# GCN_circulars

GRB_name: GRB230816A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34473
SUBJECT: GRB 230816A: SVOM/C-GFT optical detection
DATE:    23/08/18 13:41:54 GMT
FROM:    Chao Wu at NAOC <wuchao.lamost@gmail.com>

Liping Xin (NAOC), Chao Wu (NAOC), Zhe Kang (CHO), Xuhui Han (NAOC),  Huali
Li (NAOC), Xiaomeng Lu (NAOC),  Damien Turpin(CEA),  Zhenwei Li
(CHO)ï¼ŒPinpin Zhang (NAOC)ï¼ŒRuosong Zhang (NAOC)ï¼ŒYulei Qiu (NAOC)ï¼ŒYou  Lv
(CHO)ï¼ŒJing Wang(GXU), Cordier Bertrand (CEA)  and Jianyan Wei (NAOC) on
behalf of SVOM GRB team

We observed the burst GRB230816A (Siegel et al. GCN Circ. 34450) on
16:15:38 UT, Aug. 16th, 2023, about 6.9 minutes after the Swift trigger
with C-GFT (Chinese Ground Follow-up Telescope in SVOM mission) in System
Test Mode (STM). C-GFT is located at Jilin (long.=126.33 deg,
lat.=43.8243778 deg), Changchun Observatory, National Astronomical
Observatories, CAS. It has FOV of 1.5 deg X 1.5 deg with a 4k*4k CMOS
detector mounted on the primary focus of  1.2-meter-aperure telescope.

A series of g and r band images were obtained. The exposure time was 10
seconds for each frame.

The optical afterglow reported (Jiang et al.,  GCN 34453, Moskvitin et al.,
GCN 34456., Pankov et al.,GCN 34457, Odeh et al., GCN 34458Klose et al.,
GCN 34459., Kumar et al., GCN 34460; Ruocco et al., GCN 34469) was also
clearly detected by our stacked r-band image (100 * 10 seconds).  The
brightness was estimated to be about 20.1 +/-0.2 magnitude in r-band with
the midtime of about 34 min after the burst, after calibration with nearby
 USNO R2 catalogs.

More detailed analysis is continuing.

We thank the observation assistant Bowen Li at Jilin observatory for their
excellent support.

This message may be cited.


GRB_name: GRB230816A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34474
SUBJECT: GRB 230816A: Swift-BAT refined analysis
DATE:    23/08/18 18:04:02 GMT
FROM:    Tyler Parsotan  at NASA GSFC <tyler.parsotan@nasa.gov>

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


Using the data set from T-239 to T+303 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 230816A (trigger #1185673)
(Siegel, et al., GCN Circ. 34450). The BAT ground-calculated position is
RA, Dec = 328.453, 37.853 deg which is
RA(J2000) = 21h 53m 48.8s
Dec(J2000) = +37d 51' 12.1"
with an uncertainty of 1.2 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 98%.


The mask weighted light curve shows a fast rise exponential decay type single peak.
T90 (15-350 keV) is 20.48 +- 4.94 sec (estimated error including systematics).


The time-averaged spectrum from T-5.60 to T+21.08 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.43 +- 0.14. The fluence in the 15-150 keV band is 7.7 +- 0.7 x 10^-07 erg/cm2.
The 1-sec peak photon flux measured from T+0.60 sec in the 15-150 keV band
is 1.0 +- 0.1 ph/cm2/sec. All the quoted errors are at the 90% confidence
level.


The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1185673/BA/ <http://gcn.gsfc.nasa.gov/notices_s/1185673/BA/>


GRB_name: GRB230812B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34475
SUBJECT: GRB 230812B: SAO RAS observations, possible re-brightening
DATE:    23/08/18 22:28:55 GMT
FROM:    Moskvitin Alexander at SAO RAS <mosk@sao.ru>

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

We observed the field of GRB 230812B (Fermi GBM Team, GCN 34386;
Scotton et al., GCN 34392; Page et al. GCN 34394; Kuin et al.,
GCN 34399; Casentini et al., GCN 34402) with the 1-m telescope
of SAO RAS Zeiss-1000 equipped with the CCD photometer. We obtained
12 x 300 sec. images in Rc band on 20:13:25--21:49:22 UT (August 18).

The OT (Lesage et al., GCN 34387; Scotton et al., GCN 34392; Page,
GCN 34394; Zheng & Filippenko, GCN 34395; Lipunov et al., GCN 34396;
Salgundi et al., GCN 34397; Ackley et al., GCN 34398; Xiong et al.,
GCN 34401; Casentini et al., GCN 34402; Frederiks et al., GCN 34403;
Mao et al., GCN 34404; Odeh et al., GCN 34405; Moskvitin & Spiridonova,
GCN 34406; Leonini et al., GCN 34408; de Ugarte Postigo et al.,
GCNs 24409, 34410; Belkin et al. GCN 34412; Ruocco et al. GCN 34413;
Frederiks et al. GCN 34414; Ruocco et al. GCN 34415; Shrestha et al.
GCN 34416; Quadri et al. GCN 34417; Adami et al. GCN 34418;
Moretti et al. GCN 34419; Kumar et al. GCN 34420; Belkin et al. GCNs
34421, GCN 34423; Pyshna et al., GCN 34425; Moskvitin & Spiridonova,
GCN 34428; Quadri & Strabla, GCN 34430; Mihov et al., GCN 34431;
Belkin et al. GCN 34432; Klose et al., GCN 34435; Scarfi, GCN 34436;
Moskvitin & Spiridonova, GCNs 34442, 34461, 34471; Vinko et al.,
GCN 34463) is clearly detected in our stacked frame with
the brightness of R = 21.46 +/- 0.06 (t_mid - t0 = 6.0856 days).

This preliminary photometry is based on the nearby SDSS stars;
magnitudes are converted using Lupton (2005) equations.


GRB_name: GRB230818A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34478
SUBJECT: GRB 230818A: Fermi GBM Final Real-time Localization
DATE:    23/08/18 23:38:02 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 23:27:35 UT on 18 Aug 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230818A (trigger 714094060.372856 / 230818977).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 289.2, Dec = 41.0 (J2000 degrees, equivalent to J2000 19h 16m, 41d 00'), with a statistical uncertainty of 2.7 degrees.

The angle from the Fermi LAT boresight is 79.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230818977/quicklook/glg_skymap_all_bn230818977.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230818977/quicklook/glg_healpix_all_bn230818977.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230818977/quicklook/glg_lc_medres34_bn230818977.gif


GRB_name: GRB230818A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34479
SUBJECT: GRB 230818A: Swift detection of a burst
DATE:    23/08/18 23:44:09 GMT
FROM:    David Palmer at LANL <palmer@lanl.gov>


A. Tohuvavohu (U Toronto), S. Dichiara (PSU), J.D. Gropp (PSU),
D. M. Palmer (LANL), T. M. Parsotan (GSFC/UMBC/CRESSTII),
B. Sbarufatti (INAF-OAB) and M. A. Williams (PSU) report on behalf of
the Neil Gehrels Swift Observatory Team:

At 23:27:34 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230818A (trigger=1186032).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 285.883, +40.876 which is 
   RA(J2000) = 19h 03m 32s
   Dec(J2000) = +40d 52' 35"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  The BAT light curve showed a single complex
peak structure with a duration of about 10 sec.  The peak count rate
was ~6000 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 23:29:55.4 UT, 141.1 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 285.88966, 40.89504 which is equivalent
to:
   RA(J2000)  = 19h 03m 33.52s
   Dec(J2000) = +40d 53' 42.1"
with an uncertainty of 3.7 arcseconds (radius, 90% containment). This
location is 70 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at https://www.swift.ac.uk/sper.  We
cannot determine whether the source is fading at the present time. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density consistent with the Galactic value of 1.13
x 10^21 cm^-2 (Willingale et al. 2013). 

UVOT took a finding chart exposure of 150 seconds with the White filter
starting 144 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. 
Results from the list of sources generated on-board are not available at this
time. No correction has been made for the expected extinction corresponding to
E(B-V) of 0.101. 

Burst Advocate for this burst is A. Tohuvavohu (aaron.tohu 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: GRB230818A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34480
SUBJECT: GRB 230818A: GOTO optical afterglow detection
DATE:    23/08/19 01:17:17 GMT
FROM:    Ben Gompertz at U of Birmingham <b.gompertz@bham.ac.uk>

B. P. Gompertz, A. Kumar, K. Wiersema, B. Godson, D. Oâ€™Neill, B. Warwick, R. Starling, K. Ackley; M. J. Dyer; J. Lyman; K. Ulaczyk; F. Jimenez-Ibarra; D. Steeghs; D. K. Galloway; V. Dhillon; P. O'Brien; G. Ramsay; K. Noysena; R. Kotak; R. P. Breton; L. K. Nuttall; E. Pall'e and D. Pollacco report on behalf of the GOTO collaboration:

The Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022) observed the field of the X-ray (Tohuvavohu et al., GCN 34479) and optical (Lipunov et al, GCN 34476) counterparts to GRB 230818A (Fermi GBM Team, GCN 34478; Tohuvavohu et al., GCN 34479) at 23:32:00 UT on 2023-08-18, 266 seconds after trigger. The observation consisted of 4x90s exposures in the GOTO L-band (400-700 nm).

Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using recent survey observations of the same pointing. We detect the optical counterpart reported by MASTER (GCN 34476) with a preliminary magnitude of L = 17.75 Â± 0.02 mag.

Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction.

Observations are ongoing.
GOTO (https://goto-observatory.org) is a network of telescopes operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC).


