | 17.2 |        
   39249 | 2021-01-03 07:32:53 |         MASTER-OAFA | (15h 37m 14.21s , -32d 36m 54.4s) |   C |    60 | 17.2 |        
   39329 | 2021-01-03 07:34:12 |         MASTER-OAFA | (16h 02m 42.12s , -36d 39m 25.7s) |   C |    60 | 17.0 |        
   39408 | 2021-01-03 07:35:32 |         MASTER-OAFA | (15h 47m 50.85s , -38d 37m 22.4s) |   C |    60 | 16.9 |        
   39488 | 2021-01-03 07:36:52 |         MASTER-OAFA | (15h 54m 49.80s , -30d 37m 41.3s) |   C |    60 | 16.9 |        
   39886 | 2021-01-03 07:43:30 |         MASTER-OAFA | (15h 58m 45.09s , -34d 38m 17.8s) |   C |    60 | 17.0 |        
   39966 | 2021-01-03 07:44:49 |         MASTER-OAFA | (16h 08m 24.29s , -34d 37m 29.7s) |   C |    60 | 16.8 |        
   40045 | 2021-01-03 07:46:09 |         MASTER-OAFA | (15h 39m 33.51s , -34d 37m 53.1s) |   C |    60 | 17.3 |        
   40124 | 2021-01-03 07:47:28 |         MASTER-OAFA | (15h 49m 07.52s , -34d 39m 05.9s) |   C |    60 | 17.1 |        
   40205 | 2021-01-03 07:48:49 |         MASTER-OAFA | (15h 56m 13.18s , -32d 38m 48.1s) |   C |    60 | 17.1 |        
   40285 | 2021-01-03 07:50:09 |         MASTER-OAFA | (16h 05m 35.69s , -32d 37m 31.1s) |   C |    60 | 16.8 |        
   40365 | 2021-01-03 07:51:29 |         MASTER-OAFA | (15h 42m 59.86s , -36d 38m 48.3s) |   C |    60 | 17.2 |        
   40444 | 2021-01-03 07:52:48 |         MASTER-OAFA | (15h 52m 56.54s , -36d 37m 37.3s) |   C |    60 | 17.1 |        
   40524 | 2021-01-03 07:54:07 |         MASTER-OAFA | (15h 37m 15.85s , -32d 37m 51.2s) |   C |    60 | 17.3 |        
   40603 | 2021-01-03 07:55:27 |         MASTER-OAFA | (15h 46m 40.83s , -32d 37m 04.2s) |   C |    60 | 17.2 |        
   40683 | 2021-01-03 07:56:47 |         MASTER-OAFA | (16h 02m 48.12s , -36d 38m 26.4s) |   C |    60 | 17.1 |        
   40842 | 2021-01-03 07:59:26 |         MASTER-OAFA | (15h 47m 53.41s , -38d 38m 51.7s) |   C |    60 | 17.0 |        
   40928 | 2021-01-03 08:00:52 |         MASTER-OAFA | (15h 57m 59.44s , -38d 37m 42.7s) |   C |    60 | 16.7 |        
   41009 | 2021-01-03 08:02:12 |         MASTER-OAFA | (15h 54m 46.80s , -30d 38m 46.7s) |   C |    60 | 17.0 |        
   41088 | 2021-01-03 08:03:32 |         MASTER-OAFA | (16h 04m 03.97s , -30d 37m 57.6s) |   C |    60 | 16.9 |        
   41406 | 2021-01-03 08:08:50 |         MASTER-OAFA | (15h 33m 02.59s , -36d 38m 51.3s) |   C |    60 | 17.2 |        
   41565 | 2021-01-03 08:11:29 |         MASTER-OAFA | (15h 45m 32.45s , -30d 37m 17.1s) |   C |    60 | 17.3 |        
   41803 | 2021-01-03 08:15:27 |         MASTER-OAFA | (15h 58m 44.22s , -34d 38m 25.6s) |   C |    60 | 17.2 |        
   41883 | 2021-01-03 08:16:47 |         MASTER-OAFA | (16h 08m 22.62s , -34d 37m 38.5s) |   C |    60 | 17.0 |        
   41964 | 2021-01-03 08:18:08 |         MASTER-OAFA | (15h 39m 33.08s , -34d 37m 59.5s) |   C |    60 | 17.4 |        
   42044 | 2021-01-03 08:19:28 |         MASTER-OAFA | (15h 49m 05.56s , -34d 39m 13.0s) |   C |    60 | 17.2 |        
   42123 | 2021-01-03 08:20:47 |         MASTER-OAFA | (15h 56m 11.34s , -32d 39m 21.9s) |   C |    60 | 17.0 |        
   42202 | 2021-01-03 08:22:06 |         MASTER-OAFA | (16h 05m 34.89s , -32d 37m 49.7s) |   C |    60 | 16.8 |        
   42282 | 2021-01-03 08:23:26 |         MASTER-OAFA | (15h 42m 58.96s , -36d 39m 00.0s) |   C |    60 | 17.1 |        
   42361 | 2021-01-03 08:24:45 |         MASTER-OAFA | (15h 52m 54.79s , -36d 37m 30.0s) |   C |    60 | 16.9 |        
   42440 | 2021-01-03 08:26:04 |         MASTER-OAFA | (15h 37m 14.12s , -32d 37m 56.0s) |   C |    60 | 17.2 |        
   42520 | 2021-01-03 08:27:24 |         MASTER-OAFA | (15h 46m 40.09s , -32d 37m 09.0s) |   C |    60 | 16.9 |        
   42600 | 2021-01-03 08:28:43 |         MASTER-OAFA | (16h 02m 47.44s , -36d 38m 32.4s) |   C |    60 | 16.9 |        
   42679 | 2021-01-03 08:30:03 |         MASTER-OAFA | (16h 12m 34.07s , -36d 39m 45.9s) |   C |    60 | 16.7 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB210102B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29230
SUBJECT: GRB 210102B: Swift-XRT observations
DATE:    21/01/03 13:44:24 GMT
FROM:    Paolo D'Avanzo at INAF - OAB  <paolo.davanzo@inaf.it>

D.N. Burrows (PSU), J. D. Gropp (PSU), J.A. Kennea (PSU), J.P. Osborne
(U. Leicester), K.L. Page (U. Leicester), A. Melandri (INAF-OAB), T.
Sbarrato (INAF-OAB), P. D'Avanzo (INAF-OAB) and P.A. Evans (U.
Leicester) report on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the MAXI-detected
burst GRB 210102B (Guo et al. GCN Circ. 29223) in a series of
observations tiled on the sky. The total exposure time is 1.3 ks,
distributed over 7 tiles; the maximum exposure at a single sky location
was 406 s. The data were collected between T0+19.7 ks and T0+26.0 ks,
and are entirely in Photon Counting (PC) mode. 

One uncatalogued X-ray source has been detected, 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 1:
  RA (J2000):  353.8173  =  23:35:16.14
  Dec (J2000): -21.0821  =  -21:04:55.6
  Error: 5.5 arcsec (radius, 90% conf.)
  Count-rate: 0.030 [+0.016, -0.012] ct s^-1   
  Distance: 1289 arcsec from MAXI position.

The results of the XRT-team automatic analysis of the tiled XRT
observations, including a position-specific upper limit calculator, are
available at https://www.swift.ac.uk/xrt_products/TILED_GRB00097.

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


GRB_name: GRB210102C
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29231
SUBJECT: GRB 210102C: Swift-BAT refined analysis
DATE:    21/01/03 23:41:32 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

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

Using the data set from T-240 to T+537 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 210102C (trigger #1015728)
(Troja et al., GCN Circ. 29226).  The BAT ground-calculated position is
RA, Dec = 235.747, -37.231 deg which is
   RA(J2000)  =  15h 42m 59.2s
   Dec(J2000) = -37d 13' 52.2"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 76%.

The mask-weighted light curve shows a double-peaked structure. The first
peak starts at ~T-2 s, peaks at ~T0, and ends at ~T+8 s. The second peak
starts at ~T+55 s, peaks at ~T+67 s, and ends at ~T+100 s. T90 (15-350 keV)
is 87.25 +- 4.97 sec (estimated error including systematics).

The time-averaged spectrum from T-2.07 to T+97.42 sec is best fit by
a simple power-law model.  The power law index of the time-averaged
spectrum is 1.87 +- 0.08.  The fluence in the 15-150 keV band is
3.9 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from
T+66.72 sec in the 15-150 keV band is 4.4 +- 0.3 ph/cm2/sec.  All the
quoted errors are at the 90% confidence level.

The results of the batgrbproduct analysis are available at
https://swift.gsfc.nasa.gov/results/BATbursts/1015728/bascript/top.html


GRB_name: GRB210104A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29232
SUBJECT: GRB 210104A: Fermi GBM Final Real-time Localization
DATE:    21/01/04 11:37:17 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 11:26:59 UT on 4 Jan 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210104A (trigger 631452424.865632 / 210104477).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 107.9, Dec = 67.1 (J2000 degrees, equivalent to J2000 07h 11m, 67d 05'), with a statistical uncertainty of 2.9 degrees.

The angle from the Fermi LAT boresight is 135.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210104477/quicklook/glg_skymap_all_bn210104477.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/bn210104477/quicklook/glg_healpix_all_bn210104477.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210104477/quicklook/glg_lc_medres34_bn210104477.gif


GRB_name: GRB210104A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29233
SUBJECT: GRB 210104A: Swift detection of a burst with a bright optical counterpart
DATE:    21/01/04 11:41:25 GMT
FROM:    Kim Page at U.of Leicester  <klp5@leicester.ac.uk>

E. Troja (NASA/GSFC/UMCP), M. G. Bernardini (INAF-OAB),
A. A. Breeveld (UCL-MSSL), P. D'Avanzo (INAF-OAB),
P. A. Evans (U Leicester), C. Gronwall (PSU), J.D. Gropp (PSU),
A. Y. Lien (GSFC/UMBC), A. Melandri (INAF-OAB),
K. L. Page (U Leicester) and T. Sbarrato (INAF-OAB) report on behalf
of the Neil Gehrels Swift Observatory Team:

At 11:26:59 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210104A (trigger=1015873).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 103.705, +64.661 which is 
   RA(J2000) = 06h 54m 49s
   Dec(J2000) = +64d 39' 39"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a multi-peaked
structure with a duration of about 40 sec.  The peak count rate
was ~16000 counts/sec (15-350 keV), at ~21 sec after the trigger. 

The XRT began observing the field at 11:28:01.8 UT, 62.7 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 103.7707, 64.6743 which is equivalent to:
   RA(J2000)  = 06h 55m 4.97s
   Dec(J2000) = +64d 40' 27.5"
with an uncertainty of 5.3 arcseconds (radius, 90% containment). This
location is 111 arcseconds from the BAT onboard position, within the
BAT error circle. No event data are yet available to determine the
column density using X-ray spectroscopy. 

The initial flux in the 2.5 s image was 1.41e-09 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of nominal 150.0 seconds with the White
filter starting 70 seconds after the BAT trigger. There is a candidate
afterglow in the list of sources generated on-board at
RA(J2000) = 06:55:05.25 = 103.77188
DEC(J2000) = +64:40:34.0 = 64.67611
with a 90%-confidence error radius of about 1.10 arc sec. This position is 6.7
arc sec. from the center of the XRT error circle. The estimated magnitude is
15.52. No correction has been made for the expected extinction corresponding to
E(B-V) of 0.04. 

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: GRB210104A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29234
SUBJECT: GRB 210104A: BALROG localization (Fermi Trigger 631452424 / GRB 210104477)
DATE:    21/01/04 12:00:07 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
631452424 at 11:26:59 on 04 Jan. 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) = 102.7+/-5.4 deg
Decl.(2000.0) = 69.8+/-1.3 deg
We estimate an additional systematic error of 1 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB210104477/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB210104477/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB210104477/json

                        


GRB_name: GRB210104A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29235
SUBJECT: GRB 210104A:  GWAC-F60A optical afterglow observations
DATE:    21/01/04 12:00:26 GMT
FROM:    Liping Xin at NAOC, SVOM  <xlp@nao.cas.cn>

L. P. Xin(NAOC),  J. Wang(GXU), X. H. Han(NAOC), J. Y. Wei(NAOC), 
G. W. LI(NAOC),  L. H. Li(NAOC), C. Wu(NAOC),  X. G. Wang(GXU), 
E. W. Liang (GXU), R. S. Zhang(NAOC), Y. L. Qiu(NAOC), 
and J. S. Deng(NAOC) report: 

We began to observe GRB 210104A (Troja et al., GCN 29233)
with Xinglong GWAC-F60A telescope, China, 
at 11:28:00 (UT), 4th. Jan. 2021, about 61 sec after the burst.

A series of  R, I, and B band images were obtained.
The optical afterglow (Troja et al., GCN 29233) 
was clear detected in our images. 

The brightness is about 14.5 mag in R band at 71 sec after the burst,
calibrated to the USNO B1.0 catalog.

The observations are continuing


GRB_name: GRB210104A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29236
SUBJECT: GRB 210104A: BOOTES-4/MET early optical afterglow detection
DATE:    21/01/04 12:05:43 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

Y.-D. Hu, E. Fernandez-Garcia, A. J. Castro-Tirado, M.D. Caballero-Garcia, M. A. Castro Tirado (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 210104A by Swift (Troja et al. GCNC 29233) and Fermi (Fermi GBM team GCNC 29232, Biltzinger et al. GCNC 29234), the 0.6m BOOTES-4/MET robotic telescope at Lijiang Astronomical Observatory (China) started to gather images in clear filter starting at 2021-01-04 11:27:52 UT (~53 s after trigger). The optical afterglow reported by Swift/UVOT (Troja et al. GCNC 29233) is detected with a magnitude of 15.15+-0.15 in the first 5 s exposure image. Additional observations are ongoing."

We thank the staff at Lijiang observatory for their excellent support.


GRB_name: GRB210104A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29237
SUBJECT: GRB 210104A: MITSuME Akeno optical observation
DATE:    21/01/04 12:44:41 GMT
FROM:    Ryohei Hosokawa at Tokyo Institute of Technology  <hosokawa@hp.phys.titech.ac.jp>

R. Hosokawa, R. Adachi, M. Niwano, K. L. Murata, F. Ogawa, N.
Nakamura, N. Ito, S. Ogata, H. Takamatsu, H. Hara, Y. Yatsu, and N.
Kawai (TokyoTech) report on behalf of the MITSuME collaboration:

We observed the field of GRB 210104A (The Fermi GBM team
, GCN 29232, E. Troja et al., GCN 29233, B. Biltzinger et al., GCN 29234) with
the optical three color (g', Rc, and Ic) CCD cameras attached to the
MITSuME 50 cm telescope of Akeno Observatory, Yamanashi, Japan.
The observation started at 2021-01-04 11:27:54 UT (55s after Swift BAT
trigger). We detected the point source at the position consistent with
the afterglow detected previously(E. Troja et al., GCN 29233, L. P.
Xin et al., GCN 29235, Y.-D. Hu et al., GCN 29236).
We measured the magnitudes as follows.

T0+[sec] MID-UT T-EXP[sec] measured magnitudes
------------------------------------------------------------------------------------------------
55 11:28:24 60 g'=14.6+/-0.1, Rc=14.2+/-0.1, Ic=13.8+/-0.1
------------------------------------------------------------------------------------------------
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.,
https://doi.org/10.1093/pasj/psaa091,
https://arxiv.org/abs/2008.11486; https://github.com/MNiwano/Eclaire).


GRB_name: GRB210104A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29238
SUBJECT: GRB 210104A: Assy optical observations
DATE:    21/01/04 14:22:05 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

V. Kim (FAI, Pulkovo Observatory), A. Pozanenko (IKI),  M. Krugov (FAI), 
S. Belkin (IKI)  report on behalf of GRB-IKI-FuN:

We observed the GRB 210104A (Fermi GBM team, GCN 29232; Troja et al., 
GCN  29233) with AZT-20 telescope of Assy-Turgen observatory starting on 
  Jan. 04 (UT) 12:55:33 in r'-filter.  We detect the optical afterglow 
(Troja et al., GCN  29233; Xin et al., GCN 29235; Hu et al., GCN 29236; 
Hosokawa et al., GCN  29237).

Preliminary photometry of the afterglow obtained in a few initial 
imaging is following

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

2021-04-01 12:55:33  0.0632  r'(AB)  5*60   17.97 0.06   22.7

The photometry is based on nearby stars of PanSTARRS-PS1.
Observations is continuing.


GRB_name: GRB210104A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29239
SUBJECT: Fermi GRB 210104A: Global MASTER-Net observations report 
DATE:    21/01/04 15:30:28 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-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 210104A ( Fermi GBM team, GCN 29232) errorbox  13896 sec after notice time and 13949 sec after trigger time at 2021-01-04 15:19:29 UT, with upper limit up to  18.0 mag. Observations started at twilight.  The observations began at zenith distance = 51 deg. The sun  altitude  is -10.7 deg. 

The galactic latitude b = 27 deg., longitude l = 149 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1518462

We obtain a following upper limits.  

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

   13980 | 2021-01-04 15:19:29 |      MASTER-Tavrida | (06h 52m 09.73s , +68d 11m 37.6s) |   C |    60 | 17.7 |        
   13980 | 2021-01-04 15:19:29 |      MASTER-Tavrida | (07h 08m 11.29s , +68d 09m 51.0s) |   C |    60 | 17.9 |        
   14060 | 2021-01-04 15:20:49 |      MASTER-Tavrida | (06h 59m 02.10s , +66d 11m 00.3s) |   C |    60 | 17.7 |        
   14060 | 2021-01-04 15:20:49 |      MASTER-Tavrida | (07h 13m 46.16s , +66d 09m 08.7s) |   C |    60 | 18.0 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB210102B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29240
SUBJECT: GRB 210102B: Assy optical observations
DATE:    21/01/04 18:06:38 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

A. Pozanenko (IKI), S. Belkin (IKI), V. Kim (FAI, Pulkovo Observatory), 
  M. Krugov (FAI)  report on behalf of GRB IKI FuN:

We observed MAXI GRB 210102B (Guo et al., GCN 29223) with AZT-20 
telescope of Assy-Turgen observatory starting on  Jan. 03 (UT) 13:00:53. 
i.e.  ~1.6 days after trigger.  At the place of the only one of XRT 
candidates (Burrows  et al., GCN 29230) in the localization area of MAXI 
(Guo et al., GCN 29223) we clearly detect the optical object in 
coordinates (J2000) 23:35:15.88 -21:04:55.5 with uncertainness of 0.6 
arcsec in both coordinates.
Preliminary photometry of the object  is following

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

2021-01-03 13:00:53  1.19068  r'(AB)  75*60  22.2 0.2   23.0

The photometry is based on the stars of PanSTARRS-PS1
RA DEC r'
23:35:20.67802 -21:04:16.4688 19.656
23:35:47.99017 -21:11:53.6544 17.807

At this tome we cannot confirm variability of the source. We can suggest 
the object might  be related to GRB 210102B.


GRB_name: GRB210104A
Detection_method: MITSuME
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29241
SUBJECT: GRB 210104A: MITSuME Ishigaki optical observation
DATE:    21/01/04 20:02:05 GMT
FROM:    Takashi Horiuchi at Ishigakijima Astronomical Obs  <takashi.horiuchi@nao.ac.jp>

Takashi Horiuchi, Hidekazu Hanayama (NAOJ), Katsuhiro L. Murata,
Yoichi Yatsu, Nobuyuki Kawai (Tokyo Tech) report on behalf of the
MITSuME collaboration:

We observed the field of GRB 210104A (The Fermi GBM team,
GCN 29232, E. Troja et al., GCN 29233) with the optical three
color (g', Rc, and Ic) CCD cameras attached to the 105 cm
Murikabushi telescope of Ishigakijima Astronomical Observatory,
Okinawa, Japan.

The observation with a series of 60 sec exposures started on
2021-01-04 13:58:34 UT (150 min after Swift BAT trigger).
We detected the point source at the position consistent with
the afterglow reported by Swift UVOT and obtained the
magnitudes as follows.

T0+[min] MID-UT T-EXP[sec] measured magnitudes
------------------------------------------------------------------------------------------------
150 2021-01-04T14:14:02 1500  g'=19.17+/-0.08, Rc=18.12+/-0.04, Ic=17.96+/-0.09
------------------------------------------------------------------------------------------------
T0+ : Elapsed time after the burst
T-EXP: Total Exposure time
The SDSS catalog (DR16) is used for flux calibration.


GRB_name: GRB210104B
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29243
SUBJECT: GRB 210104B: Swift detection of a burst
DATE:    21/01/04 21:24:45 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

S. Laha (GSFC/UMBC/CRESST), M. G. Bernardini (INAF-OAB),
A. A. Breeveld (UCL-MSSL), P. D'Avanzo (INAF-OAB), C. Gronwall (PSU),
J.D. Gropp (PSU), J. A. Kennea (PSU), N. J. Klingler (PSU),
A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC),
A. Melandri (INAF-OAB), M. J. Moss (GWU), K. L. Page (U Leicester),
D. M. Palmer (LANL), T. Sbarrato (INAF-OAB) and M. H. Siegel (PSU)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 21:10:10 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210104B (trigger=1015919).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 53.601, +37.931 which is 
   RA(J2000) = 03h 34m 24s
   Dec(J2000) = +37d 55' 51"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a double-peaked
structure with a duration of about 30 sec.  The peak count rate
was ~1000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

The XRT began observing the field at 21:11:31.2 UT, 80.5 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 53.5539, 37.9302 which
is equivalent to:
   RA(J2000)  = 03h 34m 12.93s
   Dec(J2000) = +37d 55' 48.7"
with an uncertainty of 2.5 arcseconds (radius, 90% containment). This
location is 133 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 in excess of the Galactic value (2.67 x
10^21 cm^-2, Willingale et al. 2013), with an excess column of 1.6
(+1.04/-0.80) x 10^22 cm^-2 (90% confidence). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 83 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 0.79. 

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: GRB210102B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29244
SUBJECT: GRB 210102B: Tiled Swift observations
DATE:    21/01/04 21:35:37 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 series of observations, tiled on the sky, of the
MAXI GRB 210102B. Automated analysis of the XRT data will
be presented online at http://www.swift.ac.uk/xrt_products/TILED_GRB00098

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. The probability of finding
serendipitous sources, unrelated to the MAXI event is high: 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: GRB210104A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29245
SUBJECT: GRB 210104A: Enhanced Swift-XRT position
DATE:    21/01/04 21:54:22 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 2419 s of XRT Photon Counting mode data and 4 UVOT
images for GRB 210104A, 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 = 103.77281, +64.67604 which is equivalent
to:

RA (J2000): 06h 55m 5.47s
Dec (J2000): +64d 40' 33.8"

with an uncertainty of 1.4 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: GRB210104A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29246
SUBJECT: GRB 210104A: Fermi GBM detection
DATE:    21/01/04 22:13:38 GMT
FROM:    Christian Malacaria at NASA-MSFC/USRA  <cmalacaria@usra.edu>

C. Malacaria (NASA-MSFC/USRA), C. Fletcher (USRA) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 11:26:59.87 UT on 04 January 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210104A (trigger 631452424 / 210104477).
which was also detected by the Swift/BAT (Troja et al. 2021, GCN 29233)
The Fermi GBM Final Real-time Localization (GCN 29232) is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 134 degrees.

The GBM light curve roughly consists of three separated peaks
with a duration (T90) of about 32 s (50-300 keV).
The time-averaged spectrum of each peak is best fit by 
a power law function with an exponential high-energy cutoff.
For the first peak, from T0-3.1 s to T0+9.2 s, 
the power law index is -1.2 +/- 0.1 and
the cutoff energy, parameterized as Epeak, is 155 +/- 21 keV.
For the second peak, from T0+16.4 s to T0+22.5 s, 
the power law index is -0.92 +/- 0.1 and Epeak is 245 +/- 23 keV.
For the third peak, from T0+24.6 s to T0+33.8 s,
the power law index is -1.1 +/- 0.1 and Epeak is 199 +/- 14 keV.