GRB_name: GRB230818A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34482
SUBJECT: Fermi GRB 230818A: Global MASTER-Net observations report
DATE:    23/08/19 01:33:49 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, 
G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov,  D.Cheryasov, Ya.Kechin
(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),

L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez 
(INAOE, Guillermo Haro Astrophysics Observatory),

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

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


MASTER-Tavrida robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started inspect of the Fermi GRB 230818A ( Fermi GBM team, GCN 34478) errorbox  2 sec after notice time and 36 sec after trigger time at 2023-08-18 23:28:11 UT, with upper limit up to  19.1 mag. The observations began at zenith distance = 48 deg. The sun  altitude  is -28.4 deg. 

MASTER-OAFA robotic telescope  located in Argentina (OAFA observatory of San Juan National University) started inspect of the Fermi GRB 230818A errorbox  5 sec after notice time and 38 sec after trigger time at 2023-08-18 23:28:14 UT, with upper limit up to  18.1 mag. The observations began at zenith distance = 79 deg. The sun  altitude  is -17.2 deg. 

MASTER-Kislovodsk robotic telescope  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 230818A errorbox  7 sec after notice time and 40 sec after trigger time at 2023-08-18 23:28:15 UT, with upper limit up to  19.2 mag. The observations began at zenith distance = 54 deg. The sun  altitude  is -26.2 deg. 

The galactic latitude b = 13 deg., longitude l = 73 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2256099

We obtain a following upper limits.  

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

      41 | 2023-08-18 23:28:11 |      MASTER-Tavrida | (19h 04m 27.69s , +40d 41m 46.2s) |   C |    10 | 17.3 |        
      44 | 2023-08-18 23:28:14 |         MASTER-OAFA | (19h 02m 32.62s , +40d 55m 41.9s) |   C |    10 | 15.8 |        
      89 | 2023-08-18 23:28:14 |         MASTER-OAFA | (19h 02m 32.61s , +40d 55m 41.9s) |   C |   100 | 17.1 |  Coadd 
     189 | 2023-08-18 23:28:14 |         MASTER-OAFA | (19h 02m 32.61s , +40d 55m 41.9s) |   C |   300 | 17.6 |  Coadd 
     189 | 2023-08-18 23:28:14 |         MASTER-OAFA | (19h 02m 32.61s , +40d 55m 41.9s) |   C |   300 | 17.6 |  Coadd 
      46 | 2023-08-18 23:28:15 |   MASTER-Kislovodsk | (19h 03m 26.12s , +40d 50m 05.7s) |  P- |    10 | 14.2 |        
      46 | 2023-08-18 23:28:15 |   MASTER-Kislovodsk | (19h 03m 25.92s , +41d 13m 18.9s) |  P| |    10 | 16.4 |        
      56 | 2023-08-18 23:28:15 |   MASTER-Kislovodsk | (19h 03m 25.92s , +41d 13m 18.9s) |  P| |    30 | 17.1 |  Coadd 
     166 | 2023-08-18 23:28:15 |   MASTER-Kislovodsk | (19h 03m 25.91s , +41d 13m 18.9s) |  P| |   250 | 18.5 |  Coadd 
      58 | 2023-08-18 23:28:28 |      MASTER-Tavrida | (19h 04m 22.05s , +40d 40m 49.5s) |   C |    10 | 17.9 |        
      64 | 2023-08-18 23:28:33 |   MASTER-Kislovodsk | (19h 03m 23.93s , +40d 51m 33.7s) |  P- |    10 | 14.2 |        
      64 | 2023-08-18 23:28:33 |   MASTER-Kislovodsk | (19h 03m 23.75s , +41d 14m 47.2s) |  P| |    10 | 16.5 |        
      75 | 2023-08-18 23:28:45 |      MASTER-Tavrida | (19h 04m 22.15s , +40d 41m 48.6s) |   C |    10 | 18.0 |        
      81 | 2023-08-18 23:28:51 |   MASTER-Kislovodsk | (19h 03m 23.92s , +40d 50m 10.0s) |  P- |    10 | 14.5 |        
      82 | 2023-08-18 23:28:51 |   MASTER-Kislovodsk | (19h 03m 23.78s , +41d 13m 23.0s) |  P| |    10 | 16.5 |        
      98 | 2023-08-18 23:29:02 |      MASTER-Tavrida | (19h 04m 27.53s , +40d 40m 46.6s) |   C |    20 | 18.3 |        
      94 | 2023-08-18 23:29:03 |         MASTER-OAFA | (19h 02m 38.15s , +40d 54m 46.1s) |   C |    10 | 15.6 |        
     104 | 2023-08-18 23:29:09 |   MASTER-Kislovodsk | (19h 03m 26.06s , +40d 51m 22.5s) |  P- |    20 | 16.0 |        
     104 | 2023-08-18 23:29:09 |   MASTER-Kislovodsk | (19h 03m 25.95s , +41d 14m 36.8s) |  P| |    20 | 17.2 |        
     129 | 2023-08-18 23:29:09 |   MASTER-Kislovodsk | (19h 03m 25.95s , +41d 14m 36.8s) |  P| |    70 | 17.8 |  Coadd 
     125 | 2023-08-18 23:29:30 |      MASTER-Tavrida | (19h 04m 22.51s , +40d 39m 45.1s) |   C |    20 | 18.3 |        
     133 | 2023-08-18 23:29:38 |   MASTER-Kislovodsk | (19h 03m 20.94s , +40d 50m 50.5s) |  P- |    20 | 16.0 |        
     133 | 2023-08-18 23:29:38 |   MASTER-Kislovodsk | (19h 03m 20.93s , +41d 14m 04.7s) |  P| |    20 | 17.0 |        
     150 | 2023-08-18 23:29:50 |         MASTER-OAFA | (19h 02m 33.15s , +40d 53m 48.4s) |   C |    30 | 16.2 |        
     150 | 2023-08-18 23:29:50 |         MASTER-OAFA | (19h 02m 33.15s , +40d 53m 48.4s) |   C |    30 | 16.2 |        
     158 | 2023-08-18 23:29:57 |      MASTER-Tavrida | (19h 04m 27.91s , +40d 39m 58.3s) |   C |    30 | 18.4 |        
     166 | 2023-08-18 23:30:06 |   MASTER-Kislovodsk | (19h 03m 20.88s , +40d 51m 47.9s) |  P- |    30 | 16.1 |        
     166 | 2023-08-18 23:30:06 |   MASTER-Kislovodsk | (19h 03m 20.92s , +41d 15m 01.9s) |  P| |    30 | 17.5 |        
     200 | 2023-08-18 23:30:35 |      MASTER-Tavrida | (19h 04m 25.14s , +40d 41m 36.2s) |   C |    40 | 18.6 |        
     209 | 2023-08-18 23:30:44 |   MASTER-Kislovodsk | (19h 03m 26.59s , +40d 50m 47.8s) |  P- |    40 | 16.1 |        
     209 | 2023-08-18 23:30:44 |   MASTER-Kislovodsk | (19h 03m 26.71s , +41d 14m 01.5s) |  P| |    40 | 17.7 |        
     264 | 2023-08-18 23:30:44 |   MASTER-Kislovodsk | (19h 03m 26.70s , +41d 14m 01.5s) |  P| |   150 | 18.3 |  Coadd 
     225 | 2023-08-18 23:31:00 |         MASTER-OAFA | (19h 02m 39.38s , +40d 53m 58.2s) |   C |    40 | 16.6 |        
     225 | 2023-08-18 23:31:00 |         MASTER-OAFA | (19h 02m 39.38s , +40d 53m 58.2s) |   C |    40 | 16.6 |        
     252 | 2023-08-18 23:31:22 |      MASTER-Tavrida | (19h 04m 25.14s , +40d 39m 55.8s) |   C |    50 | 18.6 |        
     262 | 2023-08-18 23:31:32 |   MASTER-Kislovodsk | (19h 03m 20.78s , +40d 49m 45.3s) |  P- |    50 | 16.2 |        
     262 | 2023-08-18 23:31:32 |   MASTER-Kislovodsk | (19h 03m 21.04s , +41d 12m 58.3s) |  P| |    50 | 17.8 |        
     289 | 2023-08-18 23:31:59 |         MASTER-OAFA | (19h 02m 35.47s , +40d 55m 39.5s) |   C |    50 | 16.8 |        
     289 | 2023-08-18 23:31:59 |         MASTER-OAFA | (19h 02m 35.47s , +40d 55m 39.5s) |   C |    50 | 16.8 |        
     315 | 2023-08-18 23:32:20 |      MASTER-Tavrida | (19h 04m 28.52s , +40d 41m 33.0s) |   C |    60 | 18.8 |        
     325 | 2023-08-18 23:32:30 |   MASTER-Kislovodsk | (19h 03m 25.74s , +40d 50m 06.7s) |  P- |    60 | 16.2 |        
     325 | 2023-08-18 23:32:30 |   MASTER-Kislovodsk | (19h 03m 26.12s , +41d 13m 19.2s) |  P| |    60 | 17.9 |        
     387 | 2023-08-18 23:33:27 |      MASTER-Tavrida | (19h 04m 22.43s , +40d 40m 31.1s) |   C |    70 | 18.9 |        
     389 | 2023-08-18 23:33:29 |         MASTER-OAFA | (19h 02m 35.66s , +40d 54m 01.9s) |   C |    70 | 16.8 |        
     389 | 2023-08-18 23:33:29 |         MASTER-OAFA | (19h 02m 35.66s , +40d 54m 01.9s) |   C |    70 | 16.8 |        
     398 | 2023-08-18 23:33:38 |   MASTER-Kislovodsk | (19h 04m 24.74s , +41d 13m 15.6s) |  P| |    70 | 12.3 |        
     475 | 2023-08-18 23:34:45 |      MASTER-Tavrida | (19h 04m 21.84s , +40d 41m 27.3s) |   C |    90 | 19.0 |        
     489 | 2023-08-18 23:34:59 |         MASTER-OAFA | (19h 02m 39.29s , +40d 55m 39.9s) |   C |    90 | 17.0 |        
     489 | 2023-08-18 23:34:59 |         MASTER-OAFA | (19h 02m 39.29s , +40d 55m 39.9s) |   C |    90 | 17.0 |        
     534 | 2023-08-18 23:34:59 |         MASTER-OAFA | (19h 02m 39.29s , +40d 55m 39.8s) |   C |   180 | 17.3 |  Coadd 
     585 | 2023-08-18 23:36:24 |      MASTER-Tavrida | (19h 04m 27.65s , +40d 40m 22.8s) |   C |   110 | 19.0 |        
     628 | 2023-08-18 23:37:08 |         MASTER-OAFA | (19h 02m 31.74s , +40d 54m 56.2s) |   C |   110 | 17.2 |        
     628 | 2023-08-18 23:37:08 |         MASTER-OAFA | (19h 02m 31.74s , +40d 54m 56.2s) |   C |   110 | 17.2 |        
     712 | 2023-08-18 23:38:22 |      MASTER-Tavrida | (19h 04m 22.34s , +40d 39m 18.4s) |   C |   130 | 19.0 |        
     773 | 2023-08-18 23:39:18 |         MASTER-OAFA | (19h 02m 32.53s , +40d 55m 57.9s) |   C |   140 | 17.1 |        
     867 | 2023-08-18 23:40:42 |      MASTER-Tavrida | (19h 04m 28.58s , +40d 39m 31.5s) |   C |   160 | 19.1 |        
     967 | 2023-08-18 23:42:17 |         MASTER-OAFA | (19h 02m 38.09s , +40d 54m 58.5s) |   C |   170 | 17.3 |        
    1045 | 2023-08-18 23:43:30 |      MASTER-Tavrida | (19h 04m 25.91s , +40d 41m 04.7s) |   C |   180 | 19.1 |        
    1162 | 2023-08-18 23:45:27 |         MASTER-OAFA | (19h 02m 31.91s , +40d 54m 00.8s) |   C |   180 | 16.8 |        
    1233 | 2023-08-18 23:46:38 |      MASTER-Tavrida | (19h 04m 26.01s , +40d 39m 01.5s) |   C |   180 | 19.1 |        
    1258 | 2023-08-18 23:47:03 |   MASTER-Kislovodsk | (19h 03m 21.94s , +40d 53m 32.1s) |   C |   180 | 16.6 |        
    1258 | 2023-08-18 23:47:03 |   MASTER-Kislovodsk | (19h 03m 26.43s , +41d 17m 09.3s) |   C |   180 | 18.1 |        
    1423 | 2023-08-18 23:49:48 |      MASTER-Tavrida | (19h 04m 29.85s , +40d 40m 44.6s) |   C |   180 | 19.0 |        
    1459 | 2023-08-18 23:50:23 |   MASTER-Kislovodsk | (19h 03m 21.84s , +40d 51m 33.0s) |   C |   180 | 18.1 |        
    1639 | 2023-08-18 23:50:23 |   MASTER-Kislovodsk | (19h 03m 21.84s , +40d 51m 33.0s) |   C |   540 | 18.8 |  Coadd 
    1459 | 2023-08-18 23:50:23 |   MASTER-Kislovodsk | (19h 03m 26.64s , +41d 15m 12.7s) |   C |   180 | 18.5 |        
    1612 | 2023-08-18 23:52:57 |      MASTER-Tavrida | (19h 04m 22.42s , +40d 39m 49.1s) |   C |   180 | 19.1 |        
    1659 | 2023-08-18 23:53:44 |   MASTER-Kislovodsk | (19h 03m 24.49s , +40d 53m 10.0s) |   C |   180 | 18.2 |        
    1659 | 2023-08-18 23:53:44 |   MASTER-Kislovodsk | (19h 03m 29.72s , +41d 16m 49.4s) |   C |   180 | 18.5 |        
    1839 | 2023-08-18 23:53:44 |   MASTER-Kislovodsk | (19h 03m 29.72s , +41d 16m 49.2s) |   C |   540 | 19.2 |  Coadd 
    1802 | 2023-08-18 23:56:06 |      MASTER-Tavrida | (19h 04m 24.04s , +40d 40m 43.5s) |   C |   180 | 19.0 |        
    1991 | 2023-08-18 23:59:16 |      MASTER-Tavrida | (19h 04m 30.28s , +40d 39m 37.6s) |   C |   180 | 19.0 |        
    2066 | 2023-08-19 00:00:31 |   MASTER-Kislovodsk | (19h 03m 19.42s , +40d 53m 01.7s) |   C |   180 | 18.3 |        
    2066 | 2023-08-19 00:00:31 |   MASTER-Kislovodsk | (19h 03m 25.40s , +41d 16m 38.0s) |   C |   180 | 18.6 |        
    2181 | 2023-08-19 00:02:26 |      MASTER-Tavrida | (19h 04m 23.56s , +40d 38m 32.6s) |   C |   180 | 19.0 |        
    2267 | 2023-08-19 00:03:52 |   MASTER-Kislovodsk | (19h 03m 24.05s , +40d 51m 55.1s) |   C |   180 | 18.3 |        
    2447 | 2023-08-19 00:03:52 |   MASTER-Kislovodsk | (19h 03m 24.02s , +40d 51m 55.0s) |   C |   540 | 18.3 |  Coadd 
    2267 | 2023-08-19 00:03:52 |   MASTER-Kislovodsk | (19h 03m 30.34s , +41d 15m 31.0s) |   C |   180 | 18.7 |        
    2371 | 2023-08-19 00:05:36 |      MASTER-Tavrida | (19h 04m 29.48s , +40d 38m 45.7s) |   C |   180 | 19.0 |        
    2553 | 2023-08-19 00:08:38 |   MASTER-Kislovodsk | (19h 03m 26.78s , +40d 51m 59.9s) |  P- |   180 | 17.1 |        
    2553 | 2023-08-19 00:08:38 |   MASTER-Kislovodsk | (19h 03m 33.03s , +41d 15m 28.9s) |  P| |   180 | 18.1 |        
    2733 | 2023-08-19 00:08:38 |   MASTER-Kislovodsk | (19h 03m 33.03s , +41d 15m 28.9s) |  P| |   540 | 18.7 |  Coadd 
    2560 | 2023-08-19 00:08:45 |      MASTER-Tavrida | (19h 04m 27.19s , +40d 40m 02.0s) |   C |   180 | 18.9 |        
    2642 | 2023-08-19 00:10:07 |         MASTER-OAFA | (19h 02m 31.47s , +40d 55m 53.4s) |   C |   180 | 17.6 |        
    2748 | 2023-08-19 00:11:53 |      MASTER-Tavrida | (19h 04m 27.32s , +40d 38m 25.3s) |   C |   180 | 18.9 |        
    2753 | 2023-08-19 00:11:58 |   MASTER-Kislovodsk | (19h 03m 23.68s , +40d 53m 29.5s) |  P- |   180 | 17.2 |        
    2753 | 2023-08-19 00:11:58 |   MASTER-Kislovodsk | (19h 03m 30.38s , +41d 16m 58.6s) |  P| |   180 | 18.2 |        
    2877 | 2023-08-19 00:14:02 |         MASTER-OAFA | (19h 02m 37.86s , +40d 54m 57.1s) |   C |   180 | 17.8 |        
    2936 | 2023-08-19 00:15:01 |      MASTER-Tavrida | (19h 04m 30.09s , +40d 39m 46.5s) |   C |   180 | 18.8 |        