The event fluence values (10-1000 keV) in the first, second and third time interval are
(4.004 +/- 0.270)E-06, (5.350 +/- 0.246)E-06 and 
(8.266 +/- 0.276)E-06 erg/cm^2, respectively. 
The 1-sec peak photon flux measured
starting from T0+19.7 s in the 10-1000 keV band
is 17.2 +/- 0.6 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: GRB210104A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29247
SUBJECT: GRB 210104A: Swift/UVOT Detection
DATE:    21/01/04 22:21:25 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (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 210104A 71 s after the BAT trigger 
(Troja et al., GCN Circ. 29233).
A fading source is detected in all UVOT filters in the initial exposures, at the position given in 
Troja et al., (GCN Circ. 29233), and also seen by others (Xin et al., GCN Circ. 29235; Hosokawa et 
al., GCN Circ. 29237; Kim et al., GCN Circ. 29238; Lipunov et al., GCN Circ. 29239 and Horiuchi et 
al., GCN Circ. 29241).

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

white_FC            71          221          147         14.61 Â± 0.02
white              562          582           20         16.23 Â± 0.05
white             1512         1706           39         17.02 Â± 0.05

b                  538          558           20         16.59 Â± 0.10
u_FC               283          533          246         15.28 Â± 0.03
v                  613          632           20         16.36 Â± 0.16
uvw1               662          682           20         16.12 Â± 0.16
uvm2               637          657           20         16.58 Â± 0.25
uvw2               588          608           20         17.09 Â± 0.26

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of 
E(B-V) = 0.04 in the direction of the burst (Schlegel et al. 1998).


GRB_name: GRB210104A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29248
SUBJECT: GRB 210104A: MASTER OT rebrightening  detection
DATE:    21/01/04 22:48:33 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E.Gorbovskoy, N.Tiurina,P.Balanutsa,F.Balakin, 
V.Vladimirov, A.Kuznetsov,K.Zhirkov,D. Vlasenko, I.Gorbunov, D.Zimnukhov, V.Senik,
A.Chasovnikov,A.Pozdnyakov,V.Topolev, D.Cheryasov(Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico FelixAguilar 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, Yu. Sergienko (Blagoveschensk Educational StateUniversity)

MASTER-Tavrida robotic telescope
(Global MASTER-Net http://observ.pereplet.ru, Lipunov et al. 2010, Advances in Astronomy,v.2010,30L)
started (Lipunov et al. GCN 29239)
inspect of Fermi and Swift GRB 210104A (Fermi GCN 29232, 29246;Ttrig=11:26:59;
Swift GCN Troja et al. GCN 29233,Beardmore et al. GCN 29245, Breeveld et al. GCN 29247 ;
Barthelmy https://gcn.gsfc.nasa.gov/other/210104A.gcn3 )
at sunset at Lomonosov MSU Crimean observatory at 2021-01-04 15:19:29 UT.

We detect rebrightening of OT (discovered by Swift GCN 29233 and observed by Xin et al., GCN Circ. 29235; Hosokawa etal. GCN 29237; Kim et al. GCN 29238;
Lipunov et al. GCN 29239, Horiuchi et al. GCN 29241, Breeveld et al. GCN 29247)
MASTER OT J065505.45+644035.0 at 2021-01-04 15:48:32UT with unfiltered 
m_OT=17.3.

The message may be cited.


GRB_name: GRB210104B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29249
SUBJECT: GRB 210104B: BOOTES network optical upper limit
DATE:    21/01/04 23:20:22 GMT
FROM:    Youdong HU at IAA-CSIC  <huyoudong072@hotmail.com>

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

Following the Swift trigger of GRB 210104B (Laha et al., GCNC 29243), the 0.3m BOOTES-1B robotic telescope in Mazagon (Huelva), southern Spain, automatically responded to this burst. Series images were taken started 2021-01-04 21:11:00 UT (~50 s after trigger). In the co-added of 10x10 s images, no source is detected within the XRT position (Laha et al., GCNC 29243) which down to 18.1 mag (clear filter).

The 0.6m BOOTES-2/TELMA robotic telescope at IHSM La Mayora (UMA-CSIC) in Algarrobo Costa (Malaga, Spain) also automatically responded to the Swift trigger of GRB 210104B (Laha et al., GCNC 29243). A series of images were taken starting on 2021-01-04 21:11:24 UT (~74 s after trigger). No optical source is detected within the XRT position on the co-added image (10x10 s, clear filter) which down to 19.9 mag.

Those non-detections are consistent with the reports from Swift (Laha et al., GCNC 29243) and MASTER-Net (Lipunov et al., GCNC 29242). Additional observations are ongoing. We thank the staff at INTA-CEDEA and La Mayora for their excellent support.


GRB_name: GRB210104B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29250
SUBJECT: GRB 210104B: Nanshan/NEXT optical upper limit
DATE:    21/01/05 00:33:27 GMT
FROM:    Dong Xu at NAOC/CAS  <dxu@nao.cas.cn>

S.Y. Fu (NAOC), Z.P. Zhu (NAOC, HUST), X. Liu, D. Xu (NAOC), X. Gao 
(Urumqi No.1 Senior High School), J.Z. Liu (XAO) report:

We observed the field of GRB 210104B (Laha et al., GCN 29243) using the 
NEXT-0.6m optical telescope located at Nanshan, Xinjiang, China. 
Observations automatically started at  UT on 2020-12-21, i.e., 75 s 
after the BAT trigger. We obtained a series of 40 s, 60 s and 90 s 
frames in the Sloan r-filter.

No optical source is detected in our stacked image at the Swift/XRT 
position (Laha et al., GCN 29243), down to a limiting magnitude of 
r~21.0, calibrated with the nearby PanSTARRS field.


GRB_name: GRB210104A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29251
SUBJECT: GRB 210104A: Swift-BAT refined analysis
DATE:    21/01/05 02:33:46 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 (GSFC/UMBC), C. B. Markwardt (GSFC),
T. Sakamoto (AGU), M. Stamatikos (OSU),
E. Troja (NASA/GSFC/UMCP), T. N. Ukwatta (LANL)
(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 210104A (trigger #1015873)
(Troja et al., GCN Circ. 29233).  The BAT ground-calculated position is
RA, Dec = 103.771, 64.675 deg which is
   RA(J2000)  =  06h 55m 04.9s
   Dec(J2000) = +64d 40' 30.6"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 82%.

The mask-weighted light curve shows a multi-peaked structure that
starts at ~T-1 s and ends at ~T+45 s. Several prominent peaks occur
at ~T+4 s, ~T+21 s, ~T+27 s, and ~T+34 s, respectively. T90 (15-350 keV)
is 32.06 +- 0.49 sec (estimated error including systematics).

The time-averaged spectrum from T-1.00 to T+45.39 sec is best fit by
a simple power-law model.  The power law index of the time-averaged
spectrum is 1.55 +- 0.04.  The fluence in the 15-150 keV band is
8.8 +- 0.2 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from
T+26.78 sec in the 15-150 keV band is 12.1 +- 0.4 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/1015873/BA/


GRB_name: GRB210104A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29252
SUBJECT: GRB 210104A: Nanshan/NEXT optical powerlaw decay
DATE:    21/01/05 03:04:27 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 210104A (Troja et al., GCN 29233) using the 
NEXT-0.6m optical telescope located at Nanshan, Xinjiang, China. 
Observations started at 11:59:19 UT (i.e., 0.538 hr post-burst) on 
2021-01-04 and ended at 22:34:07 UT (i.e., 11.11 hr post-burst) on 
2021-01-04, and a series of 120 s, 200 s, 300 s Sloan r-band frames were 
obtained.

Preliminary analysis of the data shows that afterglow is decaying as 
F_rband ~ t^(-\alpha), where \alpha = 0.73 since the very beginning of 
our observations.

If the afterglow continues to decay in this way, it would be of r ~ 20.3 
mag at 1 day post-burst, and still bright enough for optical spectroscopy.


GRB_name: GRB210104B
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29253
SUBJECT: GRB 210104B: Enhanced Swift-XRT position
DATE:    21/01/05 03:08:39 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 1436 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 210104B, 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 = 53.55295, +37.93051 which is equivalent
to:

RA (J2000): 03h 34m 12.71s
Dec (J2000): +37d 55' 49.8"

with an uncertainty of 1.9 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: GRB210104A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29254
SUBJECT: GRB 210104A: DOAO optical afterglow observations
DATE:    21/01/05 03:31:37 GMT
FROM:    Gregory SungHak Paek at SNU  <shpaek@astro.snu.ac.kr>

Gregory S.H. Paek (SNU ARC/SNU), Myungshin Im (SNU ARC/SNU), Taewoo Kim,
and Wonseok Kang (DOAO) on behalf of a larger collaboration

We observed the optical counterpart of GRB 210104A (E. Troja et al.,
GCN #29233)
with the 1-m class telescope in Deokheung Optical Astronomy Observatory
(DOAO). We calibrated flux with the SDSS catalog and used an AB magnitude
system.
----------------------------------------------------------
Filter Date-obs[UT]            Exp.time[s] Mag   Mag Error
----------------------------------------------------------
R      2021-01-04T13:37:29.100 300*4       18.34  0.07
I      2021-01-04T13:42:37.050 300*4       18.04  0.05
----------------------------------------------------------
The magnitudes are not corrected for galactic extinction.


GRB_name: GRB210104B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29255
SUBJECT: GRB 210104B: Assy optical upper limit
DATE:    21/01/05 08:34:20 GMT
FROM:    Yerlan Aimuratov at Fesenkov Astrophysical Inst.(FAI)  <aimuratov@aphi.kz>

V. Kim (FAI, Pulkovo), I. Reva (FAI), M. Krugov (FAI), Y. Aimuratov 
(FAI) report:

We observed the field of GRB 210104B (Laha et al., GCN 29243) with 
AZT-20 1.5-m telescope
of Assy-Turgen Observatory (Assy) starting on Jan. 04 (UT) 22:31:15.
We did not find any optical counterpart in our 20x60s stacked image in 
the enhanced
XRT position (Evans et al., GCN 29253) down to an upper limit R~23.2
(see also Hu et al., GCN 29249 and Fu et al., GCN 29250).
Preliminary photometry of the filed is the following:

Date        UT start  t-T0         Filter  Exp.    OT    Err.  
UL(3-sigma) FWHM
                       (mid, days)          (s)                           
   (")
2021-01-04  22:31:15  0.06325      r'      20*60   n/d   n/d   23.2      
   2.3

Further observations on this object are not planned except personal 
request.


GRB_name: GRB210104B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29256
SUBJECT: GRB 210104B: Swift-XRT refined Analysis
DATE:    21/01/05 10:26:27 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 6.2 ks of XRT data for GRB 210104B (Laha et al. GCN
Circ. 29243), from 100 s to 39.8 ks after the  BAT trigger. The data
are entirely in Photon Counting (PC) mode. The enhanced XRT position
for this burst was given by Evans et al. (GCN Circ. 29253).

The light curve can be modelled with a power-law decay with a decay
index of alpha=0.59 (+/-0.04).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.31 (+0.27, -0.25). The
best-fitting absorption column is  1.15 (+0.26, -0.23) x 10^22 cm^-2,
in excess of the Galactic value of 2.7 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 4.3 x 10^-11 (1.3 x 10^-10) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.15 (+0.26, -0.23) x 10^22 cm^-2
Galactic foreground: 2.7 x 10^21 cm^-2
Excess significance: 6.4 sigma
Photon index:      2.31 (+0.27, -0.25)

If the light curve continues to decay with a power-law decay index of
0.59, the count rate at T+24 hours will be 0.019 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 8.4 x
10^-13 (2.4 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01015919.

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


GRB_name: GRB210104A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29257
SUBJECT: GRB 210104A: 1.3m DFOT Optical Afterglow Detection
DATE:    21/01/05 11:38:59 GMT
FROM:    Amit Kumar at ARIES, India  <amitkundu515@gmail.com>

Amit Kumar (ARIES), Rahul Gupta (ARIES), Dimple (ARIES), Ankur Ghosh
(ARIES), Nikita Rawat (ARIES), Brajesh Kumar (ARIES), Vibhore Negi (ARIES),
Amar Aryan (ARIES), Shashi B. Pandey (ARIES), and Kuntal Misra (ARIES)
report:

We observed the optical afterglow of the Fermi (Fermi GBM team GCNC 29232,
Biltzinger et al. GCNC 29234) and Swift detected GRB 210104A (Troja et al.
GCNC 29233) with the 1.3m Devsthal Fast Optical Telescope (DFOT) at
Aryabhatta Research Institute of Observational Sciences (ARIES), Nainital
(India), from 2021-01-04 17:50:11 to 2021-01-04 18:35:28 UTC (from ~6.386
to 7.141 hours after the burst). We observed 10 frames each of 240 seconds
in the Bessell R filter. We clearly detected the optical afterglow of GRB
210104A in all individual frames within the Swift XRT enhanced error circle
(Beardmore et al. 29245) as reported by Xin et al. GCN 29235 and later by
Hu et al. GCN 29236, Hosokawa et al. GCN 29237, Kim et al. GCN 29238,
Takashi et al. GCN 29241, Lipunov et al. GCN 29248, Zhu et al. GCN 29252
and Gregory et al. GCN 29254.

The estimated preliminary magnitude for the first R-band image is as
follows:

T_start-T0 (hours) Start Date (UTC) Filter Magnitude (mag)

-----------------------------------------------------------
-----------------------------------------------------------
6.386 2021-01-04T17:50:11 R 18.95 +- 0.07


Photometry is done based on the USNO-B1.0 catalog. The quoted magnitude is
not corrected for the Galactic extinction in the direction of GRB 210104A.

This message may be cited.


GRB_name: GRB210104A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29258
SUBJECT: Konus-Wind detection of GRB 210104A
DATE:    21/01/05 14:17:49 GMT
FROM:    Dmitry Frederiks at Ioffe Institute  <fred@mail.ioffe.ru>

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

The long GRB 210104A (Swift detection:  Troja et al., GCN 29233;
Fermi GBM detection:  Malacaria et al., GCN 29246)
triggered Konus-Wind (KW) at T0=41224.536 s UT (11:27:04.536).

The burst light curve shows multiple partly overlapped peaks
in the interval from ~T0-2 s to ~T0+33 s.
The emission is seen up to ~2 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB210104_T41224/

As observed by Konus-Wind, the burst had
a fluence of (2.15 Â± 0.35)x10^-5 erg/cm^2 and
a 64-ms peak energy flux, measured from T0+26.624,
of (1.13 Â± 0.19)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+33.024 s)
is best fit in the 20 keV - 20 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -1.00 (-0.16,+0.18),
the high energy photon index beta = -2.52 (-0.52,+0.24),
the peak energy Ep = 157 (-18,+23) keV,
chi2 = 90/97 dof.

The spectrum near the peak count rate (measured from T0+16.640
to T0+33.024 s) is best fit in the 20 keV - 15 MeV range
by the GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.95 (-0.11,+0.11),
the high energy photon index beta = -2.47 (-1.10,+0.24),
the peak energy Ep = 176 (-24,+37) keV,
chi2 = 83/97 dof.

All the quoted errors are estimated at the 90% confidence level.
All the presented results are preliminary.


GRB_name: GRB210104B
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29259
SUBJECT: GRB 210104B: Swift/UVOT Upper Limits
DATE:    21/01/05 14:18:56 GMT
FROM:    Alice Breeveld at MSSL-UCL  <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) 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 210104B 84 s after the BAT trigger 
(Laha et al., GCN Circ. 29243).
No optical afterglow consistent with the XRT position (Evans et al. GCN Circ. 29253) 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            84          234          147         >20.5
u_FC               296          546          246         >19.8
white               84          753          172         >20.7
v                  625          645           19         >17.6
b                  551          743           39         >19.1
u                  296          719          265         >19.9

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of 
E(B-V) = 0.79 in the direction of the burst (Schlegel et al. 1998).


GRB_name: GRB210104A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29260
SUBJECT: GRB 210104A: Swift-XRT refined Analysis
DATE:    21/01/05 14:26:50 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 5.9 ks of XRT data for GRB 210104A (Troja et al. GCN
Circ. 29233), from 69 s to 76.7 ks after the  BAT trigger. The data
comprise 1.8 ks in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Beardmore et al. (GCN Circ. 29245).

The late-time light curve (from T0+6.1 ks) can be modelled with a
power-law decay with a decay index of alpha=1.35 (+0.08, -0.07).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.012 (+/-0.028). The
best-fitting absorption column is  1.10 (+/-0.08) x 10^21 cm^-2, in
excess of the Galactic value of 5.1 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 1.92 (+0.11, -0.10)
and a best-fitting absorption column of 1.24 (+0.31, -0.29) 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 (3.9 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.24 (+0.31, -0.29) x 10^21 cm^-2
Galactic foreground: 5.1 x 10^20 cm^-2
Excess significance: 4.1 sigma
Photon index:      1.92 (+0.11, -0.10)

If the light curve continues to decay with a power-law decay index of
1.35, the count rate at T+24 hours will be 0.047 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.7 x
10^-12 (1.8 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01015873.

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


GRB_name: GRB210105A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29261
SUBJECT: GRB 210105A: Fermi GBM Final Real-time Localization
DATE:    21/01/05 16:13:24 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 LONG GRB

At 16:03:05 UT on 5 Jan 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210105A (trigger 631555390.920328 / 210105669).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 71.0, Dec = -36.8 (J2000 degrees, equivalent to J2000 04h 44m, -36d 47'), with a statistical uncertainty of 9.6 degrees.

The angle from the Fermi LAT boresight is 65.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210105669/quicklook/glg_skymap_all_bn210105669.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/bn210105669/quicklook/glg_healpix_all_bn210105669.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210105669/quicklook/glg_lc_medres34_bn210105669.gif


GRB_name: GRB210104A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29262
SUBJECT: GRB 210104A: early ATLAS detections of the bright afterglow 
DATE:    21/01/05 17:47:51 GMT
FROM:    Stephen Smartt at Queen's U/Belfast  <s.smartt@qub.ac.uk>

S. J. Smartt, K. W. Smith (QUB), S. Srivastav,, D. R.  Young,
M. Fulton, (QUB) L. Denneau, A. Heinze, J.  Tonry, H. Weiland (IfA,
Univ. Hawaii), A. Rest (STScI), B. Stalder (LSST), C. Stubbs
(Harvard), O. McBrien, J. Gillanders, L. Shingles (QUB), 
T.-W. Chen (MPE)

We report serendipitous observations of GRB210104A (Troja et al. GCN
29233) by ATLAS, the twin telescope system on Haleakala and Mauna
Loa that surveys the whole northern sky every 2 days (see Tonry et
al. 2018, PASP, 130f4505).  Optical transients are automatically
detected on the difference images and discoveries (Smith et al. 2020,
PASP, 132h5002) are made public through the IAU Transient Name Server.

During the course of its survey, ATLAS happened to be observing the
field of GRB210104A starting 1min 47sec after the Swift BAT trigger at
2021-01-04 11:26:59 UT (Troja et al. GCN 29233). This was a fortunate
coincidence in normal survey mode and not a triggered pointing.

We detect the bright UVOT afterglow as initially reported in (Troja et
al. GCN 29233), and appear to have the caught it early and bright at
o = 13.9 along with rapid fading (see also Xin et al, GCN29235, Hu et
al. 29236, Hosokawa et al. GCN 29237, Kim et al. GCN 29238, Lipunov et
al. 29239),

It was detected at a position : 
RA = 06:55:05.37 (103.77240) DEC = +64:40:34.2 (+64.67618) 
              
The expoures were 30sec long in the o-band (an r+i composite),
with start time and magnitudes as follows : 

###MJD              UTC                                         m      dm  
59218.478319  2021-01-04 11:28:46.762 UTC 13.94  0.01
59218.481544  2021-01-04 11:33:25.402 UTC 15.56  0.01
59218.487080  2021-01-04 11:41:23.712 UTC 16.43  0.02
59218.497226  2021-01-04 11:56:00.326 UTC 16.96  0.03
59218.670448  2021-01-04 16:05:26.707 UTC >18.4  (3 sigma limit) 


GRB_name: GRB210105A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29264
SUBJECT: Fermi GRB 210105A: Global MASTER-Net observations report 
DATE:    21/01/05 20:30:09 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 210105A ( Fermi GBM team, GCN 29261) errorbox  11240 sec after notice time and 11295 sec after trigger time at 2021-01-05 19:11:21 UT, with upper limit up to  18.5 mag. Observations started at twilight.  The observations began at zenith distance = 77 deg. The sun  altitude  is -11.0 deg. 

The galactic latitude b = -40 deg., longitude l = 239 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1519938

We obtain a following upper limits.  

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

   11326 | 2021-01-05 19:11:21 |          MASTER-IAC | (04h 40m 37.16s , -30d 00m 42.3s) |   C |    60 | 14.9 |        
   11326 | 2021-01-05 19:11:21 |          MASTER-IAC | (04h 31m 18.61s , -29d 56m 05.8s) |   C |    60 | 15.6 |        
   11405 | 2021-01-05 19:12:41 |          MASTER-IAC | (04h 30m 25.22s , -26d 01m 59.9s) |   C |    60 | 16.6 |        
   12227 | 2021-01-05 19:26:23 |          MASTER-IAC | (04h 40m 44.73s , -30d 02m 48.9s) |   C |    60 | 17.0 |        
   12227 | 2021-01-05 19:26:23 |          MASTER-IAC | (04h 31m 25.39s , -29d 58m 12.6s) |   C |    60 | 17.1 |        
   12307 | 2021-01-05 19:27:43 |          MASTER-IAC | (04h 30m 21.85s , -26d 01m 27.7s) |   C |    60 | 18.2 |        
   13048 | 2021-01-05 19:40:04 |          MASTER-IAC | (04h 35m 50.16s , -40d 03m 02.2s) |   C |    60 | 16.9 |        
   13048 | 2021-01-05 19:40:04 |          MASTER-IAC | (04h 25m 17.91s , -39d 58m 24.3s) |   C |    60 | 17.1 |        
   15230 | 2021-01-05 20:16:26 |          MASTER-IAC | (04h 40m 38.58s , -30d 00m 38.9s) |   C |    60 | 18.3 |        
   15230 | 2021-01-05 20:16:26 |          MASTER-IAC | (04h 31m 17.88s , -29d 56m 09.0s) |   C |    60 | 17.8 |        
   15310 | 2021-01-05 20:17:45 |          MASTER-IAC | (04h 30m 26.00s , -26d 02m 02.7s) |   C |    60 | 18.5 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB210104A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29265
SUBJECT: GRB 210104A: Assy continued optical observations
DATE:    21/01/05 22:12:02 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

V. Kim (FAI, Pulkovo Observatory), A. Pozanenko (IKI),  M. Krugov (FAI), 
S. Belkin (IKI), Y. Aimuratov (FAI) report on behalf of GRB IKI FuN:

We continued observations of the GRB 210104A (Fermi GBM team, GCN 29232; 
Troja et al., GCN  29233; Frederiks et al., GCN  29258) with AZT-20 
telescope of Assy-Turgen observatory starting on  Jan. 05 (UT) 12:55:33 
in r'-filter.  We detect the optical afterglow (Troja et al., GCN 
29233; Xin et al., GCN 29235; Hu et al., GCN 29236; Hosokawa et al., GCN 
  29237; Kim et al., GCN 29238; Lipunov et al., GCN 29239; Horiuchi et 
al., GCN 29241; Breeveld et al., GCN 29247; Zhu et al., GCN 29252; Paek 
  et al., GCN 29254; Kumar et al., GCN 29257; Smartt et al., GCN 29262).

Preliminary photometry obtained in images in the beginning of 
observations on Jan. 05 is following

Date       UT start     Filter  Exp.    OT    Err.
                                 (s)

2021-01-04 15:35:27     r'(AB)  20*60   20.85 0.07
2021-01-04 16:20:20     r'(AB)  20*60   21.23 0.10
2021-01-04 17:05:11     r'(AB)  20*60   21.19 0.06

The photometry is based on nearby stars of PanSTARRS-PS1.
Observations are continuing.


GRB_name: GRB210104B
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29266
SUBJECT: GRB 210104B: Swift-BAT refined analysis
DATE:    21/01/05 23:27:10 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

T. Sakamoto (AGU), S. D. Barthelmy (GSFC),
H. A. Krimm (NSF), S. Laha (GSFC/UMBC),
A. Y. Lien (GSFC/UMBC), C. B. Markwardt (GSFC),
D. M. Palmer (LANL), M. Stamatikos (OSU),
T. N. Ukwatta (LANL) (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 210104B (trigger #1015919)
(Laha et al., GCN Circ. 29243).  The BAT ground-calculated position is
RA, Dec = 53.561, 37.951 deg which is
   RA(J2000)  =  03h 34m 14.7s
   Dec(J2000) = +37d 57' 05.1"
with an uncertainty of 1.7 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 59%.