    2954 | 2023-08-19 00:15:19 |   MASTER-Kislovodsk | (19h 03m 23.50s , +40d 51m 43.7s) |  P- |   180 | 17.0 |        
    3134 | 2023-08-19 00:15:19 |   MASTER-Kislovodsk | (19h 03m 23.50s , +40d 51m 43.6s) |  P- |   540 | 17.6 |  Coadd 
    2954 | 2023-08-19 00:15:19 |   MASTER-Kislovodsk | (19h 03m 30.67s , +41d 15m 13.6s) |  P| |   180 | 18.2 |        
    3114 | 2023-08-19 00:17:59 |         MASTER-OAFA | (19h 02m 31.97s , +40d 53m 59.3s) |   C |   180 | 17.9 |        
    3123 | 2023-08-19 00:18:08 |      MASTER-Tavrida | (19h 04m 24.56s , +40d 39m 05.8s) |   C |   180 | 18.8 |        
    3155 | 2023-08-19 00:18:39 |   MASTER-Kislovodsk | (19h 03m 26.10s , +40d 53m 01.5s) |  P- |   180 | 17.1 |        
    3155 | 2023-08-19 00:18:39 |   MASTER-Kislovodsk | (19h 03m 33.83s , +41d 16m 32.2s) |  P| |   180 | 18.1 |        
    3335 | 2023-08-19 00:18:39 |   MASTER-Kislovodsk | (19h 03m 33.83s , +41d 16m 32.3s) |  P| |   540 | 18.6 |  Coadd 
    3311 | 2023-08-19 00:21:15 |      MASTER-Tavrida | (19h 04m 24.82s , +40d 40m 00.4s) |   C |   180 | 18.7 |        
    3355 | 2023-08-19 00:22:00 |   MASTER-Kislovodsk | (19h 03m 19.81s , +40d 52m 23.1s) |  P- |   180 | 17.0 |        
    3355 | 2023-08-19 00:22:00 |   MASTER-Kislovodsk | (19h 03m 28.06s , +41d 15m 54.1s) |  P| |   180 | 18.1 |        
    3498 | 2023-08-19 00:24:23 |      MASTER-Tavrida | (19h 04m 31.83s , +40d 38m 54.8s) |   C |   180 | 18.6 |        
    3516 | 2023-08-19 00:24:41 |         MASTER-OAFA | (19h 02m 34.21s , +40d 55m 52.1s) |   C |   180 | 17.8 |        
    3516 | 2023-08-19 00:24:41 |         MASTER-OAFA | (19h 02m 34.21s , +40d 55m 52.1s) |   C |   180 | 17.8 |        
    3555 | 2023-08-19 00:25:20 |   MASTER-Kislovodsk | (19h 03m 18.96s , +40d 53m 14.5s) |  P- |   180 | 17.0 |        
    3735 | 2023-08-19 00:25:20 |   MASTER-Kislovodsk | (19h 03m 18.96s , +40d 53m 14.5s) |  P- |   540 | 17.5 |  Coadd 
    3555 | 2023-08-19 00:25:20 |   MASTER-Kislovodsk | (19h 03m 27.59s , +41d 16m 45.5s) |  P| |   180 | 18.0 |        
    3686 | 2023-08-19 00:27:31 |      MASTER-Tavrida | (19h 04m 26.57s , +40d 37m 50.4s) |   C |   180 | 18.6 |        
    3715 | 2023-08-19 00:28:00 |         MASTER-OAFA | (19h 02m 34.00s , +40d 54m 26.3s) |   C |   180 | 17.9 |        
    3715 | 2023-08-19 00:28:00 |         MASTER-OAFA | (19h 02m 34.00s , +40d 54m 26.3s) |   C |   180 | 17.9 |        
    3756 | 2023-08-19 00:28:41 |   MASTER-Kislovodsk | (19h 03m 25.70s , +40d 52m 09.0s) |  P- |   180 | 17.0 |        
    3756 | 2023-08-19 00:28:41 |   MASTER-Kislovodsk | (19h 03m 34.73s , +41d 15m 39.4s) |  P| |   180 | 18.0 |        
    3936 | 2023-08-19 00:28:41 |   MASTER-Kislovodsk | (19h 03m 34.73s , +41d 15m 39.4s) |  P| |   540 | 18.5 |  Coadd 
    3877 | 2023-08-19 00:30:42 |      MASTER-Tavrida | (19h 04m 31.80s , +40d 37m 54.0s) |   C |   180 | 18.6 |        
    3956 | 2023-08-19 00:32:01 |   MASTER-Kislovodsk | (19h 03m 19.48s , +40d 51m 00.6s) |  P- |   180 | 17.0 |        
    3956 | 2023-08-19 00:32:01 |   MASTER-Kislovodsk | (19h 03m 28.95s , +41d 14m 31.0s) |  P| |   180 | 18.0 |        
    3989 | 2023-08-19 00:32:33 |         MASTER-OAFA | (19h 02m 36.07s , +40d 55m 58.0s) |   C |   180 | 17.5 |        
    3989 | 2023-08-19 00:32:33 |         MASTER-OAFA | (19h 02m 36.07s , +40d 55m 58.0s) |   C |   180 | 17.5 |        
    4034 | 2023-08-19 00:33:19 |         MASTER-OAFA | (19h 02m 37.30s , +40d 55m 01.6s) |   C |   180 | 17.0 |        
    4034 | 2023-08-19 00:33:19 |         MASTER-OAFA | (19h 02m 37.30s , +40d 55m 01.6s) |   C |   180 | 17.0 |        
    4066 | 2023-08-19 00:33:51 |      MASTER-Tavrida | (19h 04m 28.83s , +40d 39m 32.6s) |   C |   180 | 18.6 |        
    4157 | 2023-08-19 00:35:22 |   MASTER-Kislovodsk | (19h 03m 25.50s , +40d 51m 05.7s) |  P- |   180 | 17.0 |        
    4337 | 2023-08-19 00:35:22 |   MASTER-Kislovodsk | (19h 03m 25.50s , +40d 51m 05.7s) |  P- |   540 | 17.6 |  Coadd 
    4157 | 2023-08-19 00:35:22 |   MASTER-Kislovodsk | (19h 03m 35.40s , +41d 14m 36.0s) |  P| |   180 | 18.0 |        
    4254 | 2023-08-19 00:36:59 |      MASTER-Tavrida | (19h 04m 28.96s , +40d 37m 36.7s) |   C |   180 | 18.6 |        
    4357 | 2023-08-19 00:38:42 |   MASTER-Kislovodsk | (19h 03m 22.52s , +40d 52m 38.1s) |  P- |   180 | 17.0 |        
    4357 | 2023-08-19 00:38:42 |   MASTER-Kislovodsk | (19h 03m 32.76s , +41d 16m 08.7s) |  P| |   180 | 18.0 |        
    4537 | 2023-08-19 00:38:42 |   MASTER-Kislovodsk | (19h 03m 32.76s , +41d 16m 08.7s) |  P| |   540 | 18.6 |  Coadd 
    4441 | 2023-08-19 00:40:06 |      MASTER-Tavrida | (19h 04m 32.13s , +40d 39m 19.8s) |   C |   180 | 18.5 |        
    4558 | 2023-08-19 00:42:03 |   MASTER-Kislovodsk | (19h 03m 22.46s , +40d 51m 03.8s) |  P- |   180 | 17.1 |        
    4558 | 2023-08-19 00:42:03 |   MASTER-Kislovodsk | (19h 03m 33.07s , +41d 14m 34.4s) |  P| |   180 | 18.0 |        
    4629 | 2023-08-19 00:43:14 |      MASTER-Tavrida | (19h 04m 27.31s , +40d 38m 24.6s) |   C |   180 | 18.5 |        
    4662 | 2023-08-19 00:43:47 |         MASTER-OAFA | (19h 02m 35.32s , +40d 55m 01.3s) |   C |   180 | 17.7 |        
    4662 | 2023-08-19 00:43:47 |         MASTER-OAFA | (19h 02m 35.32s , +40d 55m 01.3s) |   C |   180 | 17.7 |        
    4758 | 2023-08-19 00:45:23 |   MASTER-Kislovodsk | (19h 03m 25.24s , +40d 52m 27.5s) |  P- |   180 | 17.0 |        
    4938 | 2023-08-19 00:45:23 |   MASTER-Kislovodsk | (19h 03m 25.24s , +40d 52m 27.5s) |  P- |   540 | 17.5 |  Coadd 
    4758 | 2023-08-19 00:45:23 |   MASTER-Kislovodsk | (19h 03m 36.19s , +41d 15m 58.0s) |  P| |   180 | 18.0 |        
    4820 | 2023-08-19 00:46:25 |      MASTER-Tavrida | (19h 04m 26.18s , +40d 39m 19.5s) |   C |   180 | 18.6 |        
    4947 | 2023-08-19 00:48:32 |         MASTER-OAFA | (19h 02m 35.77s , +40d 54m 19.3s) |   C |   180 | 16.8 |        
    4947 | 2023-08-19 00:48:32 |         MASTER-OAFA | (19h 02m 35.77s , +40d 54m 19.3s) |   C |   180 | 16.8 |        
    4959 | 2023-08-19 00:48:44 |   MASTER-Kislovodsk | (19h 03m 18.30s , +40d 51m 25.8s) |  P- |   180 | 17.0 |        
    4959 | 2023-08-19 00:48:44 |   MASTER-Kislovodsk | (19h 03m 29.69s , +41d 14m 55.6s) |  P| |   180 | 18.0 |        
    5139 | 2023-08-19 00:48:44 |   MASTER-Kislovodsk | (19h 03m 29.69s , +41d 14m 55.6s) |  P| |   540 | 18.4 |  Coadd 
    5007 | 2023-08-19 00:49:32 |      MASTER-Tavrida | (19h 04m 32.82s , +40d 38m 14.5s) |   C |   180 | 18.5 |        
    5195 | 2023-08-19 00:52:39 |      MASTER-Tavrida | (19h 04m 27.62s , +40d 37m 10.2s) |   C |   180 | 18.5 |        
    5360 | 2023-08-19 00:55:25 |   MASTER-Kislovodsk | (19h 03m 24.81s , +40d 51m 11.9s) |  P- |   180 | 16.9 |        
    5360 | 2023-08-19 00:55:25 |   MASTER-Kislovodsk | (19h 03m 36.96s , +41d 14m 41.4s) |  P| |   180 | 17.8 |        
    5385 | 2023-08-19 00:55:50 |      MASTER-Tavrida | (19h 04m 33.92s , +40d 37m 26.2s) |   C |   180 | 18.6 |        
    5560 | 2023-08-19 00:58:45 |   MASTER-Kislovodsk | (19h 03m 17.85s , +40d 50m 03.1s) |  P- |   180 | 17.0 |        
    5740 | 2023-08-19 00:58:45 |   MASTER-Kislovodsk | (19h 03m 17.85s , +40d 50m 03.1s) |  P- |   540 | 17.3 |  Coadd 
    5560 | 2023-08-19 00:58:45 |   MASTER-Kislovodsk | (19h 03m 30.45s , +41d 13m 33.0s) |  P| |   180 | 17.8 |        
    5573 | 2023-08-19 00:58:58 |      MASTER-Tavrida | (19h 04m 30.63s , +40d 38m 50.1s) |   C |   180 | 18.5 |        
    5761 | 2023-08-19 01:02:05 |   MASTER-Kislovodsk | (19h 03m 24.65s , +40d 50m 08.8s) |  P- |   180 | 16.8 |        
    5761 | 2023-08-19 01:02:06 |   MASTER-Kislovodsk | (19h 03m 37.62s , +41d 13m 38.4s) |  P| |   180 | 17.6 |        
    5941 | 2023-08-19 01:02:06 |   MASTER-Kislovodsk | (19h 03m 37.62s , +41d 13m 38.4s) |  P| |   540 | 18.1 |  Coadd 
    5761 | 2023-08-19 01:02:06 |      MASTER-Tavrida | (19h 04m 30.82s , +40d 37m 18.8s) |   C |   180 | 18.5 |        
    5840 | 2023-08-19 01:03:25 |         MASTER-OAFA | (19h 02m 28.43s , +40d 55m 54.7s) |   C |   180 | 17.9 |        
    5840 | 2023-08-19 01:03:25 |         MASTER-OAFA | (19h 02m 28.43s , +40d 55m 54.7s) |   C |   180 | 17.9 |        
    5949 | 2023-08-19 01:05:14 |      MASTER-Tavrida | (19h 04m 34.73s , +40d 38m 37.4s) |   C |   180 | 18.4 |        
    5961 | 2023-08-19 01:05:26 |   MASTER-Kislovodsk | (19h 03m 21.57s , +40d 51m 24.2s) |  P- |   180 | 16.7 |        
    5961 | 2023-08-19 01:05:26 |   MASTER-Kislovodsk | (19h 03m 34.90s , +41d 14m 54.1s) |  P| |   180 | 17.5 |        
    6082 | 2023-08-19 01:07:26 |         MASTER-OAFA | (19h 02m 34.34s , +40d 54m 53.2s) |   C |   180 | 18.0 |        
    6082 | 2023-08-19 01:07:26 |         MASTER-OAFA | (19h 02m 34.34s , +40d 54m 53.2s) |   C |   180 | 18.0 |        
    6139 | 2023-08-19 01:08:24 |      MASTER-Tavrida | (19h 04m 28.83s , +40d 37m 45.8s) |   C |   180 | 18.4 |        
    6162 | 2023-08-19 01:08:47 |   MASTER-Kislovodsk | (19h 03m 35.31s , +41d 13m 27.2s) |  P| |   180 | 17.3 |        
    6162 | 2023-08-19 01:08:47 |   MASTER-Kislovodsk | (19h 03m 21.57s , +40d 49m 57.6s) |  P- |   180 | 16.6 |        
    6301 | 2023-08-19 01:11:06 |         MASTER-OAFA | (19h 02m 28.75s , +40d 53m 52.5s) |   C |   180 | 18.0 |        
    6326 | 2023-08-19 01:11:31 |      MASTER-Tavrida | (19h 04m 29.40s , +40d 38m 41.0s) |   C |   180 | 18.4 |        
    6362 | 2023-08-19 01:12:07 |   MASTER-Kislovodsk | (19h 03m 23.15s , +40d 51m 24.1s) |  P- |   180 | 16.2 |        
    6362 | 2023-08-19 01:12:07 |   MASTER-Kislovodsk | (19h 03m 37.34s , +41d 14m 54.1s) |  P| |   180 | 16.9 |        
    6516 | 2023-08-19 01:14:41 |      MASTER-Tavrida | (19h 04m 35.04s , +40d 37m 36.4s) |   C |   180 | 18.2 |        
    6521 | 2023-08-19 01:14:46 |         MASTER-OAFA | (19h 02m 33.90s , +40d 54m 16.7s) |   C |   180 | 18.1 |        
    6563 | 2023-08-19 01:15:27 |   MASTER-Kislovodsk | (19h 03m 17.09s , +40d 50m 26.2s) |  P- |   180 | 16.0 |        
    6563 | 2023-08-19 01:15:28 |   MASTER-Kislovodsk | (19h 03m 31.77s , +41d 13m 56.3s) |  P| |   180 | 16.5 |        
    6707 | 2023-08-19 01:17:52 |      MASTER-Tavrida | (19h 04m 29.10s , +40d 36m 31.7s) |   C |   180 | 18.2 |        
    6897 | 2023-08-19 01:21:02 |      MASTER-Tavrida | (19h 04m 35.81s , +40d 36m 39.4s) |   C |   180 | 18.1 |        
    7088 | 2023-08-19 01:24:13 |      MASTER-Tavrida | (19h 04m 32.58s , +40d 38m 07.9s) |   C |   180 | 18.1 |        
    7276 | 2023-08-19 01:27:20 |      MASTER-Tavrida | (19h 04m 32.71s , +40d 36m 37.4s) |   C |   180 | 17.9 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB230818A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34483
SUBJECT: GRB 230818A: SAO RAS Zeiss-1000 observations
DATE:    23/08/19 03:12:38 GMT
FROM:    Moskvitin Alexander at SAO RAS <mosk@sao.ru>