The mask-weighted light curve shows a double peaks structure that starts
at ~T0 and ends at ~T+23 s. The two peaks occurs at ~T0 and ~T+11 s,
respectively. T90 (15-350 keV) is 19.94 +- 2.33 sec (estimated error
including systematics).

The time-averaged spectrum from T-0.15 to T+22.76 sec is best fit
by a simple power-law model.  The power law index of the time-averaged
spectrum is 1.83 +- 0.14.  The fluence in the 15-150 keV band is
1.2 +- 0.1 x 10^-6 erg/cm2. The 1-sec peak photon flux measured from
T+10.83 sec in the 15-150 keV band is 1.9 +- 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/1015919/BA/


GRB_name: GRB210104A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29268
SUBJECT: GRB 210104A: CALET Gamma-Ray Burst Monitor detection
DATE:    21/01/06 10:15:24 GMT
FROM:    Valentin Pal'shin at AGU  <val@phys.aoyama.ac.jp>

M. L. Cherry (LSU),
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, K. Kobayashi (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U), N. Cannady (GSFC/UMBC),
S. Ricciarini (U of Florence), P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The long bright GRB 210104A (Swift detection: Troja et al.,
GCN Circ. 29233, Palmer et al., GCN Circ. 29251;
Fermi GBM detection: Malacaria et al., GCN Circ. 29246;
Konus-Wind detection: Frederiks et al., GCN Circ. 29258;
https://gcn.gsfc.nasa.gov/other/210104A.gcn3) triggered the CALET
Gamma-ray Burst Monitor (CGBM) at 11:26:56.318 UTC on 4 January 2021
(http://cgbm.calet.jp/cgbm_trigger/flight/1293794541/).
The burst signal was seen by all CGBM detectors.

The burst light curve shows multiple partially overlapped pulses which
start at T+2.5 sec and end at T+36.5 sec. The T90 and T50 durations
measured by the SGM data are 31.2 +- 2.0 sec and 11.6 +- 9.4 sec
(40-1000 keV), respectively.

The ground processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1293794541/

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


GRB_name: GRB210104A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29269
SUBJECT: GRB 210104A: iTelescope optical upper limit
DATE:    21/01/06 10:19:18 GMT
FROM:    Filipp Dmitrievich Romanov at Amateur astronomer  <filipp.romanov.27.04.1997@gmail.com>

I observed the field of GRB 210104A (Troja et al., GCN Circ. 29233)
with remote telescope T11 (0.50-m f/6.8 reflector + CCD + f/4.5 focal
reducer) of iTelescope.Net in New Mexico Observatory. Three images
with AstroDon Luminance filter and with 300 seconds exposure time were
obtained on 2021-01-05. Start time of exposures: 06:46:48 UT (~19.3 h.
after trigger; Binx1), 06:52:21 UT (Binx2) and 06:57:44 UT (Binx1). I
did not detect any optical transients (magnitude limit of about 21.0
in stacked image).


GRB_name: GRB210102B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29270
SUBJECT: GRB 210102B: Assy optical afterglow identification
DATE:    21/01/06 15:55:15 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

A. Pozanenko (IKI), S. Belkin (IKI), V. Kim (FAI, Pulkovo Observatory), 
  M. Krugov (FAI)  report on behalf of GRB IKI FuN:

We continued observations of  XRT candidate (Burrows  et al., GCN 29230) 
of MAXI GRB 210102B (Guo et al., GCN 29223) with AZT-20 telescope of 
Assy-Turgen observatory starting on  Jan. 05 (UT) 13:00:53, i.e.  ~3.2 
days after trigger.  At the place of the only one of XRT candidate 
(Burrows  et al., GCN 29230)  we do not detect the optical object found 
early (Pozanenko et al., GCN 29240).
Preliminary photometry of the field is following

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

2021-01-05 13:00:53   3.20177   r'(AB) 76*60  n/d n/d   23.1

The photometry is based on the stars of PanSTARRS-PS1
RA DEC r'
23:35:20.67802 -21:04:16.4688 19.656
23:35:47.99017 -21:11:53.6544 17.807

We confirm the optical object reported in GCN 29240 as an afterglow of 
GRB 210102B.


GRB_name: GRB210102B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29271
SUBJECT: GRB 210102B: further Swift-XRT observations
DATE:    21/01/06 17:28:28 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) 
and A. Y. Lien (GSFC/UMBC) report on behalf of the Swift-XRT team:

Swift-XRT obtained further observations of the field of the MAXI-detected burst GRB 210102B 
(Guo et al. GCN Circ. 29223). The data were collected between T0+209.5 ks and T0+312.5 ks 
for a total exposure time of 2.5 ks, and are entirely in Photon Counting (PC) mode. 

Source 1 (Burrows et al., GCN Circ. 29230) is not detected down to a 3sigma upper limit of 0.004 ct/s. 
The source therefore has faded (with 2.2 sigma significance) with respect to the previous detection level 
(0.030 [+0.016, -0.012] ct s^-1 between T0+19.7 ks and T0+26.0 ks; Burrows et al., GCN Circ. 29230). 

We propose this source as the GRB X-ray afterglow, in agreement with the results of the optical observations 
reported by Pozanenko et al. (GCN Circ. 29270).


GRB_name: GRB210104A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29273
SUBJECT: GRB 210104A: SARA-KP 0.9m Optical Afterglow Detection 
DATE:    21/01/06 22:01:36 GMT
FROM:    Samalka Anandagoda at Clemson University  <iananda@g.clemson.edu>

S. Anandagoda, S. Geier, K. Pellegrin and D. Hartmann report:

We observed the field of GRB 20210104A (Fermi GBM Team, GCN 29232; Troja et al., GCN 29233; Biltzinger et al., GCN 29234) using the SARA 0.9m optical telescope located at Kitt Peak, AZ, USA, equipped with the Alta-E6-1105 camera. Observation started at 06:20:04 UTC on 2021-01-05 and ended at 09:34:43 UTC (~ 18 to 21 hours after the detection of the burst by the Fermi GBM Team). We obtained a series of 120s exposure frames in the Bessell R filter. We clearly detect the optical afterglow of GRB 20210104A at the enhanced Swift-XRT position (Beardmore et al., GCN 29245).

The estimated magnitude of the GRB afterglow was 20.61 found by stacking 20 images of 120s each in the Bessell R band filter.

T_start-T0 (hrs)   T_end-T0 (hrs)     Start Date (UTC)    Filter  Magnitude (mag)
â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”â€”-------------------------
----------------------------------------------------------------------------------------------------------------
18:53        19:33          2021-01-05T06:20:04       R     20.61


Photometry is done based on the USNO-B1.0 catalog.

The Southeastern Association for Research in Astronomy (SARA) consortium operates three telescopes: the 0.9-m SARA-KP at Kitt Peak in Arizona, and the 0.6-m SARA-CT at Cerro Tololo in Chile, and the 1.0-m SARA-RM (formerly the JKT) telescope at Roque de los Muchachos Observatory in the Canary Islands. For more information see: Keel et al. (2016): https://iopscience.iop.org/article/10.1088/1538-3873/129/971/015002


GRB_name: GRB210104A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29274
SUBJECT: GRB210104A: VIRT optical transient detection.
DATE:    21/01/07 05:51:35 GMT
FROM:    Priyadarshini Gokuldass at U. of the Virgin Islands  <priyadass.94@gmail.com>

We observed the field of GRB210104A (The Fermi GBM team, GCN 29232, Troja
et al., GCN 29233) with the 0.5m Virgin Island Robotic Telescope (VIRT) at
the University of the Virgin Islands' Etelman Observatory on 01-05-2021
starting at 23:44:00 UT with a midpoint of observation of T+40 hrs. We
performed a series of exposures in R filter with a total exposure of ~10ks.
The weather conditions were clear during the hours of observation with an
average airmass of 1.7.

We detect a source consistent with the UVOT position (Troja et al., GCN
29233) and optical transient identified by others (e.g., Bilitzinger et
al., GCN 29234, Xin et al., GCN 29235, Hu et al., GCN 29236) with magnitude:

R= 20.8 +/- 0.3

This magnitude is consistent with the powerlaw decay rate of alpha = 0.73
reported by Zhu et al, GCN 29252.

The magnitude is estimated from comparison to nearby USNO B1 stars and is
not corrected for Galactic extinction. Further analysis is in progress. The
VIRT is still in the commissioning phase.

This work is supported by NASA-MUREP-MIRO grant NNX15AP95A, NSF EiR AST
Award 1901296, and NSF HBCU-UP AST Award 1831682. This message can be cited.


GRB_name: GRB210104A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29275
SUBJECT: GRB 210104A: GMG observations
DATE:    21/01/07 08:57:00 GMT
FROM:    Jirong Mao at Yunnan Obs  <jirongmao_obs@ynao.ac.cn>

J. Mao, X. Ding, X.-L. Zhang, and J.-M. Bai (YNAO) report:




We observed the field of GRB 210104A (Troja et al. GCN 29233) with

the 2.4-meter optical telescope at Gao-Mei-Gu (GMG) station of Yunnan

Observatories. The observation began at UT 13:00:11, 4, Jan. 2021, about

1.5 hours after the trigger. We clearly detected the source, and the preliminary

magnitude was measured to be R~17.6. Further analysis of the observations during

the night is ongoing. 


GRB_name: GRB201227A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29276
SUBJECT: GRB 201227A: ASIM observation
DATE:    21/01/07 14:29:38 GMT
FROM:    Martino Marisaldi at U of Bergen, Norway  <martino.marisaldi@uib.no>

M. Marisaldi (University of Bergen), A. Mezentsev (University of Bergen), 
N. Ã˜stgaard (University of Bergen), V. Reglero (University of Valencia) 
and T. Neubert (DTU Space) report on behalf of the ASIM Team:

At 15:14:07.380 UT on 27 December 2020, the Atmosphere-Space Interactions Monitor (ASIM)
mission triggered on the very short and bright GRB 201227A 
(AGILE detection: Ursi et al., GCN Circ. 29179; IPN triangulation: Svinkin et al., GCN Circ. 29182;
Swift observations: Evans, GCN Circ. 29184; Evans, GCN Circ. 29185; Dâ€™Elia et al., GCN Circ. 29202;
Insight-HXMT/HE detection: Xiao et al., GCN Circ. 29187; Konus-Wind observation:  Svinkin et al., GCN Circ. 29196;
Fermi GBM observation: Lesage et al., GCN Circ. 29206; GRAWITA VST observation: Izzo et al., GCN Circ. 29207
Chilescope observation:  Belkin et al., GCN Circ. 29208)

Photon by photon data with <1 microsecond time resolution have been
collected for a time interval of two seconds centered at the trigger time.
As seen by the Modular X- and Gamma-Ray Sensor (MXGS) onboard ASIM
the burst consists of a single emission episode about 60 ms in duration, with evidence of time variability. 
The emission is detected in the MXGS High Energy Detector (HED), 
sensitive in the range 0.3 to >30 MeV.  
Significant emission is observed up to about 3 MeV. 
The MXGS Low Energy Detector (LED), sensitive in the range 0.05 to 0.4 MeV, 
was not active at trigger time.

ASIM is an ESA mission onboard the International Space Station dedicated to the 
observation of Terrestrial Gamma-ray Flashes (TGFs) and Transient Luminous Events (TLEs) 
operative since June 2018 (Neubert et al., Space Sci Rev (2019) 215:26 
https://doi.org/10.1007/s11214-019-0592-z <https://doi.org/10.1007/s11214-019-0592-z>  ). 
The payload includes the Modular X- and Gamma-Ray Sensor (MXGS) 
(Ã˜stgaard et al., Space Sci Rev (2019) 215:23 https://doi.org/10.1007/s11214-018-0573-7 <https://doi.org/10.1007/s11214-018-0573-7>  ), 
and the the Modular Multispectral Imaging Array  (MMIA) 
(Chanrion et al., Space Sci Rev (2019) 215:28 https://doi.org/10.1007/s11214-019-0593-y <https://doi.org/10.1007/s11214-019-0593-y>  ). 
The ASIM Science Data Centre (ASDC) website is https://asdc.space.dtu.dk/ <https://asdc.space.dtu.dk/>


GRB_name: GRB210104A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29277
SUBJECT: GRB 210104A: SAO RAS optical observations
DATE:    21/01/07 15:00:45 GMT
FROM:    Moskvitin Alexander at SAO RAS  <mosk@sao.ru>

A. S. Moskvitin, V. V. Vlasyuk (SAO RAS)
on behalf of GRB follow-up team report.

We observed the field of the GRB 210104A (Fermi GBM Team, GCN #29232;
Troja et al., GCN #29233; Biltzinger et al., GCN #29234)
with the 0.5m Astrosib RC500-2 telescope of SAO RAS
equipped with the Rc filter and FLI Proline PL16801 camera.
The observations carried out on 2021 Jan. 4, 0.32--0.38 days
after the trigger (T_mid - T0 = 0.35d).


In the 37 x 20 sec. stacked image we clearly detect the GRB OT
(Troja et al., GCN #29233; Xin et al., GCN #29235; Hu et al.,
GCN #29236; Hosokawa et al., GCN #29237; Kim et al., GCN #29238;
Lipunov et al., GCN #29239; Horiuchi et al., GCN #29241;
Breeveld et al., GCN #29247; Zhu et al., GCN #29252; Paek et al.,
GCN #29254; Kumar et al., GCN #29257; Smartt et al., GCN #29262;
V. Kim, GCN #29265; S. Anandagoda, GCN #29273; P. Gokuldass,
GCN #29274; J. Mao, GCN #29275)
with the brightness of R = 19.4 +/- 0.1. The preliminary photometry
is based on R2 magnitudes of nearby USNO-B1 stars.


GRB_name: GRB201216C
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29278
SUBJECT: GRB 201216C: Swift-XRT refined Analysis
DATE:    21/01/08 02:49:56 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), M.G. Bernardini
(INAF-OAB), E. Ambrosi (INAF-IASFPA) , M. Capalbi (INAF-IASFPA), A.
Tohuvavohu (U. Toronto), B. Sbarufatti (PSU), D.N. Burrows (PSU) and
A.P. Beardmore report on behalf of the Swift-XRT team:

We have analysed 2.8 ks of XRT data for GRB 201216C (Beardmore et al.
GCN Circ. 29061), from 3.0 ks to 1896.5 ks after the  BAT trigger. The
data comprise 466 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. 29067).

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.97 (+0.10, -0.09).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.35 (+0.17, -0.16). The
best-fitting absorption column is  7.7 (+1.2, -1.1) x 10^21 cm^-2, in
excess of the Galactic value of 5.0 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.03 (+0.16, -0.15)
and a best-fitting absorption column of 5.6 (+1.0, -0.9) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 4.2 x 10^-11 (8.0 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      5.6 (+1.0, -0.9) x 10^21 cm^-2
Galactic foreground: 5.0 x 10^20 cm^-2
Excess significance: 9.3 sigma
Photon index:      2.03 (+0.16, -0.15)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01013243.

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


GRB_name: GRB210108A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29279
SUBJECT: GRB 210108A: BALROG localization (Fermi Trigger 631793415 / GRB 210108424)
DATE:    21/01/08 10:33:14 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
631793415 at 10:10:10 on 08 Jan. 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) = 306.9+/-4.3 deg
Decl.(2000.0) = -27.6+/-2.5 deg
We estimate an additional systematic error of 1 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB210108424/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB210108424/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB210108424/json

                        


GRB_name: GRB201216C
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29280
SUBJECT: Correction to GCN 29278: GRB 201216C XRT refined analysis
DATE:    21/01/08 11:59:30 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

The XRT refined analysis of GRB 201216C contained in GCN Circ. 29278
was incorrect, some of the data had been excluded from the analysis.
The corrected analysis is below.

We apologise for the confusion.


We have analysed 5.2 ks of XRT data for GRB 201216C (Beardmore et al.
GCN Circ. 29061), from 3.0 ks to 1938.0 ks after the  BAT trigger. The
data comprise 466 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. 29067).

The light curve can be modelled with an initial power-law decay with an
index of alpha=2.09 (+0.16, -0.10), followed by a break at T+9078 s to
an alpha of 1.07 (+0.15, -0.10).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index  of 2.35 (+0.17, -0.16). The
best-fitting absorption column is  7.7 (+1.2, -1.1) x 10^21 cm^-2, in
excess of the Galactic value of 5.0 x 10^20 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.03 (+0.16, -0.15)
and a best-fitting absorption column of 5.6 (+1.0, -0.9) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 4.2 x 10^-11 (8.0 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:        5.6 (+1.0, -0.9) x 10^21 cm^-2
Galactic foreground: 5.0 x 10^20 cm^-2
Excess significance: 9.3 sigma
Photon index:        2.03 (+0.16, -0.15)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01013243.


GRB_name: GRB201227A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29281
SUBJECT: GRB 201227A: continued Chilescope confirmation of variability of possible optical counterpart, redshift estimating
DATE:    21/01/08 16:20:33 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI), A. Pozanenko (IKI), P. Minaev (IKI), M. Krugov (FAI)
report on behalf of GRB IKI FuN collaboration:

We continued observations of the field of XRT #2 sources (D'Elia et al.,
GCN 29202) (hereafter X2) found in IPN localization area (Svinkin et
al., GCN 29182) of GRB 201227A (Ursi et al., GCN 29179; Xiao et al., GCN
29187; Svinkin et al., GCN 29196; Lesage et al., GCN 29206; Marisaldi et 
al., GCN 29276) with Chilescope RC-1000 on 2021-01-01 and 2021-01-08 in 
r'-filter.

The X2_O2 object found in previous observation on 2020-12-29 at r'(AB)=
20.5 (Belkin et al., GCN 29208; see also Izzo et al., GCN 29207) is not
detected on 2021-01-01 with an upper limit of r'(AB) > 20.6 and barely
detected on 2021-01-08 at r'(AB)=22.6. Now we confirm the variability of
the object of X2_O2 and suggest the optical object X2_02 could be a
counterpart of GRB 201227A. In the last image on 2021-01-08, the object 
X2_O2 could be the host galaxy. A finding chart of the X2_O2 can be found in

http://grb.rssi.ru/GRB201227A/GRB201227A_r_FC_201229_2100108.png

Preliminary photometry of the X2_O2 is following

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

2021-01-01 05:57:21 4.63072 r' 5*600  n/d    n/d  20.6   1.5"
2021-01-08 04:15:45 11.5636 r' 3*1200 22.6   0.4  22.5   1.4"

The photometry is based on nearby stars from the APASS_DR8

RA DEC r
11:19:31.40904 -73:35:47.6880 14.090
11:19:44.89128 -73:34:49.6092 15.180
11:19:36.65304 -73:36:30.2112 15.307

In addition we investigated a position of the GRB 201227A on the EHD 
diagram (see Minaev et al., MNRAS, 492,  1919, 2020). The position of 
GRB 201227A based on Konus-Wind data (Svinkin et al., GCN Circ. 29196) 
can be found in

http://grb.rssi.ru/GRB201227A/GRB201227A_EH_T90i.png

We can exclude the GRB 201227A as a giant flare event of SGR since there 
is no nearby galaxies in the IPN error box. We can identify the GRB 
201227A as short GRB at a redshift of z > 0.05.


GRB_name: GRB210109A
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29282
SUBJECT: GRB 210109A: MAXI/GSC detection
DATE:    21/01/09 12:21:51 GMT
FROM:    Hitoshi Negoro at Nihon U  <negoro.hitoshi@nihon-u.ac.jp>

R. Uematsu (Kyoto U.), H. Negoro (Nihon U.), M. Serino (AGU), 
M. Nakajima, M. Aoki, K. Kobayashi, R. Takagi, K, Asakura, K, Seino (Nihon U.),
T. Mihara, T. Tamagawa, M. Matsuoka (RIKEN),
T. Sakamoto, S. Sugita, H. Nishida, K. Komachi, A. Yoshida (AGU),
Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, Y. Okamoto, S. Kitakoga (Chuo U.),
M. Shidatsu (Ehime U.), N. Kawai, R. Adachi, M. Niwano, R. Hosokawa (Tokyo Tech),
S. Nakahira, Y. Sugawara, S. Ueno, H. Tomida, M. Ishikawa, M. Tominaga, T. Nagatsuka (JAXA),
Y. Ueda, S. Yamada, S. Ogawa, K. Setoguchi, T. Yoshitake, U. Goto (Kyoto U.),
H. Tsunemi (Osaka U.), M. Yamauchi, K. Kurogi, K. Miike (Miyazaki U.), T. Kawamuro (NAOJ),
K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU), M. Sugizaki (NAOC) 
report on behalf of the MAXI team:

The MAXI/GSC nova alert system triggered on a bright uncatalogued X-ray transient source 
at UT 09:03:26 on 2021 January 9.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (62.003 deg, 4.679 deg) = (04 08 00, +04 40 44) (J2000) 
with a statistical 90% C.L. elliptical error region 
with long and short radii of 0.28 deg and 0.25 deg, respectively. 
The roll angle of the long axis from the north direction is 58.0 deg counterclockwise. 
Without assumptions on the source flux constancy, we obtain a rectangular error box
for the transient source with the following corners:
(60.844, 3.548) deg = (04 03 22, +03 32 52) (J2000) 
(61.261, 3.251) deg = (04 05 02, +03 15 03) (J2000) 
(62.919, 5.559) deg = (04 11 40, +05 33 32) (J2000) 
(62.501, 5.857) deg = (04 10 00, +05 51 25) (J2000) 
There is an additional systematic uncertainty of 0.1 deg (90% containment radius).

The X-ray flux averaged over the scan was 108 +- 23 mCrab
(4.0-10.0keV, 1 sigma error).
There was no significant excess flux in the previous transit at UT 07:30
and in the next transit at 10:36 with an upper limit of 20 mCrab for each.


GRB_name: GRB210104A
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29283
SUBJECT: GRB 210104A: Assy continued optical observations, correction to GCN circ. 29265
DATE:    21/01/10 16:05:11 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

V. Kim (FAI, Pulkovo Observatory), S. Belkin (IKI), A. Pozanenko (IKI), 
  M. Krugov (FAI),  Y. Aimuratov (FAI) report on behalf of GRB IKI FuN:

We continued observations of the GRB 210104A (Fermi GBM team, GCN 29232; 
Troja et al., GCN  29233; Frederiks et al., GCN  29258; Cherry et al., 
GCN 29268) with AZT-20 telescope of Assy-Turgen observatory starting on 
  Jan. 05 (UT) 12:55:33 in r'-filter.  We detect the optical afterglow 
(Troja et al., GCN 29233; Xin et al., GCN 29235; Hu et al., GCN 29236; 
Hosokawa et al., GCN  29237; Kim et al., GCN 29238, 29265; Lipunov et 
al., GCN 29239; Horiuchi et al., GCN 29241; Breeveld et al., GCN 29247; 
Zhu et al., GCN 29252; Paek  et al., GCN 29254; Kumar et al., GCN 29257; 
Smartt et al., GCN 29262; Romanov, GCN 29269; Anandagoda et al., GCN 
29273; Gokuldass, GCN 29274; Mao et al.,  GCN 29275; Moskvitin et al., 
GCN 29277).

Preliminary photometry is following

Date       UT start     Filter  Exp.   OT(AB)  Err. UL(3 sigma)
                                 (s)

2021-01-06 15:18:17     r'     82*60   22.00   0.08 23.0
2021-01-09 17:22:22     r'    136*60   22.88   0.19 24.1


The photometry is based on nearby stars of PanSTARRS-PS1.
Observations are continuing.

We also report corrected date of observation reported in the GCN 29265. 
The correct table of the GCN 29265 should be as follows

Date       UT start     Filter  Exp.   OT(AB)  Err.
2021-01-05 15:35:27     r'      20*60   20.85 0.07
2021-01-05 16:20:20     r'      20*60   21.23 0.10
2021-01-05 17:05:11     r'      20*60   21.19 0.06


GRB_name: GRB210110A
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29284
SUBJECT: GRB 210110A: MAXI/GSC detection
DATE:    21/01/10 17:00:16 GMT
FROM:    Motoko Serino at RIKEN/MAXI  <motoko@crab.riken.jp>

S. Yamada (Kyoto U.), H. Negoro (Nihon U.), M. Serino (AGU),
M. Nakajima, M. Aoki, K. Kobayashi, R. Takagi, K, Asakura, K, Seino (Nihon U.),
T. Mihara, T. Tamagawa, M. Matsuoka (RIKEN),
T. Sakamoto, S. Sugita, H. Nishida, K. Komachi, A. Yoshida (AGU),
Y. Tsuboi, W. Iwakiri, R. Sasaki, H. Kawai, Y. Okamoto, S. Kitakoga (Chuo U.),
M. Shidatsu (Ehime U.), N. Kawai, R. Adachi, M. Niwano, R. Hosokawa (Tokyo Tech),
S. Nakahira, Y. Sugawara, S. Ueno, H. Tomida, M. Ishikawa, M. Tominaga, T. Nagatsuka (JAXA),
Y. Ueda, S. Ogawa, K. Setoguchi, T. Yoshitake, U. Goto, R. Uematsu (Kyoto U.),
H. Tsunemi (Osaka U.), M. Yamauchi, K. Kurogi, K. Miike (Miyazaki U.), 
T. Kawamuro (NAOJ),
K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU), M. Sugizaki (NAOC)
report on behalf of the MAXI team:

The MAXI/GSC nova alert system triggered a bright uncatalogued X-ray 
transient source at UT 15:14:40 on 2021 January 10.
Assuming that the source flux was constant over the transit,
we obtain the source position at
(R.A., Dec) = (172.727 deg, -41.315 deg) = (11 30 54, -41 18 52) (J2000)
with a 90% C.L. statistical error of 0.30 deg and an additional 
systematic uncertainty of 0.1 deg (90% containment radius).
The X-ray flux averaged over the scan was 127 +- 25 mCrab
(4.0-10.0keV, 1 sigma error).
There was no significant excess flux in the previous transit at 13:41 UT
and in the next transit at 16:47 with an upper limit of 20 mCrab for each.


GRB_name: GRB210104A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29286
SUBJECT: GRB 210104A: Mondy optical observations, light curve
DATE:    21/01/10 22:34:47 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

S. Belkin (IKI), A. Pozanenko (IKI),  E. Klunko (ISTP), V. Kim (FAI, 
Pulkovo Observatory), Y. Aimuratov (FAI), M. Krugov (FAI) report on 
behalf of GRB IKI FuN:

We observed  GRB 210104A (Fermi GBM team, GCN 29232; Troja et al., GCN 
29233; Frederiks et al., GCN  29258; Cherry et al., GCN 29268) with 
AZT-33IK telescope of Sayan observatory (Mondy).   We detect the optical 
afterglow (Troja et al., GCN 29233; Xin et al., GCN 29235; Hu et al., 
GCN 29236; Hosokawa et al., GCN  29237; Kim et al., GCN 29238, 29265; 
Lipunov et al., GCN 29239; Horiuchi et al., GCN 29241; Breeveld et al., 
GCN 29247; Zhu et al., GCN 29252; Paek  et al., GCN 29254; Kumar et al., 
GCN 29257; Smartt et al., GCN 29262; Romanov, GCN 29269; Anandagoda et 
al., GCN 29273; Gokuldass, GCN 29274; Mao et al.,  GCN 29275; Moskvitin 
et al., GCN 29277).

Preliminary photometry of the afterglow  is following

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

2021-01-07 15:10:23   3.19681  R      80*90   n/d     n/d 22.1
2021-01-08 15:22:18   4.20438  R      59*120  22.2    0.2 22.9
2021-01-09 11:51:54   5.07980  R      90*120  22.7    0.3 22.7


The photometry is based on nearby stars of  USNO-B1.0
USNO-B1.0_id R2
1546-0139059 15.53
1546-0139029 14.82

A light curve of the afterglow based on our observations including 
reported early (Kim et al., GCN 29238, 29265, 29283) can be found in

http://grb.rssi.ru/GRB210104A/GRB210104A_LC.png


GRB_name: GRB210112A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29289
SUBJECT: GRB 210112A: Swift detection of a burst with an optical counterpart
DATE:    21/01/12 01:51:00 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

E. Ambrosi (INAF-IASFPA), S. D. Barthelmy (GSFC),
A. D'Ai (INAF-IASFPA), V. D'Elia (SSDC), J. A. Kennea (PSU),
N. J. Klingler (PSU), S. Laha (GSFC/UMBC/CRESST),
A. Y. Lien (GSFC/UMBC), F. E. Marshall (NASA/GSFC),
D. M. Palmer (LANL) and M. H. Siegel (PSU) report on behalf of the
Neil Gehrels Swift Observatory Team:

At 01:37:03 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210112A (trigger=1016881).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 218.999, +33.070 which is 
   RA(J2000)  =  14h 36m 00s
   Dec(J2000) = +33d 04' 13"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows multiple peaks
with the larger peak at T+70 sec and duration of ~150 sec. The peak count rate
was ~20800 counts/sec (15-350 keV), at ~68 sec after the trigger. 

The XRT began observing the field at 01:38:18.0 UT, 74.2 seconds after
the BAT trigger. XRT found a bright, uncatalogued X-ray source located
at RA, Dec 219.0044, 33.0566 which is equivalent to:
   RA(J2000)  = 14h 36m 1.06s
   Dec(J2000) = +33d 03' 23.8"
with an uncertainty of 5.0 arcseconds (radius, 90% containment). This
location is 50 arcseconds from the BAT onboard position, within the BAT
error circle. No event data are yet available to determine the column
density using X-ray spectroscopy. 

The initial flux in the 0.1 s image was 7.10e-08 erg cm^-2 s^-1 (0.2-10
keV). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 82 seconds after the BAT trigger. There is a candidate afterglow in
the rapidly available 2.7'x2.7' sub-image at
  RA(J2000)  = 14:36:01.45 = 219.00606
  DEC(J2000) = +33:03:15.4  =  33.05428
with a 90%-confidence error radius of about 0.66 arc sec. This position is 9.8
arc sec. from the center of the XRT error circle. The estimated magnitude is
19.52 with a 1-sigma error of about  0.16. No correction has been made for the
expected extinction corresponding to E(B-V) of 0.014. 

Burst Advocate for this burst is E. Ambrosi (elena.ambrosi AT inaf.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: GRB210112A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29290
SUBJECT: GRB 210112A: Enhanced Swift-XRT position
DATE:    21/01/12 04:17:47 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 579 s of XRT Photon Counting mode data and 1 UVOT
images for GRB 210112A, 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 = 219.00603, +33.05415 which is equivalent
to:

RA (J2000): 14h 36m 1.45s
Dec (J2000): +33d 03' 15.0"

with an uncertainty of 1.7 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: GRB210104A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29291
SUBJECT: GRB 210104A: AROMA-N Optical Afterglow Detection
DATE:    21/01/12 06:36:42 GMT
FROM:    Takanori Sakamoto at AGU  <tsakamoto@phys.aoyama.ac.jp>

M. Nakamura, K. Hasuda, T. Sakamoto (AGU)

We observed the field of GRB 210104A (Troja et al., GCN Circ. 29233;
Malacaria et al., GCN Circ. 29246; Frederiks et al., GCN Circ. 29258;
Cherry et al., GCN Circ. 29268) with the 14-inch AGU Robotic Optical
Monitor for Astrophysical object - Narrow (AROMA-N) located at
the Sagamihara campus of Aoyama Gakuin University.

60 images of 60 sec exposures were taken in the R filter starting
from January 4 11:29:50 (UT) about 171 seconds after the trigger and
stopped on January 4 12:45:20 (UT).  We detected the optical afterglow
at the consistent position previously reported (Troja et al., GCN Circ. 29233;
Xin et al., GCN Circ. 29235; Hu et al., GCN Circ. 29236; Hosokawa et al.,
GCN Circ. 29237; Kim et al., GCN Circ. 29238, 29265; Lipunov et al.,
GCN Circ. 29239; Horiuchi et al., GCN Circ. 29241; Breeveld et al.,
GCN Circ. 29247; Zhu et al., GCN Circ. 29252; Paek et al., GCN Circ. 29254;
Kumar et al., GCN Circ. 29257; Smartt et al., GCN Circ. 29262; Romanov,
GCN Circ. 29269; Anandagoda et al., GCN Circ. 29273; Gokuldass, GCN Circ. 29274;
Mao et al., GCN Circ. 29275; Moskvitin et al., GCN Circ. 29277;
Belkin et al., GCN Circ. 29286).  The clear decay signature was visible in our
images.  The magnitudes of the initial 60 s image and the combined
image from T+2915 sec to T+3577 sec images (total exposure of 540 sec)
were 14.3 mag and 17.1 mag.  The afterglow light curve of our data showed
the initial temporal decay of -1.4 following by the shallow decay of -0.6
at the break around T+650 sec.  Our reported magnitudes are calibrated using
the USNO-B1 catalog.


GRB_name: GRB210112A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29292
SUBJECT: GRB 210112A: Kitab a optical upper limit
DATE:    21/01/12 11:19:27 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

A. Novichonok (Petrozavodsk State University, KIAM), S. Belkin (IKI), 
A. Pozanenko (IKI), Sh. Ehgamberdiev (UBAI) report on behalf of GRB IKI FuN:

We observed the field of GRB 210112A (Ambrosi  et al., GCN 29289) with 
  Kitab-ISON RC-36  telescope starting on 2021-01-12 (UT) 01:54:30, i.e. 
447 seconds after trigger in Clear filter. We do not detect the 
afterglow candidate (Ambrosi  et al., GCN 29289) within enhanced 
Swift-XRT position (Goad et al., GCN 29290).
Preliminary photometry of the field is following

Date,      UT start, t-T0,   Exp.,  Filter,  OT,   Err., UL
                     (mid, days)
2021-01-12  01:54:30  0.01541 11*30 CR       n/d   n/d   18.5


The photometry is based on nearby USNO-B1.0 stars
USNO-B1.0_id R2
1231-0260671 14:35:00.70080 +33:06:09.4428 14.32
1229-0281658 14:34:57.67344 +32:58:13.0800 14.75



At 01:37:03 UT


GRB_name: GRB210112A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29293
SUBJECT: GRB 210112A: AGILE detection
DATE:    21/01/12 12:30:09 GMT
FROM:    Alessandro Ursi at INAF/IAPS  <alessandro.ursi@gmail.com>

A. Ursi, M. Cardillo (INAF/IAPS), C. Pittori (SSDC, and INAF/OAR), M.
Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Argan, C. Casentini, Y.
Evangelista, G. Piano (INAF/IAPS), F. Lucarelli, F. Verrecchia (SSDC, and
INAF/OAR), A. Bulgarelli, 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 GRB 210112A, reported by Swift (GCNs #29289,
#29290), at T0 = 2021-01-12 01:37:58 (UT).

The event is clearly visible in the scientific ratemeters of the SuperAGILE
(SA; 18-60 keV), MiniCALorimeter (MCAL; 0.4-100 MeV), and AntiCoincidence
(AC; 50-200 keV) detectors. The burst lasted about 25 s and released 1120
counts in the SA detector (above a background rate of 60 Hz), 25140 counts
in the MCAL detector (above a background rate of 1250 Hz), and 71500 counts
in the AC detector (above a background rate of 3570 Hz). The AGILE
ratemeters light curves can be found at:
http://www.agilescienceapp.it/notices/GRB210112A_AGILE_RM.png .

Additional analysis of AGILE data is in progress.


GRB_name: GRB210112A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29295
SUBJECT: GRB 210112A: Swift-XRT refined Analysis
DATE:    21/01/12 17:20:18 GMT
FROM:    Phil Evans at U of Leicester  <pae9@leicester.ac.uk>

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

We have analysed 8.5 ks of XRT data for GRB 210112A (Ambrosi et al. GCN
Circ. 29289), from 77 s to 46.0 ks after the  BAT trigger. The data
comprise 859 s in Windowed Timing (WT) mode with the remainder in
Photon Counting (PC) mode. The enhanced XRT position for this burst was
given by Goad et al. (GCN Circ. 29290).

The late-time light curve (from T0+6.4 ks) can be modelled with a
power-law decay with a decay index of alpha=1.36 (+/-0.06).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.56 (+/-0.03). The
best-fitting absorption column is  2.34 (+/-0.14) x 10^21 cm^-2, in
excess of the Galactic value of 9.5 x 10^19 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.01 (+0.10, -0.09)
and a best-fitting absorption column of 2.8 (+/-0.4) 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 (5.1 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      2.8 (+/-0.4) x 10^21 cm^-2
Galactic foreground: 9.5 x 10^19 cm^-2
Excess significance: 12.3 sigma
Photon index:      2.01 (+0.10, -0.09)

If the light curve continues to decay with a power-law decay index of
1.36, the count rate at T+24 hours will be 0.046 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.7 x
10^-12 (2.3 x 10^-12) erg cm^-2 s^-1.

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01016881.

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


GRB_name: GRB210112A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29296
SUBJECT: GRB 210112A: OSN Reddened Afterglow Detection
DATE:    21/01/12 19:28:59 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. C. Thoene (HETH), M. Blazek, J. F. Agui Fernandez (both 
HETH/IAA-CSIC), and A. Sota (IAA-CSIC) report:

We observed the optical afterglow of GRB 210112A (Swfit detection: 
Ambrosi et al., GCN #29289; AGILE Detection: Ursi et al., GCN #29293) 
with the 1.5m telescope of the Observatorio de Sierra Nevada (OSN), 
Granada, Spain. We obtained 12 x 90 s exposures in B, Rc, Ic and 11 x 90 
s in V, between 2021-01-12 04:03:22.52 and 2021-01-12 05:21:34.99 UT. 
The afterglow is detected In the combined image of each band.

At 0.12587 days after the GRB, we measure Rc = 22.41 +/- 0.12 mag (AB 
mag, vs. a several nearby SDSS stars converted to Rc following the 
Lupton transformations, then transformed back to AB mag).

A preliminary analysis of all data reveals peculiar colors, the Rc - Ic 
color is large, whereas the colors between B, V, and Rc are quite flat. 
There is no source detected in either SDSS or PanSTARRS at the afterglow 
position, so this is probably not due to influence of the host galaxy. 
However, we are able to fit this SED with a large (A_V > 1 mag) amount 
of Milky-Way like dust at a redshift of z ~ 2 and an intrinsic slope in 
agreement with the one derived from X-ray observations. Such high 
extinction would be in line with the significant excess column density 
seen in the XRT observations (Evans et al., GCN #29295).


GRB_name: GRB210112A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29297
SUBJECT: GRB 210112A: Swift-BAT refined analysis
DATE:    21/01/13 01:45:13 GMT
FROM:    Amy Lien at GSFC  <amy.y.lien@nasa.gov>

M. Stamatikos (OSU), E. Ambrosi (INAF-IASFPA),
S. D. Barthelmy (GSFC), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL),
T. Sakamoto (AGU), T. N. Ukwatta (LANL)
(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 210112A (trigger #1016881)
(Ambrosi et al., GCN Circ. 29289).  The BAT ground-calculated position is
RA, Dec = 219.005, 33.058 deg which is
   RA(J2000)  =  14h 36m 01.3s
   Dec(J2000) = +33d 03' 30.4"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 89%.

The mask-weighted light curve shows a multi-peaked structure that starts
at ~T-10 s and ends at ~T+220 s. The three main peaks occur at ~T+1 s,
~T+70 s, and ~T+105 s, respectively, and the one at ~T+70 s is the largest
peak.
T90 (15-350 keV) is 107.60 +- 13.02 sec (estimated error including
systematics).

The time-averaged spectrum from T-10.44 to T+218.47 sec is best fit by
a simple power-law model.  The power law index of the time-averaged
spectrum  is 1.45 +- 0.03.  The fluence in the 15-150 keV band is
2.33 +- 0.03 x 10^-5 erg/cm2. The 1-sec peak photon flux measured from
T+68.86 sec in the 15-150 keV band is 20.5 +- 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/1016881/BA/


GRB_name: GRB210104A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29299
SUBJECT: GRB 210104A: AstroSat CZTI detection
DATE:    21/01/13 18:24:27 GMT
FROM:    Gaurav Waratkar at IIT Bombay  <gauravwaratkar24@gmail.com>

D. Nadella (NITK), G. Waratkar (IITB), A. Vibhute (IUCAA), S. Gupta
(IUCAA), P. Sawant (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 bright long GRB 210104A, which was
also detected by Fermi-GBM (GCN #29232), Swift-BAT (GCN #29233), Konus-Wind
(GCN #29258) and CALET-CGBM (GCN #29268).

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
2021-01-04 11:27:17.5 UT. The measured peak count rate associated with the
burst is 867 (+60, -56) cts/s above the background in the combined data of
four quadrants, with a total of 7003 (+407, -394) cts. The local mean
background count rate was 555 (+2, -2) cts/s. Using cumulative rates, we
measure a T90 of  33 (+7, -1) 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 2021-01-04 11:27:17 UT. The measured
peak count rate is 606 (+86, -55) cts/s above the background in the
combined Veto data of four quadrants, with a total of 4520 (+693, -789)
cts. The local mean background count rate was 2009 (+4, -5) cts/s. We
measure a T90 of 35 (+7, -14) 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: GRB210112A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29300
SUBJECT: GRB 210112A: OSN second epoch, decay
DATE:    21/01/13 19:50:01 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. C. Thoene (HETH), M. Blazek, J. F. Agui Fernandez (both 
HETH/IAA-CSIC), and A. Sota (IAA-CSIC) report:

We observed again the optical afterglow of GRB 210112A (Swfit detection: 
Ambrosi et al., GCN #29289; AGILE Detection: Ursi et al., GCN #29293) 
with the 1.5m telescope of the Observatorio de Sierra Nevada (OSN), 
Granada, Spain. We obtained 3 x 450 s exposures in B, V, Rc each, and 8 
x 150 s in Ic, between 2021-01-13 04:29:28.99 and 2021-01-13 05:55:34.35 
UT.  The afterglow is now only detected in the combined Ic-band image. 
Together with the observations of the day before (Kann et al., GCN 
#29296), we measure (against the same SDSS comparison stars as before, 
in Vega mags):

Ic = 20.65 +/- 0.075 mag at 0.12587 days.

Ic = 22.57 +/- 0.217 mag at 1.12739 days.

This implies a decay index of alpha ~ 0.8.


GRB_name: GRB210112A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29301
SUBJECT: GRB 210112A: 1.3m DFOT Optical upper limit
DATE:    21/01/13 19:54:17 GMT
FROM:    Rahul Gupta at ARIES, India  <rahulbhu.c157@gmail.com>

Rahul Gupta (ARIES),  Amit Kumar (ARIES), Dimple (ARIES), Ankur Ghosh
(ARIES), Krishan Chand (ARIES), Amar Aryan (ARIES), Shashi B. Pandey
(ARIES), and Kuntal Misra (ARIES) report:


We observed the filed of Swift and AGILE detected GRB 210112A (Ambrosi
et al., GCN 29289; and Ursi et al., GCN 29293) 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 2021-01-13 at 00:06:18 UT i.e.
~ 22.49 hours after the BAT trigger. We have taken multiple frames
having an exposure time of 120 s in the R filter. We do not detect the
optical afterglow candidate (Ambrosi et al., GCN 29289; and Kann et
al., GCN 29296) within enhanced Swift-XRT position (Goad et al., GCN
29290).


We obtain the following 3-sigma upper limits in the stacked image.


Date Start_UT    T_start-T0 (hrs)        Filter   Exp time (s)
Limiting Magnitude

============================================================
2021-01-13   00:18:18      22.69              R              120*12
           > 22.0



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 catalogue.

This circular may be cited.


GRB_name: GRB210112A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29302
SUBJECT: GRB 210112A: Mondy optical observations
DATE:    21/01/13 20:28:18 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We observed the field of GRB 210112A (Ambrosi  et al., GCN 29289; Ursi 
et al., GCN #9293) with AZT-33IK telescope of Sayan observatory (Mondy) 
starting on 2021-01-12 (UT) 20:41:40. The optical afterglow (Ambrosi  et 
al., GCN 29289; Kann  et al., GCNs 29296, 29300) is not detected in 
stacked  image in R-filter. The non detection of the afterlow is 
consistent with other non-detections in R-filter (Novichonok  et al., 
GCN 29292; Gupta et al., GCN 29301).

Preliminary photometry of the optical transient in a combined image is 
following

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

2021-01-12 20:41:40   0.80738    R      18*120   n/d  n/d   22.4


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


GRB_name: GRB210112A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29303
SUBJECT: GRB 210112A: Swift/UVOT Detection
DATE:    21/01/15 03:50:43 GMT
FROM:    Mike Siegel at PSU/Swift MOC  <mhs18@psu.edu>

M. H. Siegel (PSU) and Ambrosi (INAF-IASFPA)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 210112A
83 s after the BAT trigger (Ambrosi et al., GCN Circ. 29289).
A source consistent with the XRT position
(Goad et al. GCN Circ. 29290)
is detected in the initial UVOT exposures.

The preliminary UVOT position is:
  RA  (J2000) =  14:36:01.49 = 219.00619 (deg.)
  Dec (J2000) = +33:03:15.3  =  33.05424 (deg.)
with an estimated uncertainty of 0.50 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               83          233          147         19.54 +/- 0.10
v                  626         1419           97        >18.5
b                  551         1517           97        >19.1
u                  296         1493          304        >20.2
w1                 675         1468           78        >19.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.014 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB210104A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29304
SUBJECT: GRB 210104A: JCMT SCUBA-2 sub-mm observations
DATE:    21/01/15 21:55:33 GMT
FROM:    Ian Smith at Rice U  <ian.smith.astronomy@gmail.com>

I.A. Smith (Rice U.), D.A. Perley (LJMU), and N.R. Tanvir 
(U. of Leicester) report:

We observed the Swift UVOT location of GRB 210104A (Troja 
et al., GCN Circ. 29233) using the SCUBA-2 sub-millimeter 
continuum camera on the James Clerk Maxwell Telescope.  The 
observation started at 08:23 UT on 2021-01-05, with the 
mid-point of the run at 0.894 days after the burst trigger.  
Exposures totaling 1.0 hours were made in very good weather 
conditions.  No source was detected, with the RMS background 
noise being 1.7 mJy/beam at 850 microns and 14.5 mJy/beam 
at 450 microns.

We thank Kevin Silva, Mark Rawlings, and the JCMT staff for 
the prompt support of these observations that were taken under 
project M20BP026.


GRB_name: GRB201015A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29306
SUBJECT: GRB 201015A: evidence of supernova in LBT spectra
DATE:    21/01/17 02:05:04 GMT
FROM:    Andrea Rossi at INAF  <andrea.rossi@inaf.it>

A. Rossi (INAF/OAS), S. Benetti (INAF-Padova), E. Palazzi (INAF/OAS), P. 
D'Avanzo (INAF-OAB), V. D'Elia (SSDC), and M. De Pasquale report on 
behalf of the CIBO collaboration:

We report the results of the photometric and spectroscopic follow-up of 
GRB 201015A (D'Elia et al. GCN 28632) at z = 0.42 (Izzo et al. GCN 
28661, de Ugarte Postigo et al. GCN 28649) obtained with the 
Multi-Object Double Spectrographs (MODS) instrument mounted on the 
2x8.4-m LBT telescope (Mt Graham, AZ, USA). Data were obtained at the 
mid time of 04:00 UT on 2020-11-13, ~28.8 days after the burst trigger.

Spectroscopy of the source was obtained for a total of 8x900 s, covering 
the wavelength range 3200-10000 AA. All the spectra have been corrected 
for the Galactic extinction (A_V = 0.93). The low S/N spectrum shows a 
peak around 5400 AA (rest frame) and is consistent with type Ic-BL 
supernova spectra around maximum light, in agreement with the results 
presented by Pozanenko et al. (GCN 29033).

Together with the spectroscopy we also obtained g and r-band imaging of 
the supernova, which thanks to the good seeing of 0.6" it is separated 
enough from the host galaxy to avoid contamination. We find r=23.5+-0.1 
for the SN and r=22.9+-0.2 for the host galaxy, calibrated against 
Pan-STARRS field stars.