A. S. Moskvitin, D. V. Oparin, V. S. Shergin and
V. V. Komarov (SAO RAS), report on behalf of the GRB follow-up team.

We observed the field of GRB 230818A (Fermi GBM team, 34478;
Tohuvavohu et al., GCN 34479) with the 1-m telescope of SAO RAS
Zeiss-1000 equipped with the CCD photometer. We started observations
on August 18, 23:32:18 UT (~5 minutes after the trigger) and obtained
multiple images in BVRcIc bands (principally in Rc).

We clearly detected the OT (Lipunov et al., GCNs 34476, 34477,
34481, 34482; Gompertz et al., GCN 34480) in our individual
frames with the coordinates
R. A. (J2000) = 19:03:33.11
Decl. (J2000) = +40:53:49.2 (+/- 0".5)
and the following brightness:
UT_start   exp, s    t_mid-T0, h   Rmag +/- err
23:32:18    60       0.0872        17.79 +/- 0.06
23:34:00    60       0.1156        18.07 +/- 0.06
23:45:06   120       0.3089        19.18 +/- 0.08
23:57:27   120       0.5147        19.68 +/- 0.10
00:29:01   300       1.0658        20.52 +/- 0.13
00:45:26   2 x 300   1.39333       20.48 +/- 0.09

This preliminary photometry is based on nearby USNO-B1 stars (R2 mag),
the magnitude is not corrected for MW extinction.


GRB_name: GRB230818A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34484
SUBJECT: GRB 230818A: Enhanced Swift-XRT position
DATE:    23/08/19 03:42:13 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.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 1669 s of XRT Photon Counting mode data and 3 UVOT
images for GRB 230818A, 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 = 285.88784, +40.89668 which is equivalent
to:

RA (J2000): 19h 03m 33.08s
Dec (J2000): +40d 53' 48.0"

with an uncertainty of 2.2 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: GRB230818A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34485
SUBJECT: GRB 230818A: NOT photometry and spectroscopy
DATE:    23/08/19 06:20:27 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

D.B. Malesani (Radboud and DAWN/NBI), D. Xu, S.Q. Jiang, T.H. Lu, Z.P. Zhu (NAOC),  J.P.U Fynbo (DAWN/NBI), L. Izzo, (INAF-OACN & DAWN/NBI), Z. Gray (NOT) report:

We observed the optical counterpart (Lipunov et al., GCN 34476; Gompertz et al., GCN 34480) of GRB 230818A detected by Fermi/GBM (Fermi/GBM team, GCN 34478) and Swift/BAT (Tohuvavohu et al., GCN 34479), using the 2.56-m Nordic Optical Telescope (NOT) equipped with the ALFOSC camera.

Observations started at 23:53:33 UT on 2023-08-18, i.e., 26 min post-burst, and 2x1200 s spectra were obtained, with a spectral coverage of 3600 - 9500 AA.

The spectrum shows a trace throughout the whole range, with a broad absorption feature at ~ 4150 AA, which can be interpreted as Lya at z~2.4. Redward several prominent absorption features are present, which can be interpreted as due to Si II, O I, C II, Si IV, C IV, Ni II, Fe II at a common redshift of z = 2.42, being consistent with the Lya feature. We thus think this is the redshift of the burst.

After the spectroscopy, an 150 s exposure in the Sloan i-band was obtained. We measured m(i) = 20.02 +/- 0.02 at 1.21 hr post-burst, calibrated with nearby SDSS stars.


GRB_name: GRB230818A
Detection_method: Swift-UVOT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34486
SUBJECT: GRB 230818A: Swift/UVOT Detection
DATE:    23/08/19 07:46:57 GMT
FROM:    Mike Siegel at PSU/Swift MOC <mhs18@psu.edu>

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

The Swift/UVOT began settled observations of the field of GRB 230818A
144 s after the BAT trigger (Tohuvavohu et al., GCN Circ. 34479).
A source consistent with the optical position (Lipunov et al., GCN
Circ.  34476) is detected in the initial UVOT exposures.

The preliminary UVOT position is:
   RA  (J2000) =  19:03:33.13 = 285.88806 (deg.)
   Dec (J2000) = +40:53:49.0  =  40.89695 (deg.)
with an estimated uncertainty of 0.48 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              144          294          147         19.09 +/- 0.07
v                  379          572           39         18.40 +/- 0.30
b                  477         1513          117         19.68 +/- 0.20
u                  452         1487          117        >19.5
w1                 428         1463           97        >20.2
w2                1026         4987          255        >20.1

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.101 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB230818A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34487
SUBJECT: GRB 230818A: KGO RC-25 optical observations
DATE:    23/08/19 10:06:00 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>

N. Pankov (HSE, IKI)  A. V. Samokhvalov (citizen scientist, Surgut), 
A. Pozanenko (IKI), S. Belkin (IKI, HSE)   report on behalf of GRB IKI FuN:

We observed the field of GRB 230818A (Swift: Tohuvavohu et al., GCN 34479; Fermi:  GBM team, GCN 34478) with 25cm telescope of KGO observatory. Observation started on 2023-08-18 23:42:15, i.e. 14.5 minutes after GRB trigger. The series consist of images with an exposure of 600 s in R-filter. WE clearly detect the afterglow (Lipunov et al., GCN 34476; Gompertz et al., GCN  34480; Moskvitin et al., GCN 34483; Malesani  et al., GCN 34485; Siegel et al., GCN 34486). Preliminary photometry of  images is following

Date UT-start       Exptime Filter t-T0      OT     Err    UL
                    sec            days
2023-08-18 23:42:15 1*600   R      0.013667  18.7   0.2    19.3
2023-08-18 23:52:24 6*600   R      0.038080  19.8   0.3    19.9

Ref.stars
PanSTARRS-DR1
RA Dec r i R(Lupton transformation)
19:03:22.0694 +40:55:31.814 14.1600 14.0074 13.97
19:04:17.2714 +40:50:28.744 14.8986 14.7352 14.71


GRB_name: GRB230818A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34488
SUBJECT: GRB 230818A: Bassano Bresciano Observatory optical observations
DATE:    23/08/19 14:56:53 GMT
FROM:    Ulisse Quadri at Bassano Bresciano Obs <oabb@ulisse.bs.it>

U.Quadri and  L.Strabla (Bassano Bresciano Astronomical Observatory),

Members of: 
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili-GRB.
GAC - Gruppo Astrofili Cremonesi.