We acknowledge the excellent support from the LBTO in particular D. 
Thompson, and from the LBT-INAF staff, particularly S. Paiano, F. 
Cusano, D. Paris and L. CassarÃ  in obtaining and reducing these 
observations.


GRB_name: GRB201221D
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29311
SUBJECT: GRB 201221D: near-infrared observation with LBT
DATE:    21/01/17 15:18:45 GMT
FROM:    Andrea Rossi at INAF  <andrea.rossi@inaf.it>

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

We observed the location of the optical afterglow (Malesani et al., GCN 
29117) of the short GRB 201221D (Page et al., GCN 29112) simultaneously 
in the J and Ks bands with the LUCI near-infrared imager and 
spectrograph mounted on the Large Binocular Telescope (LBT, Mt Graham, 
AZ, USA). Observations were obtained on 2020-12-24 at the UT midtime 
11:40:00, i.e. ~2.5 days after the burst trigger, for a total of 20 min 
of exposure in each band.

Inspection of the combined J and K-band images reveals a faint, extended 
source in both filters, for which we preliminary measure J=21.7+-0.3 
(Vega system), calibrated against 2MASS field stars.

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


GRB_name: GRB210112A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29315
SUBJECT: Konus-Wind detection of GRB 210112A
DATE:    21/01/17 23:28:52 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

The long-duration GRB 210112A
(Swift-BAT detection: Ambrosi et al., GCN Circ. 29289;
AGILE detection: Ursi et al., GCN Circ. 29293)
triggered Konus-Wind at T0=5886.553 s UT (01:38:06.553).

The burst light curve shows a multipeaked structure
which starts at ~T0-73 s and has a total duration of ~143 s.
The emission is seen up to ~5 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB210112_T05886

As observed by Konus-Wind, the burst
had a fluence of 6.72(-0.65,+0.72)x10^-5 erg/cm2,
and a 64-ms peak flux, measured from T0+7.856 s,
of 1.02(-0.18,+0.19)x10^-5 erg/cm2/s
(both in the 20 keV - 16 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+68.608 s)
is best fit in the 20 keV - 16 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.96(-0.08,+0.08),
the high energy photon index beta = -2.71(-0.53,+0.25),
the peak energy Ep = 214(-16,+18) keV
(chi2 = 87/97 dof).

The spectrum near the maximum count rate
(measured from T0+7.168 s to T0+9.216 s)
is best fit in the 20 keV - 16 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.85(-0.12,+0.13),
the high energy photon index beta = -2.67(-0.57,+0.27),
the peak energy Ep = 219(-25,+28) keV
(chi2 = 38/65 dof).

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB210104A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29318
SUBJECT: GRB 210104A: Late-time CAHA 2.2m detection
DATE:    21/01/18 15:51:26 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. C. Thoene (HETH), M. Blazek, J. F. Agui 
Fernandez (both HETH/IAA-CSIC), and J. I. Vico Linares (CAHA) report:

We observed the afterglow position (Troja et al., GCN #29233) of the 
bright Swift/Fermi GRB 210104A (Swift detection: Troja et al., GCN 
#29233; GBM detection: Fermi GBM Team, GCN #29232; Biltzinger et al., 
GCN #29234; Konus-Wind detection: Frederiks et al., GCN #29258; CALET 
detection: Cherry et al., GCN #29268; AstroSat CZTI detection: Nadella 
et al., GCN #29299) with CAFOS at the 2.2m telescope at Calar Alto, 
Almeria, Spain, in the Rc band. We obtained 6 x 600 s exposures, 
centered at 11.4624 days after the GRB, under good conditions but 
mediocre seeing.

After removing the halo of a nearby star, the afterglow (Xin et al., GCN 
#29235; Hu et al., GCN #29236; Hosokawa et al., GCN #29237; Kim et al., 
GCNs #29238,29265,29283; Horiuchi et al., GCN #29241; Breeveld et al., 
GCN #29247; Lipunov et al., GCN #29248; Zhu et al., GCN #29252; Paek et 
al., GCN #29254; Kumar et al., GCN #29257; Smartt et al., GCN #29262; 
Anandagoda et al., GCN #29273; Gokuldass et al., GCN #29274; Mao et al., 
GCN #29275; Moskvitin et al., GCN #29277; Belkin et al., GCN #29286; 
Nakamura et al., GCN #292291) is faintly but clearly detected.

Against three SDSS comparison stars (transformed to Rc band using the 
Lupton 2005 equations, then transformed back to AB magnitude), we 
measure Rc = 23.67 +/- 0.14 mag. This value is in agreement with the 
extrapolation of the light curve decay reported by Belkin et al., GCN 
#29286 (A. Pozanenko, priv. comm.). This implies there is no significant 
evidence for a supernova rise, and therefore the redshift of GRB 210104A 
is conservatively estimated to be z > 0.4 (e.g., SN 2012eb associated 
with GRB 120714B at z ~ 0.4 peaks at r' ~ 22.2 mag 12 days after 
trigger, Klose et al. 2019, A&A, 622, A138).

We thank Alexei Pozanenko for discussions.


GRB_name: GRB210112A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29319
SUBJECT: GRB 210112A: Deep CAHA 2.2m detection
DATE:    21/01/18 15:53:55 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. C. Thoene (HETH), M. Blazek, J. F. Agui Fernandez (both 
HETH/IAA-CSIC), and J. I. Vico Linares (CAHA) report:

We observed the afterglow position (Ambrosi et al., GCN #29289) of the 
bright Swift GRB 210112A (Swift detection: Ambrosi et al., GCN #29289; 
AGILE detection: Ursi et al., GCN #29293; Konus-Wind detection: Svinkin 
et al., GCN #29315) with CAFOS at the 2.2m telescope at Calar Alto, 
Almeria, Spain, in the Ic band. We obtained 10 x 360 s exposures, 
centered at 5.1696 days after the GRB, under good conditions but 
mediocre seeing.

The afterglow (Kann et al., GCNs #29296,29300; Siegel et al., GCN 
#29303) is faintly detected. We measure Ic = 23.69 +/- 0.24 mag. (AB 
mag, vs. a several nearby SDSS stars converted to Ic following the 
Lupton transformations, then transformed back to AB mag).

This magnitude lies slightly above the extrapolation of the decay found 
during the first two epochs (Kann et al., GCN #29300) and may indicate 
an underlying host galaxy. Indeed we also see another faint, possibly 
extended source about 2" to the East, at RA (J2000) = 14:36:01.453, Dec. 
(J2000) = +33:03:13.40, which may be the host galaxy or a system 
interacting with it. However, the rough redshift estimate of z ~ 2 (Kann 
et al., GCN #29296) would imply this must be a very luminous system, or 
a foreground interloper.


GRB_name: GRB200613A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29320
SUBJECT: GRB 200613A: Host galaxy redshift from OSIRIS/GTC
DATE:    21/01/18 17:29:38 GMT
FROM:    Antonio de Ugarte Postigo at IAA-CSIC  <deugarte@iaa.es>

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

We obtained spectroscopy of the host galaxy of GRB 200613A (Fermi-LAT 
detection: Ohno et al. GCN #27931; Fermi GBM detection: Bissaldi & Lesage, 
GCN #27930; optical counterpart discovery: Kann et al. GCN #27935) with OSIRIS, 
mounted on the 10.4m GTC telescope (Roque de los Muchachos Observatory, 
La Palma, Spain). The observation was performed on the 18 January 2021 with 
mean epoch at 00:02 UT (218.75 days after the burst) and consisted of 3x1200s 
exposures with grism R1000R, covering the range between 5100 and 10100 Ã…. 

The spectrum is characterised by a continuum that is detected over the complete 
spectral range, with better SNR in the blue part of the spectrum, and has a strong 
emission feature that we identify as the [OII] 3727/3729 doublet, at a redshift of 
1.2280. At a similar redshift of 1.2255 we also identify absorptions due to FeII and 
MgII, that allow us to confirm the redshift, which we identify as that of GRB 200613A.


GRB_name: GRB210119A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29322
SUBJECT: GRB 210119A: Fermi GBM Final Real-time Localization
DATE:    21/01/19 03:04:37 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 02:54:09 UT on 19 Jan 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210119A (trigger 632717654.819782 / 210119121).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 285.8, Dec = -63.1 (J2000 degrees, equivalent to J2000 19h 03m, -63d 06'), with a statistical uncertainty of 7.8 degrees.

The angle from the Fermi LAT boresight is 7.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210119121/quicklook/glg_skymap_all_bn210119121.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/bn210119121/quicklook/glg_healpix_all_bn210119121.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210119121/quicklook/glg_lc_medres34_bn210119121.gif


GRB_name: GRB210119A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29323
SUBJECT: Swift detection of a new SGR Swift J1851.2-6148 or a short GRB 210119A
DATE:    21/01/19 03:17:54 GMT
FROM:    David Palmer at LANL  <palmer@lanl.gov>

M. J. Moss (GWU), S. D. Barthelmy (GSFC), H. A. Krimm (NSF),
A. Y. Lien (GSFC/UMBC), K. L. Page (U Leicester) and
D. M. Palmer (LANL) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 02:54:09 UT, the Swift Burst Alert Telescope (BAT) triggered and
located a short burst which would be either an unknown Soft Gamma 
Repeater or GRB 210119A (trigger=1017711). 
The BAT on-board calculated location is 
RA, Dec 282.804, -61.801 which is 
   RA(J2000) = 18h 51m 13s
   Dec(J2000) = -61d 48' 02"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single peak
structure with a duration of 0.128 sec or less.  The peak count rate
was ~8000 counts/sec (15-350 keV), at ~0 sec after the trigger. 

Due to a Sun observing constraint, Swift cannot slew to the BAT
position until 12:54 UT on 2021 January 26. There will thus be no XRT
or UVOT data for this trigger before this time. 

Due to the short timescale of the peak and the location of the source
in the Galactic bulge (lat, lon = 333.99, -23.67) this event may be
from a previously unknown Soft Gamma Repeater, which we would name
SGR Swift J1851.2-6148 . 

Burst Advocate for this burst is M. J. Moss (mikejmoss3 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: GRB210119A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29324
SUBJECT: Fermi GRB 210119A: Global MASTER-Net observations report 
DATE:    21/01/19 03:30:33 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 210119A ( Fermi GBM team, GCN 29322) errorbox 45 sec after trigger time at 2021-01-19 02:54:54 UT, with upper limit up to  15.1 mag. Observations started at twilight.  The observations began at zenith distance = 65 deg. The sun  altitude  is -11.3 deg. 

MASTER-OAFA robotic telescope  located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 210119A errorbox  57 sec after notice time and 108 sec after trigger time at 2021-01-19 02:55:58 UT, with upper limit up to  12.2 mag. The observations began at zenith distance = 84 deg. The sun  altitude  is -32.3 deg. 

The galactic latitude b = -26 deg., longitude l = 333 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1529080

We obtain a following upper limits.  

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

      50 | 2021-01-19 02:54:54 |         MASTER-SAAO | (18h 32m 27.92s , -60d 49m 23.7s) | P\  |    10 | 15.1 |        
      79 | 2021-01-19 02:55:24 |         MASTER-SAAO | (18h 32m 30.98s , -60d 47m 57.6s) | P\  |    10 | 15.0 |        
     114 | 2021-01-19 02:55:53 |         MASTER-SAAO | (18h 32m 25.77s , -60d 48m 47.0s) | P\  |    20 | 15.1 |        
     119 | 2021-01-19 02:55:58 |         MASTER-OAFA | (19h 56m 18.53s , -62d 36m 50.8s) |   C |    20 | 12.3 |        
     158 | 2021-01-19 02:56:33 |         MASTER-SAAO | (18h 32m 25.96s , -60d 47m 45.1s) | P\  |    30 | 15.0 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB210119A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29325
SUBJECT: Short Fermi GRB 210119A or new SGR Swift J1851.2-6148: Possible MASTER Short OT detection 
DATE:    21/01/19 08:16:39 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

  N.Tiurina, V. Lipunov, V.Kornilov, E.Gorbovskoy, P.Balanutsa,F.Balakin, 
V.Vladimirov, A.Kuznetsov,K.Zhirkov,D. Vlasenko, I.Gorbunov, D.Zimnukhov, 
V.Senik, A.Chasovnikov,A.Pozdnyakov,V.Topolev, D.Cheryasov(Lomonosov 
Moscow State  University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico 
Felix Aguilar, San Huan National University),
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, Yu. Sergienko (Blagoveschensk Educational 
StateUniversity)

MASTER-OAFA robotic telescope  located in Argentina (OAFA observatory of 
San Juan National University) started inspect of the Fermi GRB 210119A 
errorbox  57 sec after notice time and 108 sec after trigger time at 
2021-01-19 02:55:58 UT (Lipunov et al., GCN #29324). MASTER autodetection 
system  found  short OT on one of unfiltered image.

    Date/Time UT             RA                Dec        Exp    mag 
2021-01-19 04:20:32  18h 51m 11.42s  -61d 48m 06s.3   180s  ~17

Error is ~1" .
The message may be cited.


GRB_name: GRB210112A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29326
SUBJECT: GRB 210112A: Insight-HXMT/HE detection
DATE:    21/01/19 11:22:13 GMT
FROM:    Y Q Zhang at IHEP  <yqzhang@ihep.ac.cn>

C. Zheng, C. Cai, J. C. Liu, Q. Luo, S. Xiao, 
W. C. Xue, Q. B. Yi, Y. Q. Zhang, Y. Huang, C. K. Li, 
G. Li, X. B. Li, J. Y. Liao, X. Y. Song, S. L. Xiong, C. Z. Liu, 
X. F. Li, Z. W. Li, Z. Chang, A. M. Zhang, Y. F. Zhang, 
X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), 
T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, 
M. Wu, Y. P. Xu, S. N. Zhang (IHEP), 
report on behalf of the Insight-HXMT team:

At 2021-01-12T01:38:13.400 (T0), Insight-HXMT/HE detected 
GRB 210112A (trigger ID: HEB210112068) in a routine search of the data, 
which also triggered Swift/BAT (E. Ambrosi (INAF-IASFPA) et al. ,GCN #29289).

The Insight-HXMT/HE light curve mainly consists of multiple 
pulses with a duration (T90) of 12.27 s measured from T0+0.91 s. 
The 1-ms peak rate, measured from T0+7.63 s, is 2134 cnts/sec. 
The total counts from this burst is 213416252 counts. 
URL_LC: http://twiki.ihep.ac.cn/pub/HXMT/GRBList/HEB210112068_lc.jpg

All measurements above are made with the CsI detectors operating in the 
regular mode with the energy range of about 80-800 keV (deposited energy). 
Only gamma-rays with energy greater than about 200 keV can penetrate 
the spacecraft and leave signals in the CsI detectors installed inside 
of the telescope. 

Insight-HXMT is the first Chinese space X-ray telescope, which was 
funded jointly by the China National Space Administration (CNSA) and 
the Chinese Academy of Sciences (CAS). 
More information about it could be found at: 
http://www.hxmt.org.


GRB_name: GRB210119A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29328
SUBJECT: GRB 210119A: Fermi GBM observation
DATE:    21/01/19 14:09:07 GMT
FROM:    Joe Mangan at UCD  <joseph.mangan@ucdconnect.ie>

J.Mangan (UCD), R.Dunwoody (UCD), S. Lesage (UAH), C. Meegan (UAH)
report on behalf of the Fermi GBM Team:


At 02:54:09.82 UT on 19 January 2021, the Fermi Gamma-Ray Burst
Monitor (GBM) triggered and located GRB 210119A (trigger 632717654 /
210119.121),
which was also detected by the Swift/BAT (M. J. Moss et al. 2021, GCN
29323). The Fermi GBM Final Real-time Localization (GCN 29322) is
consistent with the Swift position.


The angle from the Fermi LAT boresight at the GBM trigger time is 8 deg degrees.

The GBM light curve consists of a short bright burst
with a duration (T90) of about 0.05 s (50-300 keV).
The time-averaged spectrum from T0-0.064 s to T0+0.064 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -0.82 +/- 0.18 and
the cutoff energy, parameterized as Epeak, is 515 +/- 168 keV.
Unlikely to be an SGR given Epeak result. The event fluence (10-1000
keV) in this time interval is
(3.432 +/- 0.397)E-7 erg/cm^2. The 64-ms peak photon flux measured
starting from T0-0.064 s in the 10-1000 keV band
is 11.7 +/- 1.3 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.htmlFor Fermi
GBM data and info, please visit the official Fermi GBM Support Page:
https://fermi.gsfc.nasa.gov/ssc/data/access/gbm/"


GRB_name: GRB210119A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29329
SUBJECT: GRB 210119A: Insight-HXMT/HE detection
DATE:    21/01/19 15:33:21 GMT
FROM:    QiBin Yi at IHEP, HXMT  <yiqb@ihep.ac.cn>

Q. B. Yi, S. Xiao, Q. Luo, C. Cai, C. K. Li, X. B. Li, G. Li, J. Y. Liao, S. L. Xiong, C. Z. Liu, X. F. Li, Z. W. Li, Z. Chang, X. F. Lu, A. M. Zhang, Y. F. Zhang, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, M. Wu, Y. P. Xu, S. N. Zhang (IHEP), report on behalf of the Insight-HXMT team: At 2021-01-19T02:54:09.82 (T0), Insight-HXMT/HE detected GRB 210119A (trigger ID: HEB210119120) in a routine search of the data, which was also triggered by Fermi/GBM (GCN #29322) and Swift/BAT (M. J. Moss. et al., GCN #29323). The Insight-HXMT/HE light curve mainly consists of a single   pulse with a duration (T90) of 0.03 s measured from T0+0.01 s. The 1-ms peak rate, measured from T0+0.004 s, is 4418 cnts/sec. The total counts from this burst is 62 counts. URL_LC: http://twiki.ihep.ac.cn/pub/HXMT/GRBList/HEB210119120_lc.jpg All measurements above are made with the CsI detectors operating in the regular mode with the energy range of about 80-800 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope. Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://www.hxmt.org.


GRB_name: GRB210119A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29331
SUBJECT: GECAM detection of a short GRB 210119A or a new SGR candidate Swift J1851.2-6148
DATE:    21/01/19 17:31:21 GMT
FROM:    Shaolin Xiong at IHEP  <xiongsl@ihep.ac.cn>

Z. H. An, C. Cai, G. Chen, W. Chen, M. Gao, M. Y. Ge, K. Gong, D. Y. Guo,
J. J. He, Y. Huang, B. Li, C. Li, C. Y. Li, J. H. Li, M. S. Li, L. X. Li,
X. B. Li, X. Q. Li, Y. G. Li, X. H. Liang, J.C. Liu, X. J. Liu, Y. Q. Liu,
F. J. Lu, Q. Luo, X. Ma, G. Ou, W. X. Peng, R. Qiao, J. Y. Shi, D. L. Shi,
L. M. Song, X. Y. Song, G. X. Sun, X. L. Sun, Y. L. Tuo, J. Z. Wang,
C. W. Wang, P. Wang, W. S. Wang, X. Y. Wen, S. Xiao, S. L. Xiong, Y. B. Xu,
Y. P. Xu, W. C. Xue, S. Yang, M. Yao, Q. B. Yi, K. Zhang, P. Zhang,
D. L. Zhang, F. Zhang, H. M. Zhang, S. N. Zhang, Y. Q. Zhang, Z. Zhang,
S. Y. Zhao, X. Y. Zhao, Y. Zhao, C. Zheng, S. J. Zheng (IHEP), L. Chang,
Y. M. Chen, X. B. Han, J. Huang, J. P. Yu, K. K. Zhang (IAMCAS), L. Chen,
H. Geng, T. Hu, T. Jing, B. Q. Li, F. L. Ma, X. Meng, H. Y. Wu, J. Wu,
Z. G. Xiao, W. Zhang, Z. M. Zou (NSSC), K. Feng, Y. M. Zhang (AIR),
(The GECAM Mission Team) report:

During the commissioning phase, one satellite of GECAM mission, GECAM-B,
was triggered by a short GRB 210119A or a new SGR candidate
Swift J1851.2-6148 at 2021-01-19T02:54:09.850 (T0).
This burst was also observed by Fermi/GBM (GCN #29322), Swift/BAT
(GCN #29323) and Insight-HXMT (GCN #29329).

According to the GECAM-B light curves in about 8 keV-4 MeV,
this burst consists of a single pulse with a duration (T90) of
38.03 +/- 0.62 ms. The 20-ms peak counts rate is about 7000 cps while the
total counts is about 360 counts. A prominent spectral variation across
the burst duration is evident especially below 25 keV. The spectral
hardness measured by GECAM-B suggests that this bust is more likely
a short GRB rather than a typical SGR.

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/GECAM-B-tn210119_025409.png

Although the in-flight calibration of energy response and localization
has not been finalized yet, and this burst is rather short and weak,
GECAM-B localized this burst to the following position (J2000):
ra: 284.3 deg
dec: -60.4 deg
err: 6.4 deg
which is consistent with the position given by Swift/BAT 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.

This is the first published burst detected by GECAM mission.

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: GRB210119A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29332
SUBJECT: GRB 210119A (Swift J1851.2-6148): Swift-BAT refined analysis
DATE:    21/01/20 02:44:32 GMT
FROM:    Hans Krimm at NSF/NASA-GSFC  <hkrimm@nsf.gov>

T. N. Ukwatta (LANL), S. D. Barthelmy (GSFC), H. A. Krimm (NSF),
S. Laha (GSFC/UMBC), M. J. Moss (GWU), A. Y. Lien (GSFC/UMBC),
C. B. Markwardt (GSFC), D. M. Palmer (LANL), 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 Swift/BAT trigger #1017711
(Moss, et al., GCN Circ. 29323).  The BAT ground-calculated position is
RA, Dec = 282.822, -61.767 deg which is 
  RA(J2000)  =  18h 51m 17.4s 
  Dec(J2000) = -61d 45' 59.7" 
with an uncertainty of 1.5 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 92%.

The mask-weighted light curve shows a single spike with a FRED-like shape,
rising sharply at T+0 sec and decaying to background by T+0.1 sec. 
T90 (15-350 keV) is 0.06 +- 0.02 sec (estimated error including systematics).

The time-averaged spectrum from T+0.00 to T+0.08 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.41 +- 0.22.  The fluence in the 15-150 keV band is 7.1 +- 0.9 x 10^-8 erg/cm2.
The 1-sec peak photon flux measured from T-0.46 sec in the 15-150 keV band
is 1.0 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level. 

In the original GCN circular, it was discussed that this event could be either a
previously unknown Soft Gamma Repeater (Swift J1851.2-6148) or short GRB 210119A.
While the BAT data alone is insufficient for us to make a definitive judgement as to the
nature of the source, our assessment of these data suggests that the event was more 
likely a short GRB for the following reasons.  First, the spectrum is rather hard, and the
position of the burst on the T90-hardness diagram is within the population of short GRBs.
Second, the light curve shows a FRED (fast rise, exponential decay) profile, more 
consistent with a GRB than with an SGR flare.  Third, the event location is 35 degrees 
away from the center of the galactic bulge.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/01017711000/BA/


GRB_name: GRB210112A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29333
SUBJECT: GRB 210112A: 3.6m DOT optical detection
DATE:    21/01/20 06:14:31 GMT
FROM:    Dimple Panchal at ARIES, India  <dimplepanchal96@gmail.com>

Dimple (ARIES), K. Misra (ARIES), A. Ghosh (ARIES), R. Gupta (ARIES),  A.
Kumar (ARIES), S.B. Pandey (ARIES) report:

We carried out the follow-up observations of GRB 210112A (Ambrosi et al.
GCN #29289) with Aries Devasthal Faint Object Spectrograph and Camera
(ADFOSC) mounted on the 3.6m Devasthal Optical Telescope (DOT) at Devasthal
observatory of Aryabhatta Research Institute of observational sciencES
(ARIES), India. The observations started on 2021-01-13 at 23:59:18 UT in
i-band (sdss). We observed a series of 6 images with an exposure time of
300 seconds each. We detect the afterglow at 1.933 days after the burst,
reported by Ambrosi et al. GCN #29289; Ursi et al. GCN #29293;  Kann et al.
GCNs #29296,29300; Siegel et al. GCN #29303, in i-band with a magnitude of
23.19 +- 0.166 (AB mag), calibrated with the nearby PanSTARRS field. Our
results are consistent with the power-law decay index of 0.8 reported by
Kann et al. #29296.

The magnitude is not corrected for Galactic extinction in the direction of
the burst.


GRB_name: GRB210120A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29334
SUBJECT: GRB 210120A: Fermi GBM Final Real-time Localization
DATE:    21/01/20 07:21:03 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 07:10:44 UT on 20 Jan 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210120A (trigger 632819449.704302 / 210120299).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 163.4, Dec = 17.1 (J2000 degrees, equivalent to J2000 10h 53m, 17d 06'), with a statistical uncertainty of 3.8 degrees.

The angle from the Fermi LAT boresight is 83.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210120299/quicklook/glg_skymap_all_bn210120299.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/bn210120299/quicklook/glg_healpix_all_bn210120299.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210120299/quicklook/glg_lc_medres34_bn210120299.gif


GRB_name: GRB210120A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29335
SUBJECT: GRB 210120A: BALROG localization (Fermi Trigger 632819449 / GRB 210120299)
DATE:    21/01/20 07:43:15 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
632819449 at 07:10:44 on 20 Jan. 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) = 163.5+/-2.8 deg
Decl.(2000.0) = 17.0+/-2.2 deg
We estimate an additional systematic error of 1 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB210120299/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB210120299/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB210120299/json

                        


GRB_name: GRB210120A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29336
SUBJECT: Fermi GRB 210120A: Global MASTER-Net observations report 
DATE:    21/01/20 09:00:10 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 210120A ( Fermi GBM team, GCN 29334) errorbox  80 sec after notice time and 143 sec after trigger time at 2021-01-20 07:13:07 UT, with upper limit up to  19.5 mag. The observations began at zenith distance = 50 deg. The sun  altitude  is -27.8 deg. 

The galactic latitude b = 61 deg., longitude l = 228 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1529824

We obtain a following upper limits.  

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

     158 | 2021-01-20 07:13:07 |         MASTER-OAFA | (11h 02m 27.64s , +18d 11m 39.0s) |   C |    30 | 18.3 |        
     214 | 2021-01-20 07:13:58 |         MASTER-OAFA | (11h 02m 27.67s , +18d 10m 13.7s) |   C |    40 | 18.4 |        
     279 | 2021-01-20 07:14:58 |         MASTER-OAFA | (11h 02m 30.93s , +18d 11m 51.7s) |   C |    50 | 19.0 |        
     353 | 2021-01-20 07:16:07 |         MASTER-OAFA | (11h 02m 25.55s , +18d 10m 58.1s) |   C |    60 | 18.8 |        
     646 | 2021-01-20 07:20:30 |         MASTER-OAFA | (10h 52m 05.03s , +16d 29m 39.0s) |   C |   120 | 19.2 |        
     795 | 2021-01-20 07:22:49 |         MASTER-OAFA | (10h 52m 11.15s , +16d 29m 48.7s) |   C |   140 | 19.4 |        
     974 | 2021-01-20 07:25:29 |         MASTER-OAFA | (10h 52m 07.89s , +16d 31m 35.3s) |   C |   180 | 19.5 |        
    1174 | 2021-01-20 07:28:48 |         MASTER-OAFA | (10h 52m 07.90s , +16d 30m 04.6s) |   C |   180 | 19.4 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB210104A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29337
SUBJECT: GRB 210104A: 3.6m DOT optical upper limit
DATE:    21/01/20 11:44:16 GMT
FROM:    Dimple Panchal at ARIES, India  <dimplepanchal96@gmail.com>

Dimple (ARIES), K. Misra (ARIES), A. Ghosh (ARIES), R. Gupta (ARIES),  A.
Kumar (ARIES), S.B. Pandey (ARIES) report:

We observed the field of GRB 210104A (Troja et al. GCN #29233) with Aries
Devasthal Faint Object Spectrograph and Camera (ADFOSC) mounted on the 3.6m
Devasthal Optical Telescope (DOT). The observations started on 2021-01-13
at 19:52:50 UT (9.374 days after the burst). We obtained a set of
consecutive images with short exposure times to avoid saturation from the
nearby bright star. We do not detect any optical counterpart upto a
magnitude limit of 23.2 in the stacked image.


GRB_name: GRB210120A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29338
SUBJECT: GECAM In-Flight Trigger of GRB 210120A
DATE:    21/01/20 14:43:51 GMT
FROM:    Shaolin Xiong at IHEP  <xiongsl@ihep.ac.cn>

Z. H. An, C. Cai, G. Chen, W. Chen, M. Gao, M. Y. Ge, K. Gong, D. Y. Guo,
J. J. He, Y. Huang, B. Li, C. Li, C. Y. Li, J. H. Li, M. S. Li, Q. X. Li,
X. B. Li, X. Q. Li, Y. G. Li, X. H. Liang, J. Y. Liao, J. C. Liu, X. J. Liu,
Y. Q. Liu, F. J. Lu, Q. Luo, X. Ma, G. Ou, W. X. Peng, R. Qiao, J. Y. Shi,
D. L. Shi, L. M. Song, X. Y. Song, G. X. Sun, X. L. Sun, Y. L. Tuo,
J. Z. Wang, C. W. Wang, P. Wang, W. S. Wang, X. Y. Wen, S. Xiao,
S. L. Xiong, Y. B. Xu, Y. P. Xu, W. C. Xue, S. Yang, M. Yao, Q. B. Yi,
K. Zhang, P. Zhang, D. L. Zhang, F. Zhang, H. M. Zhang, S. N. Zhang,
Y. Q. Zhang, Z. Zhang, S. Y. Zhao, X. Y. Zhao, Y. Zhao, C. Zheng,
S. J. Zheng (IHEP), L. Chang, W. W. Chen, Y. M. Chen, L. Dong, X. B. Han,
J. Huang, J. Huang, C. Y. Ji, Y. C. Ji, F. Li, M. Y. Li, Z. D. Li,
Y. F. Lu, Y. Pang, J. L. Qi, J. G. Rong, Q. Q. Wang, Z. Wang, Y. Yang,
J. P. Yu, S. M. Yu, K. K. Zhang, D. K. Zhou (IAMCAS), M. Bai, T. Hu, Z. Ji,
Y. R. Liu, J. Su, C. X. Tian, J. Z. Tong, H. Y. Wu, Q. S. Yu, J. Zhong,
Z. M. Zou (NSSC), X. X. Feng (AIR),
(The GECAM Mission Team) report:

During the commissioning phase, one satellite of GECAM mission, GECAM-B,
was triggered by a long GRB 210120A at 2021-01-20T07:10:48.550 (T0),
which was also observed by Fermi/GBM (GCN #29334, 29335).

This burst was triggered, localized and classified as unknown source by
the GECAM In-Flight Trigger and Localization Software and
then 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 (including in-flight trigger
and location results) relative to the trigger time is about 60 seconds.
All other messages (including light curves data) for this trigger arrived
within about 10 minutes.

We made the quick-look light curve and the on-ground localization using the
alert data. The quick-look light curve shows that this burst mainly consists
of a single peak with a duration of about 20 s.
Although the in-flight calibration of energy response and localization
has not been finalized yet, the quick-look location is generally consistent
with the position given by Fermi/GBM within the error.
As the detailed science data are downloaded, all analyses including
localization would be further improved.

The GECAM quick-look light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/utn210120_071048_GECAMb.png

The GECAM quick-look location (preliminary) could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/utn210120_071048_GECAMb_Localization.png

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

This is the first GECAM GRB which was triggered and localized in-flight
with alert data promptly downlinked to ground successfully.

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: GRB210120A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29339
SUBJECT: GRB 210120A: MASTER OT (possibly) discovery
DATE:    21/01/20 20:41:29 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs  <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E.Gorbovskoy,N.Tiurina,P.Balanutsa,F.Balakin, V.Vladimirov, A.Kuznetsov,K.Zhirkov,D. Vlasenko, I.Gorbunov, D.Zimnukhov, 
V.Senik, A.Chasovnikov,A.Pozdnyakov,V.Topolev, D.Cheryasov(Lomonosov Moscow State University, SAI, Physics Department),
R. Podesta, C.Lopez, F. Podesta, C.Francile (Observatorio Astronomico FelixAguilar 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, Yu. Sergienko (Blagoveschensk Educational StateUniversity)

MASTER-OAFA robotic telescope (MASTER-Net: http://observ.pereplet.ru  Lipunov et al.,2010,Advances in Astronomy,2010,30L)
automatically was pointed (Lipunov et al. GCN 29336)
to Fermi GRB210120A (Ttrigger=07:10:44UT, Fermi GCN 29334, BALROG localization Biltzinger et al. GCN 29335,
Barthelmy https://gcn.gsfc.nasa.gov/other/210120A.gcn3 )
80s after notice time (143s after trigger time) at 2021-01-20 07:13:07UT

At first images MASTER auto-detection system found fast changing optical transient
  MASTER OT J105242.66+152355.0 / AT2021axc
at (RA, Dec) = 10h 52m 42.66s +15d 23m 55.0s at 2021-01-20 07:20:30UT
with unfiltered m_OT=18.6 at the beginning stage.

The OT is seen at several images. There is no any sources at this place in 
MASTER database since 2004.

The nearest source in VIZIER is SDSS galaxy in 4.9" with rmag(as most 
closest to MASTER unfiltered)=22.217 (22.088 in PanSTARRS)

The reduction will be continued.
This message may be cited.


GRB_name: GRB210116A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29340
SUBJECT: GRB 210116: AstroSat LAXPC detection
DATE:    21/01/21 07:51:44 GMT
FROM:    Tilak Katoch at TIFR  <tilak@tifr.res.in>

H. M. Antia, Tilak Katoch, Parag Shah and Dhiraj Dedhia
TIFR, Mumbai, India.

Analysis of AstroSat LAXPC data showed the detection of a long
GRB 210116. The light curve showed a peak profile triggered at
T0 = 05h 53m 33s UT on 16 Jan 2021. The light curve showed a peak
profile with T90 = 9 sec. The measured peak count rate above the
background associated with the burst is 867 +/- 37 cts/s in
LAXPC10 and 773 +/- 31 cts/s in LAXPC20 at T0+4 sec. The total
counts in the peak are 3219 +/- 85 cts in LAXPC10 and 2683 +/- 68
in LAXPC 20.

Both LAXPC instruments (LAXPC10 and LAXPC20) have registered this
burst profile in the light curve. For LAXPC20 the nominal energy
range is 3-100 keV, but due to lower gain in LAXPC10 the energy
range is about 30-400 keV.

The background subtracted light curve with 1 sec time-bin is
available at the web-site:
https://www.tifr.res.in/~astrosat_laxpc/grb210116lc.jpg

LAXPC was built by TIFR in collaboration with the Indian Space
Research Organisation. The Indian Space Research Organisation
funded, managed and facilitated the project.


GRB_name: GRB210120A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29341
SUBJECT: GRB 210120A(MASTER OT J105242.66+152355.0 / AT2021axc): Mondy optical observations
DATE:    21/01/21 09:08:59 GMT
FROM:    Alexei Pozanenko at IKI, Moscow  <apozanen@iki.rssi.ru>

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

We observed the MASTER OT J105242.66+152355.0 / AT2021axc (Lipunov et 
al., GCN 29339) in the field of Fermi GRB 210120A  (Fermi GBM Team, GCN 
29334; Biltzinger et al. GCN 29335) with AZT-33IK telescope of Sayan 
observatory (Mondy) starting on 2021-01-20 (UT) 20:57:41. The candidate 
in optical afterglow (Lipunov et al., GCN 29339) is well detected in our 
R-filter stacked image at R = 22.14 +/- 0.27 with 3 sigma upper limit of 
the field for point-like source R=22.3.  We confirm fading nature of the 
transient and support it for afterglow candidate of GRB 210112A.

Preliminary photometry of the optical transient in the stacked image is 
following

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

2021-01-20 20:57:41   0.59510    R      30*120  22.14 0.27  22.3


The photometry is based on the nearby USNO-B1.0 stars
USNO-B1.0_id R2
1053-0195054 16.13
1053-0195003 18.57


GRB_name: GRB210116A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29342
SUBJECT: GRB 210116A: AstroSat CZTI detection
DATE:    21/01/22 03:24:25 GMT
FROM:    Gaurav Waratkar at IIT Bombay  <gauravwaratkar24@gmail.com>

D. Nadella (NITK), G. Waratkar (IITB), A. Vibhute (IUCAA), S. Gupta
(IUCAA), P. Sawant (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 bright long GRB 210116A, which was
also detected by AstroSat LAXPC (GCN #29340).

The source was clearly detected in the 20-200 keV energy range. The light
curve showed a single strong peak at 2021-01-16 05:53:37.500 UT, in all
four quadrants of CZTI. Quadrant D was noisy, and we exclude it from
further analysis. The measured peak count rate associated with the burst is
781 (+54, -60) cts/s above the background in the combined data of three
quadrants (out of four), with a total of 3156 (+232, -222) cts. The local
mean background count rate was 395 (+3, -3) cts/s. Using cumulative rates,
we measure a T90 of 9.5 (+4.1, -1.8) s.

It was also clearly detected in the CsI anticoincidence (Veto) detector in
the 100-500 keV energy range. The light curve showed a single strong peak
of emission in all four quadrants, with the strongest peak consistent with
the above timing. The measured peak count rate is 3039 (+131, -62) cts/s
above the background in the combined Veto data of four quadrants, with a
total of 13614 (+475, -578) cts. The local mean background count rate was
1842 (+6, -6) cts/s. We measure a T90 of 8.8 (+1.7, -1.0) 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: GRB210116A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29344
SUBJECT: ZTF21aaeyldq: GROND and CAHA jet break confirmation
DATE:    21/01/22 17:37:47 GMT
FROM:    Alexander Kann at IAA-CSIC  <kann@iaa.es>

D. A. Kann (HETH/IAA-CSIC), A. Nicuesa Guelbenzu (TLS Tautenburg), A. de 
Ugarte Postigo (HETH/IAA-CSIC, DARK/NBI), C. C. Thoene (HETH), M. 
Blazek, J. F. Agui Fernandez (both HETH/IAA-CSIC), A. Rau (MPE 
Garching), S. Klose (TLS Tautenburg), and J. I. Vico Linares (CAHA) 
report:

We obtained further observations of the GRB-less afterglow 
ZTF21aaeyldq/AT2021any (Ho et al., GCN #29305; de Ugarte Postigo et al., 
GCN #29307) with CAFOS at the 2.2m telescope at Calar Alto, Almeria, 
Spain, in the Rc band at 2.8 days post-discovery, and with GROND mounted 
at the 2.2m MPG telescope at the ESO La Silla Observatory (Chile) at 3.9 
days after the trigger. The afterglow is clearly detected in each 
stacked image.

Further to the observations and analysis described in Kann et al. (GCN 
#29321, with data from Ho et al., GCN #29305; de Ugarte Postigo et al., 
GCN #29307; and Zhu et al., GCN #29310) and Nicuesa Guelbenzu et al. 
(GCN #29330), we fit the combined data set, also leaving the host-galaxy 
magnitudes free, as the GROND data shows a characteristic flattening.

We find that a single power-law fit does not describe the data well 
(chi^2/d.o.f. = 3.7), overestimating the CAHA data and not fitting the 
curvature seen in the GROND data. However, a broken power-law fit yields 
a significantly improved result (chi^2/d.o.f. = 0.12) with fit 
parameters alpha_1 = 0.95 +/- 0.03, alpha_2 = 2.30 +/- 0.76 and t_b = 
0.82 +/- 0.08 days. This fit may be improved or modified with further 
data/observations, but the break signature is clear. It therefore 
confirms the initial suggestion of Kann et al. (GCN #29321). This is a 
typical feature in GRB afterglows and a further indicator that the 
nature of this transient is a GRB afterglow.

Ho et al., GCN #29305, report the first detection at 
2021-01-16T06:59:45.6, and a deep non-detection 22 minutes earlier. 
Antia et al., GCN #29340, and Nadella et al., GCN #29342, report the 
detection of a bright GRB 210116A with AstroSat LAXPC and CZTI at ~05:53 
UR on the same day, about 44 minutes before the ZTF non-detection. 
Judging from typical GRB afterglow behavior, this makes it unlikely that 
the two events are associated with each other but does not rule it out. 
An IPN localization of GRB 210116A could confirm or rule out the 
association.


GRB_name: GRB210120A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29345
SUBJECT: GRB 210120A : 1.3m DFOT optical observations
DATE:    21/01/22 20:35:52 GMT
FROM:    Dimple Panchal at ARIES, India  <dimplepanchal96@gmail.com>

Dimple (ARIES), A. Ghosh (ARIES), R. Gupta (ARIES), A. Kumar (ARIES), K.
Misra (ARIES), S.B. Pandey (ARIES) report:

We carried out the follow-up observations of  the MASTER OT
J105242.66+152355.0 / AT2021axc (Lipunov et al., GCN  #29339) in the field
of Fermi GRB 210120A  (Fermi GBM Team, GCN
29334; Biltzinger et al., GCN #29335) with 1.3m Devasthal Fast Optical
Telescope (DFOT) at Devasthal observatory of Aryabhatta Research Institute
of observational sciencES (ARIES), India. The observations started on
2021-01-21 at 20:51:55 in R-band. We observed a set of 18 images with an
exposure time of 300 seconds each, centered at 1.5937 days after the burst.
We clearly detect the optical afterglow candidate reported by  Lipunov
et al., GCN  #29339  in the stacked image with a magnitude of  22.60+-0.16. The
object is fading with time (S. Belkin et al. GCN #29341; Lipunov et al.,
GCN  #29339) which supports it as an afterglow candidate for GRB 210120A.

The magnitude is not corrected for the Galactic extinction in the direction
of the burst. The photometric calibration is performed using the standard
stars from the USNO-B1.0 catalog.


GRB_name: GRB210121A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29346
SUBJECT: GRB 210121A: Insight-HXMT/HE detection
DATE:    21/01/23 01:57:30 GMT
FROM:    Wangchen Xue at IHEP  <xuewc@ihep.ac.cn>

W. C. Xue, C. Cai, J. C. Liu, Q. Luo, S. Xiao, 
Q. B. Yi, Y. Q. Zhang, C. Zheng, Y. Huang, C. K. Li, 
G. Li, X. B. Li, J. Y. Liao, X. Y. Song, S. L. Xiong, C. Z. Liu, 
X. F. Li, Z. W. Li, Z. Chang, A. M. Zhang, Y. F. Zhang, 
X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), 
T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, 
M. Wu, Y. P. Xu, S. N. Zhang (IHEP), 
report on behalf of the Insight-HXMT team:

At 2021-01-21T18:41:48.750 (T0), Insight-HXMT/HE detected 
GRB 210121A (trigger ID: HEB210121779) in a routine search of the data.

The Insight-HXMT/HE light curve mainly consists of multiple
pulses with a duration (T90) of 13.24 s measured from T0+0.27 s. 
The 1-ms peak rate, measured from T0+0.52 s, is 10996 cnts/sec. 
The total counts from this burst is 45848 counts. 
URL_LC: http://twiki.ihep.ac.cn/pub/HXMT/GRBList/HEB210121779_lc.jpg

All measurements above are made with the CsI detectors operating in the 
GRB mode with the energy range of about 80-800 keV (deposited energy). 
Only gamma-rays with energy greater than about 200 keV can penetrate 
the spacecraft and leave signals in the CsI detectors installed inside 
of the telescope. 

Insight-HXMT is the first Chinese space X-ray telescope, which was 
funded jointly by the China National Space Administration (CNSA) and 
the Chinese Academy of Sciences (CAS). 
More information about it could be found at: 
http://www.hxmt.org.


GRB_name: GRB210121A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29347
SUBJECT: GRB 210121A: GECAM detection
DATE:    21/01/23 15:34:41 GMT
FROM:    Shaolin Xiong at IHEP  <xiongsl@ihep.ac.cn>

W. X. Peng, S. Xiao, C. Cai, Y. Zhao, P. Wang, S. L. Xiong,
Z. H. An, C. Chen, G. Chen, W. Chen, M. Gao, K. Gong, D. Y. Guo,
J. J. He, Y. Huang, B. Li, C. Li, C. Y. Li, J. H. Li, Q. X. Li,
X. B. Li, X. Q. Li, Y. G. Li, X. H. Liang, J. Y. Liao, J. C. Liu,
X. J. Liu, Y. Q. Liu, F. J. Lu, Q. Luo, X. Ma, G. Ou, R. Qiao,
D. L. Shi, J. Y. Shi, L. M. Song, X. Y. Song, G. X. Sun, X. L. Sun,
Y. L. Tuo, C. W. Wang, J. Z. Wang, X. Y. Wen, Y. B. Xu, Y. P. Xu,
W. C. Xue, S. Yang, M. Yao, Q. B. Yi, C. Y. Zhang, D. L. Zhang, Fan Zhang,
Fei Zhang, H. M. Zhang, K. Zhang, P. Zhang, S. N. Zhang, Y. Q. Zhang,
Z. Zhang, S. Y. Zhao, X. Y. Zhao, C. Zheng, S. J. Zheng, X. Zhou (IHEP),
report on behalf of GECAM team:

During the commissioning phase, GECAM-B was triggered by a long GRB 210121A
at 2021-01-21T18:41:48.800 UTC (denoted as T0), which was also observed by
Insight-HXMT/HE (GCN # 29346) and Konus-Wind.

According to the GECAM-B light curves in about 8 keV-4 MeV,
this burst mainly consists of multiple pulses with T90 of 15.0 +/- 0.3 s
measured from T0+0.20 s. The 1-s peak counts rate is about 13108 cps
while the total counts is about 109051 counts.

Spectral evolution is clearly detected during the burst, and
the emissions in low energies last longer than that in high energies.

Although the in-flight calibration of energy response and localization
has not been finalized yet,
GECAM-B localized this burst to the following position (J2000):
Ra: 23.3 deg
Dec: -47.7 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 light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/utn210121_184148_GECAMb.pdf

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: GRB210121A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29348
SUBJECT: IPN triangulation of GRB 210121A
DATE:    21/01/23 22:15:41 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@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,

D. Svinkin, S. Golenetskii, D. Frederiks, A. Ridnaia,
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,

and

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

The long-duration, bright GRB 210121A
(Insight-HXMT/HE detection: Xue et al., GCN Circ. 29346
GECAM detection: Peng et al., GCN Circ. 29347)
has been detected by Konus-Wind, Mars-Odyssey (HEND),
INTEGRAL (SPI-ACS), Insight (HXMT/HE), and GECAM, so far,
at about 67309 s UT (18:41:49).

We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
    16.981 (01h 07m 55s) -46.401 (-46d 24' 04")
  Corners:
    17.388 (01h 09m 33s) -46.452 (-46d 27' 06")
    17.369 (01h 09m 29s) -46.539 (-46d 32' 20")
    16.575 (01h 06m 18s) -46.348 (-46d 20' 54")
    16.595 (01h 06m 23s) -46.261 (-46d 15' 40")
  ---------------------------------------------
The error box area is 181 sq. arcmin, and its maximum
dimension is 36 arcmin (the minimum one is 5 arcmin).
The Sun distance was 64 deg.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB210121_T67306/IPN

The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.


GRB_name: GRB210123A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29349
SUBJECT: GRB 210123A: Insight-HXMT/HE detection
DATE:    21/01/24 05:44:27 GMT
FROM:    Wangchen Xue at IHEP  <xuewc@ihep.ac.cn>

W. C. Xue, C. Cai, J. C. Liu, Q. Luo, S. Xiao, 
Q. B. Yi, Y. Q. Zhang, C. Zheng, Y. Huang, C. K. Li, 
G. Li, X. B. Li, J. Y. Liao, X. Y. Song, S. L. Xiong, C. Z. Liu, 
X. F. Li, Z. W. Li, Z. Chang, A. M. Zhang, Y. F. Zhang, 
X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), 
T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, 
M. Wu, Y. P. Xu, S. N. Zhang (IHEP), 
report on behalf of the Insight-HXMT team:

At 2021-01-23T07:19:10.350 (T0), Insight-HXMT/HE detected 
GRB 210123A (trigger ID: HEB210123304) in a routine search of the data, 
which also triggered INTEGRAL and IPN.