We imaged the field of GRB 230818A detected by SWIFT(trigger 1186032)
with the robotic telescope of (IAU station 565) Bassano Bresciano 
Observatory, Italy. 

The observations started 13.61 min after the GRB trigger,  
with our Newton automated telescope D=250 mm F/D=4.8.

Weather conditions were good.

We co-added 3 series of 10 exposures of 60 sec each.

We detected afterglow in the error box of the XRTcandidate.
(Fermi GBM team, GCN 34478; Tohuvavohu et al., GCN 34479; 
Ben Gompertz et al., GCN 34480; V. Lipunov et al. GCN 34482;
A. S. Moskvitin et al., GCN 34483; D.B. Malesani et al., GCN 34485; 
N. Pankov et al., GCN 34487) at the following position (+/- 2 arcsec):

RA (J2000) =  19 03 33.21 
DEC(J2000) = +40 53 49.5


Our photometry of the afterglow are:


Date U.T.            R mag    Sigma
------------------------------------
2023 08 18.99405     18.90    0.07
2023 08 19.00126     19.21    0.07
2023 08 19.00154     19.47    0.06
----------------------------------


COMPARISON STARS
--------------------------------------------------------------------
   pan-STARRS ID          g           r           i         Rc
--------------------------------------------------------------------
157072858562487290     17.4025     16.7800     16.5376     16.56
157052858895609613     16.8323     16.3279     16.1482     16.13
157072859081709765     15.0561     14.7054     14.5820     14.53
157092859169446573     16.9397     16.4745     16.2972     16.28
157102858906415897     17.0217     16.4894     16.2798     16.28
157062859601321798     15.7561     15.2872     15.0934     15.09
--------------------------------------------------------------------

Magnitudes were estimated with the Pan-STARRS cat. 
Rc mag are derived using Lupton (2005) equations.

Not corrected for galactic dust extinction.

Reference:
http://www.osservatoriobassano.org/GRB.asp

The message may be cited.


GRB_name: GRB230818A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34489
SUBJECT: GRB 230818A: Swift-XRT refined Analysis
DATE:    23/08/19 15:19:55 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

S. Dichiara (PSU), J.A. Kennea (PSU), A. Tohuvavohu (U. Toronto), A.P.
Beardmore (U. Leicester), J.P. Osborne (U. Leicester), E. Ambrosi 
(INAF-IASFPA) , M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR)
and P.A. Evans report on behalf of the Swift-XRT team:

We have analysed 6.4 ks of XRT data for GRB 230818A, from 125 s to 40.1
ks after the  BAT trigger. The data comprise 41 s in Windowed Timing
(WT) mode (the first 9 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode. 

The light curve can be modelled with an initial power-law decay with an
index of alpha=2.2 (+0.5, -0.4), followed by a break at T+385 s to an
alpha of 0.76 (+/-0.06).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.96 (+0.21, -0.20). The
best-fitting absorption column is  1.8 (+/-0.7) x 10^21 cm^-2, in
excess of the Galactic value of 1.1 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 3.6 x 10^-11 (4.7 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.8 (+/-0.7) x 10^21 cm^-2
Galactic foreground: 1.1 x 10^21 cm^-2
Excess significance: 1.8 sigma
Photon index:      1.96 (+0.21, -0.20)

If the light curve continues to decay with a power-law decay index of
0.76, the count rate at T+24 hours will be 0.012 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 4.3 x
10^-13 (5.7 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/01186032.

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


GRB_name: GRB230818A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34490
SUBJECT: GRB 230818A: Leavitt Observatory upper limit
DATE:    23/08/19 15:48:22 GMT
FROM:    leavittob@gmail.com

E. Pavoni and L. Moretti (Leavitt Observatory), in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan), 
Y. Niino (Tokyo University, Institute of Astronomy), 
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
report: 

We observed the field of GRB 230818A (Fermi: GBM team, GCN 34478; Swift: Tohuvavohu et al., GCN 34479; Gompertz et al., GCN  34480; Moskvitin et al., GCN 34483; Malesani  et al., GCN 34485; Siegel et al., GCN 34486; Pankov et al., GCN 34487; Quadri et al., GCN 34488) with the telescope of Leavitt Observatory, Italy. Member of: 

UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili, GRB section.
ATA - Associazione Tuscolana di Astronomia.

The observations began at 00:57 UT on 2023/08/18, 90 min after the GRB trigger, with our RC telescope D=250 mm F/D=8.

Weather conditions were good.

We took 32 images of 120 sec each. All images are V filtered, calibrated with master dark and master flat, stacked with ASTAP software.

We have not detected any clearly visible sources, up to 19.60 magnitude with clear sky at 
RA (J2000): 19h 03m 33.08s
Dec (J2000): +40d 53' 48.0"

on a field of view 31.1 x 26.8 arcmin.

Start  End  Vlim
90 min  154 min 19.60

The magnitude limit was estimated with nearby stars from the Gaia EDR3 Catalog and is not corrected for galactic dust extinction.

The message may be cited.  


GRB_name: GRB230818A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34491
SUBJECT: GRB 230818A: Tautenburg observations
DATE:    23/08/19 16:59:54 GMT
FROM:    Sylvio Klose at TLS Tautenburg <klose@tls-tautenburg.de>

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

We observed the field of GRB 230818A (Fermi GBM team, GCN 34478; Tohuvavohu et al., GCN 34479) with the Tautenburg 1.34m Schmidt telescope equipped with the TAUKAM 6kx6k CCD camera and using the Sloan filter set.

For the optical transient discovered by Lipunov et al. (GCN 34476) we measure the following magnitudes:

g = 19.98 +/- 0.02  (midtime: August 19, 2023,  00:03:14 UT),
r = 19.76 +/- 0.02  (midtime: August 19, 2023,  00:14:43 UT),
i = 19.79 +/- 0.03  (midtime: August 19, 2023,  00:26:00 UT),

and

g = 21.35 +/- 0.12  (midtime: August 19, 2023,  01:57:48 UT),
r = 20.97 +/- 0.10  (midtime: August 19, 2023,  02:08:35 UT),
i = 20.86 +/- 0.10  (midtime: August 19, 2023,  02:19:32 UT),

calibrated against the Pan-STARRS catalog.


GRB_name: GRB230818A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34492
SUBJECT: GRB 230818A: AstroSat CZTI detection
DATE:    23/08/19 17:14:33 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

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

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of GRB 230818A which was also detected by Fermi-GBM (Fermi GBM Team, GCN Circ. 34478) and Swift-BAT (Tohuvavohu et al., GCN Circ. 34479).

The source was detected in the 20-200 keV energy range in two quadrants. The light curve peaks at 2023-08-18 23:27:37.5 UTC. The measured peak count rate associated with the burst is 96.6 (+28.4, -24.9) counts/s above the background in the combined data of two quadrants, with a total of 372 (+89, -104) counts. The local mean background count rate was 198.2 (+2.1, -3.3) counts/s. Using cumulative rates, we measure a T90 of 6.3 (+2.1, -1.9) s. 

The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2023-08-18 23:27:37.3 UTC. The measured peak count rate associated with the burst is 356.8 (+79.6, -44.8) counts/s above the background in the combined data of all quadrants, with a total of 2027 (+489, -526) counts. The local mean background count rate was 1569.3 (+11.3, -12.1) counts/s. We measure a T90 of 10.0 (+3.6, -4.3) s from the cumulative Veto light curve.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at: 
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230818A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34493
SUBJECT: GRB 230818A: AKO Upper Limit
DATE:    23/08/19 17:53:39 GMT
FROM:    Mohammad Odeh at Al Khatim Observatory M44 <mshodeh@gmail.com>

Mohammad Odeh, Osama Ghannam, Anas Mohammad, and Khalfan Al-Noaimy, report
on behalf of Al-Khatim Observatory (AKO) operated by the International
Astronomical Center in Abu Dhabi, UAE:

We observed the field of GRB 230818A (Lipunov et al., GCN 34476; Fermi: GBM
team, GCN 34478; Swift: Tohuvavohu et al., GCN 34479; Gompertz et al., GCN
 34480; Moskvitin et al., GCN 34483; Malesani et al., GCN 34485; Siegel et
al., GCN 34486; Pankov et al., GCN 34487; Quadri et al., GCN 34488; Pavoni
et al., GCN 34490; Klose et al., GCN 34491) with our 0.36m f/7.7 robotic
telescope.

We obtained 13 x 180 sec. images in the clear filter on 19 August, from
16:05 to 17:23 UT, (t_mid - t0 = 17.3 hours) with an upper limit of
magnitude = 22.0 for the stacked frames.