The Insight-HXMT/HE light curve mainly consists of multiple
pulses with a duration (T90) of 6.56 s measured from T0-0.52 s. 
The 1-ms peak rate, measured from T0+1.95 s, is 1825 cnts/sec. 
The total counts from this burst is 5536 counts. 
URL_LC: http://twiki.ihep.ac.cn/pub/HXMT/GRBList/HEB210123304_lc.jpg

All measurements above are made with the CsI detectors operating in the 
GRB mode with the energy range of about 80-800 keV (deposited energy). 
Only gamma-rays with energy greater than about 200 keV can penetrate 
the spacecraft and leave signals in the CsI detectors installed inside 
of the telescope. 

Insight-HXMT is the first Chinese space X-ray telescope, which was 
funded jointly by the China National Space Administration (CNSA) and 
the Chinese Academy of Sciences (CAS). 
More information about it could be found at: 
http://www.hxmt.org.


GRB_name: GRB210124A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29350
SUBJECT: GECAM detection of a burst possibly from the X-ray burster 4U 0614+09 or GRB 210124A
DATE:    21/01/24 14:53:02 GMT
FROM:    Shaolin Xiong at IHEP  <xiongsl@ihep.ac.cn>

S. L. Xiong, F. J. Lu, S. N. Zhang, Y. Huang, Y. P. Chen,
S. Xiao, C. Cai, X. Y. Zhao, B. X. Zhang,
Z. H. An, C. Chen, G. Chen, W. Chen, M. Gao, K. Gong, D. Y. Guo,
J. J. He, B. Li, C. Li, C. Y. Li, J. H. Li, Q. X. Li,
X. B. Li, X. Q. Li, Y. G. Li, X. H. Liang, J. Y. Liao, J. C. Liu,
X. J. Liu, Y. Q. Liu, Q. Luo, X. Ma, G. Ou, W. X. Peng, R. Qiao,
D. L. Shi, J. Y. Shi, L. M. Song, X. Y. Song, G. X. Sun, X. L. Sun,
Y. L. Tuo, C. W. Wang, J. Z. Wang, P. Wang, X. Y. Wen, Y. B. Xu,
Y. P. Xu, W. C. Xue, S. Yang, M. Yao, Q. B. Yi, C. Y. Zhang,
D. L. Zhang, Fan Zhang, Fei Zhang, H. M. Zhang, K. Zhang, P. Zhang,
Y. Q. Zhang, Z. Zhang, S. Y. Zhao, Y. Zhao, C. Zheng,
S. J. Zheng, X. Zhou (IHEP),
report on behalf of GECAM team:

During the commissioning phase, GECAM-B was triggered in-flight by
a long burst at 2021-01-24T11:50:03.600 UTC (denoted as T0).
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
a single pulse with a duration of about 60 s.
The spectrum is very soft with not much emission above about 30 keV.
An automatic on-ground localization was calculated using the light curves
and spectrum. Although the in-flight calibration of energy response and
localization has not been finalized yet, GECAM-B localized this burst to
the following position (J2000):

Ra: 94.9 deg Dec: 6.6 deg
Galactic lon: 188.4 deg, lat: 12.1 deg
Err: 2.7 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 light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_lc_grd_21-22-11_65188203.png

The GECAM preliminary location could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_skymap_65188203_V01.png

Based on the light curve, spectral hardness and location, we suggest that
this burst is likely from a galactic source. We note that 4U 0614+09 lies
within the location error which could produce such an X-ray burst.
However, the GRB nature could not be ruled out yet.

As the detailed science data are downloaded, all analyses would be improved.

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: GRB210123A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29351
SUBJECT: GRB 210123A: Fermi GBM Final Localization
DATE:    21/01/25 21:39:52 GMT
FROM:    Rachel Dunwoody at UCD  <rachel.dunwoody@ucdconnect.ie>

The Fermi GBM team reports the detection of a likely long GRB.

"At 07:19:03.07 UT on 23 January 2021, the Fermi Gamma-Ray Burst Monitor
(GBM)
triggered and located GRB 210123A (trigger 633079148 / 210123305).

This burst was also independently detected by INTEGRAL SPI-ACS and
the Insight-HXMT/HE (Xue et al. 2019, GCN 29349)

The on-ground calculated location, using the GBM trigger
data, is RA = 345.1, DEC = -56.9 (J2000 degrees,
equivalent to 23h 00m, -56d 53'), with a statistical uncertainty
of 1.1 degrees.

The angle from the Fermi LAT boresight is 110 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210123305/quicklook/glg_skymap_all_bn210123305.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/bn210123305/quicklook/glg_healpix_all_bn210123305.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210123305/quicklook/glg_lc_medres34_bn210123305.gif


GRB_name: GRB210124B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29353
SUBJECT: GRB 210124B: Insight-HXMT/HE detection
DATE:    21/01/26 05:47:26 GMT
FROM:    Y Q Zhang at IHEP  <yqzhang@ihep.ac.cn>

J. C. Liu, C. Zheng, C. Cai,  Q. Luo, S. Xiao, 
W. C. Xue, Q. B. Yi, Y. Q. Zhang, Y. Huang, C. K. Li, 
G. Li, X. B. Li, J. Y. Liao, X. Y. Song, S. L. Xiong, C. Z. Liu, 
X. F. Li, Z. W. Li, Z. Chang, A. M. Zhang, Y. F. Zhang, 
X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), 
T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, 
M. Wu, Y. P. Xu, S. N. Zhang (IHEP), 
report on behalf of the Insight-HXMT team:

At 2021-01-24T13:23:48.400 (T0), Insight-HXMT/HE detected 
GRB 210124B (trigger ID: HEB210124558) in a routine search of the data.

The Insight-HXMT/HE light curve mainly consists of multiple 
pulses with a duration (T90) of 0.062 s measured from T0+0.01 s. 
The 1-ms peak rate, measured from T0+0.035 s, is 34250 cnts/sec. 
The total counts from this burst is 988 counts. 
URL_LC: http://twiki.ihep.ac.cn/pub/HXMT/GRBList/HEB210124558_lc.jpg

All measurements above are made with the CsI detectors operating in the 
GRB mode with the energy range of about 250-3000 keV (deposited energy). 
Only gamma-rays with energy greater than about 200 keV can penetrate 
the spacecraft and leave signals in the CsI detectors installed inside 
of the telescope. 

Insight-HXMT is the first Chinese space X-ray telescope, which was 
funded jointly by the China National Space Administration (CNSA) and 
the Chinese Academy of Sciences (CAS). 
More information about it could be found at: 
http://www.hxmt.org.


GRB_name: GRB210126A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29354
SUBJECT: GRB 210126A: BALROG localization (Fermi Trigger  / GRB 210126417)
DATE:    21/01/26 10:48:07 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
 at 10:00:05 on 26 Jan. 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) = 90.2+/-6.6 deg
Decl.(2000.0) = -66.0+/-3.3 deg
We estimate an additional systematic error of 1 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB210126417/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB210126417/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB210126417/json

                        


GRB_name: GRB210124B
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29355
SUBJECT: IPN triangulation of GRB 210124B (short)
DATE:    21/01/26 13:08:39 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@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,

D. Svinkin, S. Golenetskii, D. Frederiks, A. Ridnaia,
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,

and

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

The short-duration, bright GRB 210124B
(Insight-HXMT/HE detection: Liu et al., GCN Circ. 29353)
has been detected by Konus-Wind, Mars-Odyssey (HEND),
INTEGRAL (SPI-ACS), and Insight (HXMT/HE), so far,
at about 48220 s UT (13:23:40).

We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
  ---------------------------------------------
   RA(2000), deg                 Dec(2000), deg
  ---------------------------------------------
  Center:
   274.333 (18h 17m 20s)  -0.443 ( +0d 26' 36")
  Corners:
   274.258 (18h 17m 02s)  -0.358 ( +0d 21' 29")
   274.313 (18h 17m 15s)  -0.234 ( +0d 14' 01")
   274.409 (18h 17m 38s)  -0.529 ( +0d 31' 43")
   274.354 (18h 17m 25s)  -0.654 ( +0d 39' 15")
  ---------------------------------------------
The error box area is 101 sq. arcmin, and its maximum
dimension is 25 arcmin (the minimum one is 5.4 arcmin).
The Sun distance was 37 deg.

The box has rather low galactic latitude of 7.4 deg, but significant 
emission above ~300 keV provides strong evidence against SGR origin of 
this burst.

This box may be improved.

A triangulation map is posted at
http://www.ioffe.ru/LEA/GRBs/GRB210124_T48224/IPN

The Konus-Wind time history and spectrum will be given in a forthcoming
GCN Circular.


GRB_name: GRB210126A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29356
SUBJECT: GRB 210126A: GECAM detection
DATE:    21/01/26 14:16:02 GMT
FROM:    Shaolin Xiong at IHEP  <xiongsl@ihep.ac.cn>

D. Y. Guo, Y. Huang, R. Qiao, X. Ma, P. Zhang, F. J. Lu,
S. L. Xiong, S. Xiao, C. Cai, X. Y. Zhao, B. X. Zhang,
Z. H. An, C. Chen, G. Chen, W. Chen, M. Gao, K. Gong, D. Y. Guo,
J. J. He, B. Li, C. Li, C. Y. Li, J. H. Li, Q. X. Li,
X. B. Li, X. Q. Li, Y. G. Li, X. H. Liang, J. Y. Liao, J. C. Liu,
X. J. Liu, Y. Q. Liu, Q. Luo, G. Ou, W. X. Peng, R. Qiao,
D. L. Shi, J. Y. Shi, L. M. Song, X. Y. Song, G. X. Sun, X. L. Sun,
Y. L. Tuo, C. W. Wang, J. Z. Wang, P. Wang, X. Y. Wen, Y. B. Xu,
Y. P. Xu, W. C. Xue, S. Yang, M. Yao, Q. B. Yi, C. Y. Zhang,
D. L. Zhang, Fan Zhang, Fei Zhang, H. M. Zhang, K. Zhang,
S. N. Zhang, Y. Q. Zhang, Z. Zhang, S. Y. Zhao, Y. Zhao, C. Zheng,
S. J. Zheng, X. Zhou (IHEP),
report on behalf of GECAM team:

During the commissioning phase, GECAM-B was triggered in-flight by
a long burst at 2021-01-26T10:00:10.600 UTC (denoted as T0).
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 a duration of roughly 60 s.
An automatic on-ground localization was calculated using the light curves
and spectrum. Although the in-flight calibration of energy response and
localization has not been finalized yet, GECAM-B localized this burst to
the following position (J2000):

Ra: 112.9 deg Dec: -53.3 deg
Galactic lon: 266.6 deg, lat: -20.6 deg
Err: 6 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 light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_lc_grd_5-21-4_65354410.png

The GECAM preliminary location could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_skymap_65354410_V01.png

This burst is temporally and positional coincident with Fermi/GBM trigger
(trigNum 633348010, GCN #29354).

As the detailed science data are downloaded, all analyses would be improved.

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: GRB210124B
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29357
SUBJECT: Konus-Wind detection of GRB 210124B
DATE:    21/01/26 15:05:57 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

The short-duration, bright GRB 210124B
(Insight-HXMT/HE detection: Liu et al., GCN Circ. 29353;
IPN triangulatuion: Hurley et al., GCN Circ. 29355;)
triggered Konus-Wind at T0=48224.368 s UT (13:23:44.368).

The burst light curve shows a multipeaked structure
which starts at ~T0-20 ms and ends at ~T0+40 ms,
followed by a weaker emission seen up to ~T0+170 ms.
The total burst duration is ~0.2 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/GRB210124_T48224

As observed by Konus-Wind, the burst
had a fluence of 3.03(-0.71,+0.86)x10^-6 erg/cm2,
and a 16-ms peak flux, measured from T0-0.006 s,
of 6.16(-2.15,+2.54)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+0.064 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 = -0.93(-0.20,+0.25)
and Ep = 1544(-642,+1186) keV (chi2 = 33/20 dof).
Fitting by a GRB (Band) model yields the same alpha and Ep,
and an upper limit on the high energy photon index: beta < -1.5
(chi2 = 33/19 dof).

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB210121A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29358
SUBJECT: Konus-Wind detection of GRB 210121A
DATE:    21/01/26 16:18:39 GMT
FROM:    Dmitry Svinkin at Ioffe Institute  <svinkin@mail.ioffe.ru>

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

The long-duration, bright GRB 210121A
(Insight-HXMT/HE detection: Xue et al., GCN Circ. 29346
GECAM detection: Peng et al., GCN Circ. 29347;
IPN triangulation: Hurley et al., GCN Circ. 29348)
triggered Konus-Wind at T0=67306.174 s UT (18:41:46.174).

The burst light curve shows a multipeaked structure
which starts at ~T0-0.1 s and has a total duration of ~64 s.
The emission is seen up to ~7 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB210121_T67306/

As observed by Konus-Wind, the burst
had a fluence of 1.18(-0.10,+0.10)x10^-4 erg/cm2,
and a 64-ms peak flux, measured from T0+1.072 s,
of 3.00(-0.43,+0.43)x10^-5 erg/cm2/s
(both in the 20 keV - 10 MeV energy range).

The time-averaged spectrum of the burst
(measured from T0 to T0+22.784 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.59(-0.05,+0.06),
the high energy photon index beta = -3.03(-1.42,+0.43),
the peak energy Ep = 875(-69,+70) keV
(chi2 = 110/97 dof).

The spectrum near the maximum count rate
(measured from T0+0.256 s to T0+1.792 s)
is best fit in the 20 keV - 10 MeV range
by the GRB (Band) model with the following parameters:
the low-energy photon index alpha = -0.32(-0.08,+0.09),
the high energy photon index beta = -3.60(3.60,+0.68),
the peak energy Ep = 981(-88,+94) keV
(chi2 = 82/97 dof).

All the quoted errors are at the 90% confidence level.
All the quoted values are preliminary.


GRB_name: GRB210120A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29361
SUBJECT: GRB 210120A: Fermi GBM detection
DATE:    21/01/27 01:39:51 GMT
FROM:    Stephen Lesage at Fermi-GBM Team  <sjl0014@uah.edu>

S. Lesage (UAH), R. Dunwoody (UCD), J. Mangan (UCD), C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 07:10:44.70 UT on 20 January 2021, the Fermi Gamma-Ray Burst Monitor
(GBM)
triggered and located GRB 210120A (trigger 632819449 / 210120.299),
the optical counterpart for which was detected by MASTER (Lipunov et al.
2021,
GCN 29339) and confirmed (Pozanenko et al. 2021, GCN 29341; Dimple et al.
2021,
GCN 29345). The GBM Fermi GBM Final Real-time Localization (GCN 29334) is
consistent
with the MASTER OT follow-up observations.

The angle from the Fermi LAT boresight at the GBM trigger time is 82
degrees.

The GBM light curve consists of a single peak
with a duration (T90) of about 22.2 s (50-300 keV).
The time-averaged spectrum from T0-0.32 s to T0+22.21 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.62 +/- 0.12 and
the cutoff energy, parameterized as Epeak, is 94 +/- 6 keV

The event fluence (10-1000 keV) in this time interval is
(2.9 +/- 0.1)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+ 2.6 s in the 10-1000 keV band
is 3.6 +/- 0.2 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak= 95 +/- 6 keV, alpha = -0.63 +/- 0.12 and beta = -29 +/- 6E12.

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: GRB210127A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29362
SUBJECT: GRB 210127A: Fermi GBM Final Real-time Localization
DATE:    21/01/27 06:36:33 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 06:26:17 UT on 27 Jan 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210127A (trigger 633421582.019982 / 210127268).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 54.2, Dec = 41.8 (J2000 degrees, equivalent to J2000 03h 36m, 41d 47'), with a statistical uncertainty of 18.1 degrees.

The angle from the Fermi LAT boresight is 31.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210127268/quicklook/glg_skymap_all_bn210127268.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/bn210127268/quicklook/glg_healpix_all_bn210127268.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210127268/quicklook/glg_lc_medres34_bn210127268.gif


GRB_name: GRB210123A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29366
SUBJECT: GRB 210123A: AstroSat CZTI detection
DATE:    21/01/29 05:46:19 GMT
FROM:    Gaurav Waratkar at IIT,Bombay  <gauravwaratkar@iitb.ac.in>

D. Nadella (NITK), G. Waratkar (IITB), A. Vibhute (IUCAA), S. Gupta 
(IUCAA), P. Sawant (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 210123A, which 
was also detected by Insight-HXMT/HE (GCN #29349) and Fermi-GBM (GCN 
#29351).

The source was detected in the 20-200 keV energy range. The light curve 
showed a single peak of emission at 2021-01-23 07:19:08.5 UT. Quadrant A 
was noisy, and we exclude it from further analysis. The measured peak 
count rate associated with the burst is 205 (+40, -38) cts/s above the 
background in the combined data of three quadrants (out of four), with a 
total of 996 (+259, -237) cts. The local mean background count rate was 
394 (+3, -3) cts/s. Using cumulative rates, we measure a T90 of 14 (+5, 
-4) 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 2021-01-23 07:19:09.1 UT in all 
four quadrants. The measured peak count rate is 1710 (+95, -102) cts/s 
above the background in the combined Veto data of four quadrants, with a 
total of 8982 (+648, -679) cts. The local mean background count rate was 
1817 (+5, -7) cts/s. We measure a T90 of 14 (+5, -1) 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: GRB210124B
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29367
SUBJECT: GRB 210124B: AstroSat CZTI detection
DATE:    21/01/29 06:12:31 GMT
FROM:    Gaurav Waratkar at IIT,Bombay  <gauravwaratkar@iitb.ac.in>

D. Nadella (NITK), G. Waratkar (IITB), A. Vibhute (IUCAA), S. Gupta
(IUCAA), P. Sawant (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 the short GRB 210124B, which
was also detected by Insight-HXMT/HE (GCN #29353) & Konus-Wind (GCN
#29357).

The source was clearly detected in the 20-200 keV energy range in all
four quadrants. Quadrant D was noisy, and we excluded it from further
analysis. The light curve showed multiple peaks of emission with the
strongest peak at 2021-01-24 13:23:45.43 UT. The measured peak count
rate associated with the burst is 2348 (+928, -540) cts/s above the
background in the combined data of three quadrants, with a total of 88
(+52, -26) cts. The local mean background count rate was 362 (+2, -25)
cts/s. Using cumulative rates, we measure a T90 of 0.07 (+0.35, -0.04)
s.

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: GRB210126A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29368
SUBJECT: GRB 210126A: AstroSat CZTI detection
DATE:    21/01/29 07:39:06 GMT
FROM:    Gaurav Waratkar at IIT,Bombay  <gauravwaratkar@iitb.ac.in>

D. Nadella (NITK), G. Waratkar (IITB), A. Vibhute (IUCAA), S. Gupta
(IUCAA), P. Sawant (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 210126A, which
was also detected by Fermi-GBM (GCN #29354) and GECAM-B (GCN #29356). 

The source was detected in the 20-200 keV energy range in three
quadrants (Quadrant A, C, and D). Quadrant D was noisy, and we excluded
it from further analysis. The light curve showed multiple peaks of
emission with the strongest peak at 2021-01-26 10:00:07 UT. The measured
peak count rate associated with the burst is 56 (+9, -10) cts/s above
the background in the combined data of two quadrants, with a total of
1039 (+412, -454) cts. The local mean background count rate was 248 (+1,
-1) cts/s. Using cumulative rates, we measure a T90 of 67 (+41, -55) s.
These large error bars arise from the presence of a weak second peak
whose association with the burst is ambiguous in our data. 

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: GRB140104B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29369
SUBJECT: GRB 140104B: Swift-XRT refined Analysis
DATE:    21/01/29 14:51:41 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), D.N. Burrows (PSU), J. D. Gropp
(PSU), J.A. Kennea (PSU), K.L. Page (U. Leicester), A.P. Beardmore (U.
Leicester) and report on behalf of the Swift-XRT team: report on
behalf of the Swift-XRT team:

We have analysed 9.6 ks of XRT data for the Fermi/LAT-detected burst
GRB 140104B, from 55.4 ks to 833.9 ks after the  Fermi/LAT trigger. The
data are entirely in Photon Counting (PC) mode. The refined XRT
position is RA, Dec = 218.7543, -9.0282 which is equivalent to:

RA (J2000): 14 35 01.03
Dec(J2000): -09 01 41.5

with an uncertainty of 4.0 arcsec (radius, 90% confidence). This
position is 8.4 arcmin from the Fermi/LAT position.  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/00020337.

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


GRB_name: GRB140402A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29370
SUBJECT: GRB 140402A: Swift-XRT refined Analysis
DATE:    21/01/29 14:52:05 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), A. Tohuvavohu (U.
Toronto), K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), P.A.
Evans (U. Leicester) and J.R. Cummings report on behalf of the
Swift-XRT team: report on behalf of the Swift-XRT team:

We have analysed 4.5 ks of XRT data for the Fermi/GBM-detected burst
GRB 140402A (Cummings et al. GCN Circ. 16071), from 32.8 ks to 51.2 ks
after the  Fermi/GBM trigger. The data are entirely in Photon Counting
(PC) mode. The refined XRT position is RA, Dec = 207.5986, +5.7744
which is equivalent to:

RA (J2000): 13 50 23.67
Dec(J2000): +05 46 28.0

with an uncertainty of 5.6 arcsec (radius, 90% confidence). This
position is 9.6 arcmin from the Fermi/GBM position.  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/00020373.

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


GRB_name: GRB140320B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29371
SUBJECT: GRB 140320B: Swift-XRT refined Analysis
DATE:    21/01/29 14:52:13 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), A.P. Beardmore (U.
Leicester), P.A. Evans (U. Leicester), J.P. Osborne (U. Leicester), A.
Melandri (INAF-OAB) and C. Pagani report on behalf of the Swift-XRT
team: report on behalf of the Swift-XRT team:

We have analysed 6.0 ks of XRT data for the INTEGRAL-detected burst GRB
140320B (Pagani et al. GCN Circ. 16013), from 12.0 ks to 29.4 ks after
the  INTEGRAL trigger. The data are entirely in Photon Counting (PC)
mode. The refined XRT position is RA, Dec = 145.5611, +60.2690 which is
equivalent to:

RA (J2000): 09 42 14.66
Dec(J2000): +60 16 08.3

with an uncertainty of 3.6 arcsec (radius, 90% confidence). This
position is 51 arcsec from the INTEGRAL position.  We cannot determine
at the present time whether the source is fading.

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.4 (+0.4, -0.3). The
best-fitting absorption column is  7.2 (+7.1, -4.8) x 10^20 cm^-2,
consistent with 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 2.8 x 10^-11 (3.8 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      7.2 (+7.1, -4.8) x 10^20 cm^-2
Galactic foreground: 2.4 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:      2.4 (+0.4, -0.3)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00020370.

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


GRB_name: GRB140330A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29372
SUBJECT: GRB 140330A: Swift-XRT refined Analysis
DATE:    21/01/29 14:52:21 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), P.A. Evans (U. Leicester), J.P. Osborne (U.
Leicester), K.L. Page (U. Leicester), A. Melandri (INAF-OAB), T.
Sbarrato (INAF-OAB) and  report on behalf of the Swift-XRT team: report
on behalf of the Swift-XRT team:

We have analysed 3.2 ks of XRT data for the Fermi/LAT-detected burst
GRB 140330A, from 102.0 ks to 120.0 ks after the  Fermi/LAT trigger.
The data are entirely in Photon Counting (PC) mode. The refined XRT
position is RA, Dec = 325.4425, -64.1882 which is equivalent to:

RA (J2000): 21 41 46.19
Dec(J2000): -64 11 17.4

with an uncertainty of 4.0 arcsec (radius, 90% confidence). This
position is 7.7 arcmin from the Fermi/LAT position.  The source has a
mean count rate of 2.4e-02 ct/sec; we cannot determine at the present
time whether it is fading.

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.8 (+0.7, -0.5). The
best-fitting absorption column is  9 (+17, -5) x 10^20 cm^-2,
consistent with the Galactic value of 3.5 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 3.4 x 10^-11 (4.1 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      9 (+17, -5) x 10^20 cm^-2
Galactic foreground: 3.5 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.8 (+0.7, -0.5)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00020372.

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


GRB_name: GRB210129A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29376
SUBJECT: GRB 210129A: Insight-HXMT/HE detection
DATE:    21/01/31 12:05:48 GMT
FROM:    Y Q Zhang at IHEP  <yqzhang@ihep.ac.cn>

Y. Q. Zhang, C. Cai, J. C. Liu, Q. Luo, S. Xiao, 
W. C. Xue, Q. B. Yi, C. Zhengï¼ŒY. Huang, C. K. Li, 
G. Li, X. B. Li, J. Y. Liao, X. Y. Song, S. L. Xiong, C. Z. Liu, 
X. F. Li, Z. W. Li, Z. Chang, A. M. Zhang, Y. F. Zhang, 
X. F. Lu, C. L. Zou (IHEP), Y. J. Jin, Z. Zhang (THU), 
T. P. Li (IHEP/THU), F. J. Lu, L. M. Song, 
M. Wu, Y. P. Xu, S. N. Zhang (IHEP), 
report on behalf of the Insight-HXMT team:

At 2021-01-29T21:48:56.900 (T0), Insight-HXMT/HE detected 
GRB 210129A (trigger ID: HEB210129908) in a routine search of the data, 

The Insight-HXMT/HE light curve mainly consists of a single 
pulse with a duration (T90) of 3.05 s measured from T0+0.04 s. 
The 1-ms peak rate, measured from T0+0.66 s, is 1733 cnts/sec. 
The total counts from this burst is 2481 counts. 
URL_LC: http://twiki.ihep.ac.cn/pub/HXMT/GRBList/HEB210129908_lc.jpg

All measurements above are made with the CsI detectors operating in the 
regular mode with the energy range of about 80-800 keV (deposited energy). 
Only gamma-rays with energy greater than about 200 keV can penetrate 
the spacecraft and leave signals in the CsI detectors installed inside 
of the telescope. 

Insight-HXMT is the first Chinese space X-ray telescope, which was 
funded jointly by the China National Space Administration (CNSA) and 
the Chinese Academy of Sciences (CAS). 
More information about it could be found at: 
http://www.hxmt.org.


GRB_name: GRB210131A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29379
SUBJECT: GRB 210131A: GECAM detection
DATE:    21/02/02 09:48:28 GMT
FROM:    Shuo Xiao at IHEP  <xiaoshuo@ihep.ac.cn>

S. Xiao, C. Cai, S. L. Xiong, Y. Huang, Y. Zhao, C. Y. Li, J. C. Liu,
J. J. He, Q. B. Yi, B. X. Zhang, Y. Q. Zhang, S. Y. Zhao, C. Zheng,
Z. H. An, C. Chen, G. Chen, W. Chen, M. Gao, K. Gong, D. Y. Guo, B. Li,
C. Li, J. H. Li, Q. X. Li, X. B. Li, X. Q. Li, Y. G. Li, X. H. Liang,
J. Y. Liao, J. C. Liu, X. J. Liu, Y. Q. Liu, F. J. Lu, Q. Luo, X. Ma,
G. Ou, W. X. Peng, R. Qiao, D. L. Shi, J. Y. Shi, L. M. Song,
X. Y. Song, G. X. Sun, X. L. Sun, Y. L. Tuo, C. W. Wang, J. Z. Wang,
P. Wang, X. Y. Wen, Y. B. Xu, Y. P. Xu, W. C. Xue, S. Yang, M. Yao,
C. Y. Zhang,D. L. Zhang, Fan Zhang, Fei Zhang, H. M. Zhang, K. Zhang,
P. Zhang, S. N. Zhang, Z. Zhang, X. Y. Zhao, S. J. Zheng, X. Zhou (IHEP),
report on behalf of GECAM team:

During the commissioning phase, the ground search of GECAM-B data found
a long burst, GRB 210131A, at 2021-01-31T12:29:12.000 UTC (T0).

According to the GECAM-B light curves in about 8 keV-4 MeV, this burst
mainly consists of a broad pulse with a duration (T90) of 8.7 +/- 0.4 s.
The 1-s peak counts rate is about 591 cps while the total counts is about
3814 counts.

Although the in-flight calibration of energy response and
localization has not been finalized yet, GECAM-B localized this burst to
the following position (J2000):

Ra: 35.17 deg Dec: 25.23 deg
Err: 7.39 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 light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/utn210131_122912_GECAMb_v0.pdf

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: GRB210202A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29380
SUBJECT: GRB 210202A: Fermi GBM Final Real-time Localization
DATE:    21/02/02 20:20:52 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 LONG GRB

At 20:10:31 UT on 2 Feb 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210202A (trigger 633989436.299376 / 210202841).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 232.2, Dec = -40.4 (J2000 degrees, equivalent to J2000 15h 28m, -40d 23'), with a statistical uncertainty of 1.7 degrees.

The angle from the Fermi LAT boresight is 45.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210202841/quicklook/glg_skymap_all_bn210202841.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/bn210202841/quicklook/glg_healpix_all_bn210202841.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210202841/quicklook/glg_lc_medres34_bn210202841.gif


GRB_name: GRB210202A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29382
SUBJECT: GRB 210202A: BALROG localization (Fermi Trigger  / GRB 210202841)
DATE:    21/02/02 21:25:11 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
 at 20:10:31 on 02 Feb. 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) = 223.5+/-1.5 deg
Decl.(2000.0) = -35.5+/-1.0 deg
We estimate an additional systematic error of 2 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB210202841/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB210202841/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB210202841/json

                        


GRB_name: GRB210202A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29385
SUBJECT: Fermi GRB 210202A: Global MASTER-Net observations report 
DATE:    21/02/03 03:30:15 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-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 210202A ( Fermi GBM team, GCN 29380) errorbox  10111 sec after notice time and 10140 sec after trigger time at 2021-02-02 22:59:31 UT, with upper limit up to  18.0 mag. The observations began at zenith distance = 71 deg. The sun  altitude  is -41.4 deg. 

The galactic latitude b = 13 deg., longitude l = 333 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1538815

We obtain a following upper limits.  

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

   10170 | 2021-02-02 22:59:31 |         MASTER-SAAO | (15h 23m 17.00s , -42d 01m 04.8s) |   C |    60 | 17.7 |        
   10420 | 2021-02-02 23:03:41 |         MASTER-SAAO | (15h 16m 27.32s , -40d 00m 25.3s) |   C |    60 | 18.0 |        
   10505 | 2021-02-02 23:05:06 |         MASTER-SAAO | (15h 37m 27.39s , -40d 00m 36.0s) |   C |    60 | 17.4 |        
   10585 | 2021-02-02 23:06:26 |         MASTER-SAAO | (15h 31m 36.94s , -38d 01m 28.8s) |   C |    60 | 17.7 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB210202A
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29386
SUBJECT: GRB 210202A: Fermi-LAT detection
DATE:    21/02/03 05:58:46 GMT
FROM:    Rachel Hamburg at UAH  <rkh0007@uah.edu>

R. Hamburg (UAH), M. Axelsson (KTH & Stockholm Univ.), M. Arimoto (Kanazawa
Univ.), and R. Pillera (Politecnico and INFN Bari) report on behalf of the
Fermi-LAT team:

On February 2, 2021, Fermi-LAT detected high-energy emission from GRB
210202A, which was also detected by Fermi-GBM (trigger 633989436 /
210202841, GCN 29380).

The best LAT on-ground location is found to be

RA, Dec = 230.0, -38.0 (J2000)

with an error radius of 0.7 deg (90 % containment, statistical error only).

This was 45 deg from the LAT boresight at the time of the GBM trigger:

T0 = 20:10:31.3 UT.

The data from the Fermi-LAT show a significant increase in the event rate
after the GBM trigger that is spatially and temporally correlated with the
GBM emission (3 degrees from the GBM location) with high significance.

The photon flux above 100 MeV in the time interval 0-100s after the GBM
trigger is (2.3 +/- 0.9)e-05 ph/cm2/s, while the flux above 1 GeV is (2.7
+/- 1.6)e-06 ph/cm2/s.

The estimated photon index above 100 MeV is -1.9 +/- 0.3.

The highest-energy photon is a 1.4 GeV event which is observed 19 seconds
after the GBM trigger.

A Swift ToO has been requested for this burst.

The Fermi-LAT point of contact for this burst is Rachel Hamburg (
rkh0007@uah.edu).

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: GRB210202A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29387
SUBJECT: GRB 210202A: Fermi GBM detection
DATE:    21/02/03 16:34:35 GMT
FROM:    Rachel Hamburg at UAH  <rkh0007@uah.edu>

C. Fletcher (USRA), B. Hristov (UAH) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

At 20:10:31.30 UT on 02 February 2021, the Fermi Gamma-Ray Burst Monitor
(GBM)
triggered and located GRB 210202A (trigger 633989436 / 210202841). There
was also
a Fermi/LAT ground detection (R. Hamburg et al., GCN 29386).
The Fermi GBM Final Real-time Localization was reported in GCN 29380.
It is consistent with the Fermi/LAT human-generated position.

The angle from the Fermi LAT boresight at the GBM trigger time is 45
degrees.

The GBM light curve consists of multiple peaks
with a duration (T90) of about 18 s (50-300 keV).
The time-averaged spectrum from T0+0.003 s to T0+18.7 s is
best fit by a power law function with an exponential
high-energy cutoff. The power law index is -0.71 +/- 0.03 and
the cutoff energy, parameterized as Epeak, is 297 +/- 12 keV.
The spectrum is also well fit by a Band function
with Epeak = 265 +/- 16 keV, alpha = -0.66 +/- 0.04,
and beta = -2.5 +/- 0.2.

The event fluence (10-1000 keV) in this time interval is
(1.670 +/- 0.036)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.5 s in the 10-1000 keV band
is 16 +/- 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: GRB210202A
Detection_method: Fermi LAT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29389
SUBJECT: GRB 210202A: AGILE/MCAL detection
DATE:    21/02/03 18:36:16 GMT
FROM:    Alessandro Ursi at INAF/IAPS  <alessandro.ursi@gmail.com>

A. Ursi, M. Cardillo (INAF/IAPS), C. Pittori (SSDC, and INAF/OAR), M.
Tavani (INAF/IAPS, and Univ. Roma Tor Vergata), A. Argan, C. Casentini, Y.
Evangelista, G. Piano (INAF/IAPS), F. Lucarelli, F. Verrecchia (SSDC, and
INAF/OAR), A. Bulgarelli, 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 Mini-CALorimeter (MCAL) detected GRB 210202A at T0 = 2021-02-02
20:10:32.98 +/- 0.01 s (UTC), reported by Fermi/GBM (GCN #29380, #29387)
and Fermi/LAT (GCN #29386).

The event lasted about 2.5 s and released a total number of ~2000 counts in
the detector (in the 0.4-100 MeV energy range), above an average background
rate of 570 Hz.

The light curve shows a single peak and can be found at
http://www.agilescienceapp.it/notices/GRB210202A_AGILE_MCAL.png .

The time-integrated spectrum of the burst can be fitted in the energy range
0.4-10 MeV with a single power-law with ph.ind. = -3.01 -0.52/+0.84,
resulting in a reduced chi-squared of 0.90 (48 d.o.f.) and a fluence of
2.8e-06 ergs/cm^2 (90% confidence level), in the same energy range.

The event is also clearly visible in the scientific ratemeters of the
SuperAGILE (SA; 18-60 keV), MiniCALorimeter (MCAL; 0.4-100 MeV), and
AntiCoincidence (AC; 50-200 keV) detectors. The burst released 340 counts
in the SA detector (above a background rate of 100 Hz), 4580 counts in the
MCAL detector (above a background rate of 1260 Hz), and 12340 counts in the
AC detector (above a background rate of 3700 Hz). The AGILE ratemeters
light curves can be found at:
http://www.agilescienceapp.it/notices/GRB210202A_AGILE_RM.png .

The AGILE-MCAL detector is a CsI detector with a 4 pi FoV, sensitive in the
energy range 0.4-100 MeV. Additional analysis of AGILE data is in progress.
This GRB event did not generate an automatic alert notice. Automatic MCAL
GRB alert Notices can be found at: https://gcn.gsfc.nasa.gov/agile_mcal.html
.


GRB_name: GRB210204A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29390
SUBJECT: GRB 210204A: Fermi GBM Final Real-time Localization
DATE:    21/02/04 06:39:48 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 06:29:25 UT on 4 Feb 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210204A (trigger 634112970.655966 / 210204270).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 109.1, Dec = 9.7 (J2000 degrees, equivalent to J2000 07h 16m, 9d 41'), with a statistical uncertainty of 4.0 degrees.

The angle from the Fermi LAT boresight is 57.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210204270/quicklook/glg_skymap_all_bn210204270.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/bn210204270/quicklook/glg_healpix_all_bn210204270.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210204270/quicklook/glg_lc_medres34_bn210204270.gif


GRB_name: GRB210204A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29391
SUBJECT: GRB 210204A: BALROG localization (Fermi Trigger 634112970 / GRB 210204270)
DATE:    21/02/04 06:59:58 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
634112970 at 06:29:25 on 04 Feb. 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) = 118.6+/-3.1 deg
Decl.(2000.0) = 12.0+/-3.1 deg
We estimate an additional systematic error of 1 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB210204270/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB210204270/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB210204270/json

                        


GRB_name: GRB210204A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29392
SUBJECT: GRB 210204A: GECAM detection
DATE:    21/02/04 07:51:58 GMT
FROM:    Shaolin Xiong at IHEP  <xiongsl@ihep.ac.cn>

C. Y. Li, S. L. Xiong, S. Xiao, C. Cai, Y. Huang, Y. Zhao, J. C. Liu,
J. J. He, Q. B. Yi, B. X. Zhang, Y. Q. Zhang, S. Y. Zhao, C. Zheng,
Z. H. An, C. Chen, G. Chen, W. Chen, M. Gao, K. Gong, D. Y. Guo, B. Li,
C. Li, J. H. Li, Q. X. Li, X. B. Li, X. Q. Li, Y. G. Li, X. H. Liang,
J. Y. Liao, J. C. Liu, X. J. Liu, Y. Q. Liu, F. J. Lu, Q. Luo, X. Ma,
G. Ou, W. X. Peng, R. Qiao, D. L. Shi, J. Y. Shi, L. M. Song,
X. Y. Song, G. X. Sun, X. L. Sun, Y. L. Tuo, C. W. Wang, J. Z. Wang,
P. Wang, X. Y. Wen, Y. B. Xu, Y. P. Xu, W. C. Xue, S. Yang, M. Yao,
C. Y. Zhang,D. L. Zhang, Fan Zhang, Fei Zhang, H. M. Zhang, K. Zhang,
P. Zhang, S. N. Zhang, Z. Zhang, X. Y. Zhao, S. J. Zheng, X. Zhou (IHEP),
report on behalf of GECAM team:

During the commissioning phase, GECAM-B in-flight triggered (Trig#
66119400) a long burst, GRB 210204A, at 2021-02-04T06:30:00.600 UTC (T0),
which was also reported by Fermi/GBM (GCN 29390) and
CALET/CGBM (Trig# 1296455384).

GECAM 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, while the later bright pulse is evident in the alert data
although it falls in the last wide time bin.
The burst spectrum extends above about 400 keV.

An automatic on-ground localization was calculated using the light curves
and spectrum in the alert data.
Although the in-flight calibration of energy response and
localization has not been finalized yet, GECAM-B localized this burst to
the following position (J2000):
Ra: 121.7 deg  Dec: 1.5 deg
Err: 7.5 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-B location is consistent with the Fermi/GBM position (GCN 29390,
29391) within error.

The GECAM light curve could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_lc_grd_all_combine_66119400.png

The GECAM preliminary on-ground location could be found here:
http://twiki.ihep.ac.cn/pub/GECAM/GRBList/gecamb_skymap_bdm_66119400_V01.png

As the detailed science data are downloaded, all analyses would be improved.

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: GRB210204A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29393
SUBJECT: GRB 210204: Fermi GBM observation
DATE:    21/02/04 16:16:59 GMT
FROM:    Elisabetta Bissaldi at INFN,Bari  <elisabetta.bissaldi@ba.infn.it>

E. Bissaldi (Politecnico and INFN Bari)
reports on behalf of the Fermi GBM Team:


"At 06:29:25.66 UT on 4 February 2021, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 210204A (trigger 634112970 / 210204270).
The Fermi GBM Final Real-time Localization was reported in GCN 29390.

The angle from the Fermi LAT boresight at the GBM trigger time is 57 degrees.

The GBM light curve consists of multiple emission episodes
with a duration (T90) of about 210 s (50-300 keV).
The time-averaged spectrum encompassing the first two emission
episodes from T0-8 s to T0+45 s is
adequately fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.51 +/- 0.07 and
the cutoff energy, parameterized as Epeak, is 162 +/- 33 keV.

The event fluence (10-1000 keV) in this time interval is
(5.76 +/- 0.04)E-6 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+201.5 s in the 10-1000 keV band
is 29.3 +/- 0.4 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak = 140 +/- 50 keV, alpha = -1.5 +/- 0.1,
and beta = -2.3 +/- 0.5.


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: GRB210204B
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29394
SUBJECT: GRB 210204B: Fermi GBM Final Real-time Localization
DATE:    21/02/04 18:49:19 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 18:38:59 UT on 4 Feb 2021, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 210204B (trigger 634156744.570034 / 210204777).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 272.5, Dec = -54.8 (J2000 degrees, equivalent to J2000 18h 10m, -54d 47'), with a statistical uncertainty of 2.4 degrees.

The angle from the Fermi LAT boresight is 40.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210204777/quicklook/glg_skymap_all_bn210204777.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/bn210204777/quicklook/glg_healpix_all_bn210204777.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2021/bn210204777/quicklook/glg_lc_medres34_bn210204777.gif


GRB_name: GRB210204A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29395
SUBJECT: Fermi GRB 210204A: Global MASTER-Net observations report 
DATE:    21/02/05 01:45:09 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 210204A ( Fermi GBM team, GCN 29390) errorbox  60315 sec after notice time and 60380 sec after trigger time at 2021-02-04 23:15:45 UT, with upper limit up to  19.5 mag. The observations began at zenith distance = 53 deg. The sun  altitude  is -41.7 deg. 

The galactic latitude b = 10 deg., longitude l = 207 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1539740

We obtain a following upper limits.  

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

   60410 | 2021-02-04 23:15:45 |         MASTER-SAAO | (07h 36m 18.07s , +12d 00m 15.6s) |   C |    60 | 19.5 |        
   60650 | 2021-02-04 23:19:45 |         MASTER-SAAO | (07h 33m 16.34s , +10d 00m 28.3s) |   C |    60 | 19.4 |        
   61528 | 2021-02-04 23:34:23 |         MASTER-SAAO | (07h 36m 15.36s , +12d 02m 18.2s) |   C |    60 | 19.3 |        
   62007 | 2021-02-04 23:42:22 |         MASTER-SAAO | (07h 33m 06.36s , +10d 00m 56.4s) |   C |    60 | 19.4 |        
   62087 | 2021-02-04 23:43:42 |         MASTER-SAAO | (07h 37m 16.25s , +10d 01m 05.7s) |   C |    60 | 19.4 |        
   62845 | 2021-02-04 23:56:20 |         MASTER-SAAO | (07h 36m 14.47s , +12d 01m 44.5s) |   C |    60 | 19.4 |        
   63325 | 2021-02-05 00:04:21 |         MASTER-SAAO | (07h 33m 07.78s , +10d 02m 43.9s) |   C |    60 | 19.4 |        
   63503 | 2021-02-05 00:07:18 |         MASTER-SAAO | (07h 37m 07.26s , +10d 03m 31.2s) |   C |    60 | 19.4 |        
   64498 | 2021-02-05 00:23:53 |         MASTER-SAAO | (07h 37m 02.39s , +10d 02m 11.3s) |   C |    60 | 19.0 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB210204B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29396
SUBJECT: Fermi GRB 210204B: Global MASTER-Net observations report 
DATE:    21/02/05 01:45:22 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-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 210204B ( Fermi GBM team, GCN 29394) errorbox  19603 sec after notice time and 19610 sec after trigger time at 2021-02-05 00:05:50 UT, with upper limit up to  18.1 mag. The observations began at zenith distance = 75 deg. The sun  altitude  is -38.9 deg. 

The galactic latitude b = -17 deg., longitude l = 339 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=1540065

We obtain a following upper limits.  

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

   19640 | 2021-02-05 00:05:50 |         MASTER-SAAO | (18h 03m 24.86s , -58d 03m 48.4s) |   C |    60 | 17.7 |        
   20217 | 2021-02-05 00:15:26 |         MASTER-SAAO | (18h 03m 55.82s , -56d 04m 08.1s) |   C |    60 | 17.8 |        
   20555 | 2021-02-05 00:21:04 |         MASTER-SAAO | (18h 03m 18.65s , -58d 02m 16.0s) |   C |    60 | 17.9 |        
   20635 | 2021-02-05 00:22:24 |         MASTER-SAAO | (18h 10m 58.28s , -58d 03m 18.1s) |   C |    60 | 17.9 |        
   20893 | 2021-02-05 00:26:42 |         MASTER-SAAO | (18h 05m 36.28s , -54d 04m 17.6s) |   C |    60 | 17.7 |        
   21132 | 2021-02-05 00:30:41 |         MASTER-SAAO | (18h 03m 50.26s , -56d 04m 25.2s) |   C |    60 | 17.9 |        
   21211 | 2021-02-05 00:32:00 |         MASTER-SAAO | (18h 11m 05.22s , -56d 04m 25.2s) |   C |    60 | 18.0 |        
   21451 | 2021-02-05 00:36:00 |         MASTER-SAAO | (17h 45m 06.55s , -54d 03m 21.5s) |   C |    60 | 17.8 |        
   21530 | 2021-02-05 00:37:19 |         MASTER-SAAO | (18h 03m 17.60s , -58d 02m 28.3s) |   C |    60 | 17.9 |        
   21610 | 2021-02-05 00:38:39 |         MASTER-SAAO | (18h 10m 56.86s , -58d 03m 34.0s) |   C |    60 | 18.1 |        
   21690 | 2021-02-05 00:39:59 |         MASTER-SAAO | (18h 08m 29.00s , -52d 04m 20.4s) |   C |    60 | 17.7 |        
   21769 | 2021-02-05 00:41:19 |         MASTER-SAAO | (18h 32m 31.40s , -56d 04m 30.4s) |   C |    60 | 17.8 |        
   21849 | 2021-02-05 00:42:38 |         MASTER-SAAO | (18h 05m 39.25s , -54d 02m 48.5s) |   C |    60 | 17.9 |        
   21929 | 2021-02-05 00:43:58 |         MASTER-SAAO | (18h 12m 20.73s , -54d 03m 45.5s) |   C |    60 | 17.9 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB210205A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  29397
SUBJECT: GRB 210205A: Swift detection of a burst
DATE:    21/02/05 11:27:17 GMT
FROM:    Scott Barthelmy at NASA/GSFC  <scott@milkyway.gsfc.nasa.gov>

S. Dichiara (NASA/GSFC/UMCP), E. Ambrosi (INAF-IASFPA),
S. D. Barthelmy (GSFC), V. D'Elia (SSDC), P. A. Evans (U Leicester),
J.D. Gropp (PSU), H. A. Krimm (NSF), N. P. M. Kuin (UCL-MSSL),
A. Y. Lien (GSFC/UMBC) and K. L. Page (U Leicester) report on behalf
of the Neil Gehrels Swift Observatory Team:

At 11:11:17 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 210205A (trigger=1030629).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 347.257, +56.312 which is 
   RA(J2000)  =  23h 09m 02s
   Dec(J2000) = +56d 18' 45"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve shows a multi-peak
structure with a duration of about 35 sec.  The peak count rate
was ~1000 counts/sec (15-350 keV), at ~2 sec after the trigger. 

The XRT began observing the field at 11:13:32.2 UT, 134.7 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source with an enhanced position: RA, Dec 347.2214, 56.2943 which
is equivalent to:
   RA(J2000)  = 23h 08m 53.13s
   Dec(J2000) = +56d 17' 39.4"
with an uncertainty of 2.6 arcseconds (radius, 90% containment). This
location is 95 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 5.15
x 10^21 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 138 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 47% 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 large, but uncertain, extinction expected. 

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/)