We also obtained 15 x 180 sec. images in the Ic filter from 16:02 to 17:32
UT, (t_mid - t0 = 17.35 hours) with an upper limit of magnitude = 20.2 for
the stacked frames.

No reliable optical afterglow object was detected.


GRB_name: GRB230818A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34495
SUBJECT: GRB 230818A: further SAO RAS Zeiss-1000 observations
DATE:    23/08/19 19:35:54 GMT
FROM:    Moskvitin Alexander at SAO RAS <mosk@sao.ru>

A. S. Moskvitin (SAO RAS), V. P. Goranskij (SAI MSU),
report on behalf of the GRB follow-up team.

We observed the field of GRB 230818A (Fermi GBM team, GCN 34478;
Tohuvavohu et al., GCN 34479) with the 1-m telescope of SAO RAS
Zeiss-1000 equipped with the CCD photometer. We obtained
4 x 300 sec. images in Rc band on August 19, 17:42:30--18:07:26 UT.

The OT (Lipunov et al., GCNs 34476, 34477, 34481, 34482;
Gompertz et al., GCN 34480; Moskvitin et al., GCN 34483;
Malesani et al., GCN 34485; Siegel and Tohuvavohu, GCN 34486;
Pankov et al., GCN 34487; Quadri and Strabla, GCN 34488;
Klose et al., GCN 34491) is marginally detected with
the brightness of R = 23.0 +/- 0.3 (t_mid - t0 = 0.76903 days).

This preliminary photometry is based on nearby USNO-B1 stars (R2 mag).
The magnitude of the OT is not corrected for MW extinction.


GRB_name: GRB230812B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34496
SUBJECT: GRB 230812B: SAO RAS Zeiss-1000 observations
DATE:    23/08/19 20:09:24 GMT
FROM:    Moskvitin Alexander at SAO RAS <mosk@sao.ru>

A. S. Moskvitin (SAO RAS), V. P. Goranskij (SAI MSU),
report on behalf of the GRB follow-up team.

We observed the field of GRB 230812B (Fermi GBM Team, GCN 34386;
Scotton et al., GCN 34392; Page et al. GCN 34394; Kuin et al.,
GCN 34399; Casentini et al., GCN 34402) with the 1-m telescope
of SAO RAS Zeiss-1000 equipped with the CCD photometer. We obtained
6 x 300 sec. images in Rc band on August 19, 18:11:41--18:45:30 UT.

The OT (Lesage et al., GCN 34387; Scotton et al., GCN 34392; Page,
GCN 34394; Zheng & Filippenko, GCN 34395; Lipunov et al., GCN 34396;
Salgundi et al., GCN 34397; Ackley et al., GCN 34398; Xiong et al.,
GCN 34401; Casentini et al., GCN 34402; Frederiks et al., GCN 34403;
Mao et al., GCN 34404; Odeh et al., GCN 34405; Moskvitin & Spiridonova,
GCN 34406; Leonini et al., GCN 34408; de Ugarte Postigo et al.,
GCNs 24409, 34410; Belkin et al. GCN 34412; Ruocco et al. GCN 34413;
Frederiks et al. GCN 34414; Ruocco et al. GCN 34415; Shrestha et al.
GCN 34416; Quadri et al. GCN 34417; Adami et al. GCN 34418;
Moretti et al. GCN 34419; Kumar et al. GCN 34420; Belkin et al. GCNs
34421, GCN 34423; Pyshna et al., GCN 34425; Moskvitin & Spiridonova,
GCN 34428; Quadri & Strabla, GCN 34430; Mihov et al., GCN 34431;
Belkin et al. GCN 34432; Klose et al., GCN 34435; Scarfi, GCN 34436;
Moskvitin & Spiridonova, GCNs 34442, 34461, 34471, 34475;
Vinko et al., GCN 34463) is clearly detected in our stacked frame
with the brightness of R = 21.8 +/- 0.1 (t_mid - t0 = 6.9794 days).

This preliminary photometry is based on the nearby SDSS stars;
magnitudes are converted using Lupton (2005) equations.


GRB_name: GRB230818A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34497
SUBJECT: GRB 230818A: SAO RAS 6-m telescope spectroscopy
DATE:    23/08/19 20:52:59 GMT
FROM:    Moskvitin Alexander at SAO RAS <mosk@sao.ru>

A. S. Moskvitin, D. V. Oparin (SAO RAS), A. S. Pozanenko (IKI),
report on behalf of the larger GRB follow-up collaboration.

We observed the GRB 230818A OT (Lipunov et al., GCNs 34476, 34477,
34481, 34482; Gompertz et al., GCN 34480; Moskvitin et al., GCN 34483,
34495; Malesani et al., GCN 34485; Siegel and Tohuvavohu, GCN 34486;
Pankov et al., GCN 34487; Quadri and Strabla, GCN 34488;
Klose et al., GCN 34491) with the BTA 6-meter telescope of SAO RAS
equipped with Scorpio-II. The observations were started since ~ 0.5 h
after the burst (Fermi: GBM team, GCN 34478; Swift: Tohuvavohu et al.,
GCN 34479; AstroSat: Pari et  al., GCN 34492).

In the 4 x 600 sec spectrum of (4200--8530 AA, FWHM resolution ~ 7A)
we identified the absorption lines (C IV, Si II) at a common redshift
of z = 2.42.  We also identified Si IV and Al II lines at a common
redshift of 2.38 which might be an intervening system. Thus we confirm
the redshift measurement obtained by Malezani et al. (GCN 34485).

Using acquisition observation we obtained preliminary photometry
of the afterglow as following (calibrated against Pan-STARRS nearby
stars)

Date        UT-start   Exptime   Filter  t-T0      OT        Err
                       sec               days
2023-08-19  00:00:28   2 x 20     r'     0.02339   19.50 +/- 0.02


GRB_name: GRB230818A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34498
SUBJECT: GRB 230818A: Nickel and KAIT telescope optical observations
DATE:    23/08/19 22:13:43 GMT
FROM:    Weikang Zheng at UC Berkeley <weikang@berkeley.edu>

Neil Pichay, Elma Chuang, WeiKang Zheng and Alex Filippenko (UC Berkeley)

report on behalf of the KAIT GRB team:


We observed the field of GRB 230818A (Fermi GBM team, GCN 34478;

Tohuvavohu et al., GCN 34479) with the 1-m Nickel and 0.76-m KAIT

telescopes located at Lick observatory, California. Observations

started about 0.21 days after the burst. A total of 6 images (600s

exposure each) in R band were taken with Nickel telescopes, while

KAIT images were taken in clear band, with 60s exposure and coadded.

We detected the optical afterglow (Lipunov et al., GCNs 34476, 34477,

34481, 34482; Gompertz et al., GCN 34480; Moskvitin et al., GCN 34483;

Malesani et al., GCN 34485; Siegel and Tohuvavohu, GCN 34486; Pankov

et al., GCN 34487; Quadri and Strabla, GCN 34488; Klose et al., GCN

34491; Moskvitin et al., GCN 34495; 34497) and measure the following

magnitude calibrated to the Pan-STARRS1 catalog:



t-t0(days) filter mag   err

0.218      clear  21.8  0.3

0.226      R      21.6  0.2

0.324      clear  21.3  0.3


GRB_name: GRB230812B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34500
SUBJECT: GRB 230812B: GIT Confirmation of SN rise
DATE:    23/08/20 09:45:51 GMT
FROM:    Vishwajeet Swain at IIT Bombay <vishwajeet.s@iitb.ac.in>

H. Kumar (IITB), V. Swain (IITB), R. Teja (IIA), R. Kumar (IITB), A. Salgundi (IITB), V. Bhalerao (IITB), G.C. Anupama (IIA), D.K. Sahu (IIA), S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team:

We continued observation of the field of the GRB230812B (Fermi GBM Team, GCN 34386) with 0.7m GROWTH-India Telescope (GIT). Starting at 15:26:30 UT on 2023-08-19, we took 18 exposures of 300 sec each in r' band and detected the optical source in our stacked images. We also observed the target with HCT (2x 25 min, PI: R Teja), and detect the source as well. The details of the photometry are given in the below table:


-------------------------------------------------------
JD (mid) | T-T0 (days)| Filter | Exposure (s) | Magnitude (AB) | Telescope

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

2460176.199743 | 6.90 | r' | 18 x 300 | 22.06 +/- 0.10 | GIT

2460176.196935 | 6.91 | r' | 2 x 1500 | 22.04 +/- 0.18 | HCT

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

Our photometry shows a significant deviation from the earlier estimated power-law decay (alpha = 1.23 +/- 0.04) and shows a rise by ~0.9 mag as compared to afterglow-only emission, suggesting the presence of a supernova component. Our results are consistent with A. S. Moskvitin et al., GCN 33475. Based on our SN + PL fits predict that the emission should rise slightly over next 15 days and will start decaying again once the SN peaks around T-T0 ~ 22 days.

We encourage the spectroscopic observation to confirm the presence of SN fully.

Also see: Zheng & Filippenko, GCN 34395, Lipunov et al., GCN 34396, Salgundi et al., GCN 34397, Ackley et al., GCN 34398, Kuin et al. GCN 34399, Mao et al., GCN 34404, Odeh et al., GCN 34405, Moskvitin et al., GCN 34406, Leonini et al., GCN 34408, de Ugarte Postigo et al. GCN 34409, 34410 & 34468, Belkin et al., GCN 34412, and N. Ruocco et al., GCN 34413, N. Ruocco et al., GCN 34413, M. Shrestha et al., GCN 34416, C. Adami et al., GCN 34418, L. Moretti et al., GCN 34419, R. Kumar et al., GCN 33420, S. Belkin et al., GCN 33421, 33423, 33432, O. Pyshna et al., GCN 34425, A. S. Moskvitin et al., GCN 33428, 33442, 33461 33471, 33475 & 33496, U.Quadri and L.Strabla GCN 33430, B. Mihov et al., GCN 33431, Lauren Rhodes et al., GCN 33433, S. Klose et al., GCN  33435, Giulio ScarfÃ¬ et al., GCN 33436, F.D. Romanov GCN 33443, Lopresti et al., GCN 33445, J. Vinko et al., GCN 33463.

The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.


GRB_name: GRB230818A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34501
SUBJECT: GRB 230818A: Fermi GBM Observation
DATE:    23/08/20 18:27:14 GMT
FROM:    Cori Fletcher at USRA <cfletcher@usra.edu>

P. Veres (UAH), C. Fletcher (USRA) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 23:27:35.37 UT on 18 August 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230818A (trigger 714094060/230818977).
which was also detected by Swift-BAT (A. Tohuvavohu et al. 2023, GCN 34479) and AstroSat (B. Pari et al. 2023, GCN 34492).
The Fermi GBM Final Real-time Localization (GCN 34478) is consistent with the Swift-BAT position.

The angle from the Fermi LAT boresight is 79 degrees.

The GBM light curve consists of a couple peaks with a duration (T90)
of about 10 s (50-300 keV). The time-averaged spectrum
from T0-1.5 to T0+13.8 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.02 +/- 0.06 and the cutoff energy,
parameterized as Epeak, is 260 +/- 30 keV.

The event fluence (10-1000 keV) in this time interval is
(5.6 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+0.58 s in the 10-1000 keV band is 10.2 +/- 0.3 ph/s/cm^2.

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

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


GRB_name: GRB230820A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34505
SUBJECT: GRB 230820A: AstroSat CZTI detection
DATE:    23/08/21 08:17:12 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

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

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 230820A which was also detected by Konus Wind (reported through IPN_RAW notices).

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 2023-08-20 11:05:11.65 UTC. The measured peak count rate associated with the burst is 1594 (+233, -173) counts/s above the background in the combined data of all quadrants, with a total of 1625 (+217, -130) counts. The local mean background count rate was 457 (+7, -14) counts/s. Using cumulative rates, we measure a T90 of 4.9 (+0.2, -0.1) s.

The source 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 2023-08-20 11:05:12.25 UTC. The measured peak count rate associated with the burst is 1477 (+88, -95) counts/s above the background in the combined data of all quadrants, with a total of 4814 (+453, -495) counts. The local mean background count rate was 1440 (+7, -8) counts/s. We measure a T90 of 8.5 (+4.0, -3.0) s from the cumulative Veto light curve.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at: 
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230812B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34508
SUBJECT: GRB 230812B : GRANDMA/Kilonova-Catcher optical afterglow detection and upper limits
DATE:    23/08/21 13:15:22 GMT
FROM:    Damien Turpin at CEA-Saclay <dturpin-astro@hotmail.com>

D. Turpin (CEA), M. Serrau (KNC), S. Leonini (KNC), M. Freeberg (KNC), 
F. D. Romanov (KNC), S. Karpov (FZU), S. Antier (OCA/Artemis) report 
on behalf of the GRANDMA/Kilonova-Catcher collaboration:

The Kilonova-Catcher telescope network responded to the alert of 
GRB 230812B (Fermi GBM detection: Roberts et al., GCN 34391;
Fermi LAT detection: Scotton et al., GCN 34392). 

The KNC observations were taken by M. Serrau at the Chante-Perdrix 
Observatory (France), S. Leonini at the Montarrenti Observatory (Italy),
M. Freeberg at the Hidden Valley Observatory (USA) and F.~D. Romanov at the
iTelescope.Net in Sierra Remote Observatory (USA).
The afterglow is first detected in 50x30s R-band coadded images at
about 1 day (midtime of the exposure) after the Fermi/GBM trigger time.

Below, we report a subset of our photometric measurements.
---------------------------------------------------------------------------------
T-T0 (midtime,day)  |Exposure| Filter | Mag +/- err |Mag.Lim. (5sig AB) |Observer
---------------------------------------------------------------------------------
1.024 | 50 x 30s | Rc | 20.35 +/- 0.16 | -- | Leonini
1.164 | 15 x 180s | V | 20.74 +/- 0.08 | -- | Serrau
1.182 | 30 x 180s | Rc | 20.87 +/- 0.15 | -- | Serrau
1.425 | 6 x 300s | Ic | -- | 18.6 | Romanov
2.334 | 12 x 300s | r | -- | 20.6 | Freeberg
2.397 | 12 x 300s | i | -- | 19.3 | Freeberg
2.624 | 30 x 180s | Rc | 21.29 +/- 0.11 | -- | Serrau
4.080 | 40 x 180s | V | 22.20 +/- 0.21 | -- | Serrau

Our detections are consistent with the fading behavior previously reported
by GRANDMA Mao et al., GCN 34404; Pyshna et al., GCN 34425. We note that
the underlying host galaxy may contribute to our late photometric 
measurements. The reported magnitudes are not corrected for the galactic
dust extinction in the line of sight of the burst. 

The GRANDMA/Kilonova-Cacther images have been calibrated using field
stars from the PanSTARRS-DR1 catalog using the STDpipe pipeline
(Karpov 2022) and the ps1/r to Rc mag conversion from (Pancino et al. 2022).

GRANDMA is a worldwide telescope network (grandma.ijclab.in2p3.fr)
devoted to the observation of transients in the context of multi-messenger
astrophysics (Antier et al. 2020 MNRAS 497, 5518). Kilonova-Catcher (KNC) is
the citizen science program of GRANDMA (http://kilonovacatcher.in2p3.fr/).


GRB_name: GRB230818A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34511
SUBJECT: Konus-Wind detection of GRB 230818A
DATE:    23/08/21 15:16:55 GMT
FROM:    Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>

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

The long GRB 230818A (Swift detection: Tohuvavohu et al., GCN 34479;
Fermi GBM observation: Veres et al., GCN 34501)
triggered Konus-Wind (KW) at T0=84458.443 s UT (23:27:38.443).

The burst light curve shows a single FRED-like pulse
which starts at ~T0-0.256 s and has a duration of ~10 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/GRB230818_T84458/

As observed by Konus-Wind, the burst had
a total fluence of (4.91 Â± 1.76)x10^-6 erg/cm^2 and
a 64-ms peak energy flux, measured from T0,
of (3.08 Â± 0.90)x10^-6 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum of the burst (measured from T0 to T0+16.640 s)
is best fit in the 20 keV - 15 MeV range by a power law with exponential
cutoff (CPL) model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -1.00(-0.23,+0.27) and Ep = 251(-49,+81) keV (chi2 = 91/98 dof).
Fitting this spectrum by a Band function yields the same values of alpha and Ep,
and an upper limit on the high energy photon index beta of -2.5 (chi2 = 91/97 dof).

The spectrum near the peak count rate (measured from T0 to T0+0.256 s)
is best fit in the 20 keV - 15 MeV range by a CPL model
with alpha = -0.40(-0.44,+0.56) and Ep = 259(-45,+64) keV (chi2 = 18/17 dof).
Fitting this spectrum by a Band function yields the same values of alpha and Ep,
and an upper limit on the high energy photon index beta of -2.7 (chi2 = 18/16 dof).

Assuming the redshift z=2.42 (Malesani et al., GCN 34485)
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 burst isotropic energy release E_iso to (6.95 Â± 2.49)x10^52 erg,
the isotropic peak luminosity L_iso to (1.49 Â± 0.44)x10^53 erg/s,
the rest-frame peak energy of the time-integrated spectrum Ep,i,z to ~860 keV,
and the rest-frame peak energy at the peak of the emission Ep,p,z to ~890 keV.
With the obtained estimates, GRB 230818A is inside 90% prediction band for
the 'Amati' relation and inside 68% prediction band for the 'Yonetoku' relation
derived for the sample of >300 long KW GRBs with known redshifts
(Tsvetkova et al., 2017; Tsvetkova et al., 2021), see
http://www.ioffe.ru/LEA/GRBs/GRB230818_T84458/GRB230818A_rest_frame.pdf

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


GRB_name: GRB230818A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34514
SUBJECT: GRB 20230818A: GIT optical upper limit
DATE:    23/08/21 16:35:40 GMT
FROM:    Varun Bhalerao at IIT Bombay <varunb@iitb.ac.in>

R. Kumar (IITB), A. Salgundi (IITB), V. Swain (IITB), H. Kumar (IITB), V. Bhalerao (IITB), G.C. Anupama (IIA), S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team:

We observed the field of GRB230818A (Lipunov et al., GCN 34476; Fermi GBM team, GCN 34478; Tohuvavohu et al., GCN 34479; Gompertz et al., GCN  34480; Moskvitin et al., GCN 34483; Malesani et al., GCN 34485; Siegel et al., GCN 34486; Pankov et al., GCN 34487; Quadri et al., GCN 34488; Pavoni et al., GCN 34490; Klose et al., GCN 34491; Pari et al., GCN 34492; Odeh et al., GCN 34493; Pichay et al., GCN 34498) with the 0.7m GROWTH-India Telescope (GIT). The observations started at 2023-08-19 15:32:24.081 UT, 0.67 days after the Fermi GBM trigger. We obtained 6 images of 300-sec exposures in the r' filter. We did not detect any new source in our stacked image around R.A.= 19h 03m 33.11s, DEC.=+40d 53m 48.5s. The obtained upper limits follow as:

-------------------------------------------------------
JD (mid) | T-T0 (hours) | Filter | Exposure (s) | Limiting Magnitude (AB)
-------------------------------------------------------
2460176.15764106 | 16.326 | r' | 6 x 300 | 21.35
-------------------------------------------------------

Our results are consistent with the upper limits reported by AKO (Odeh et al., GCN 34493) and the weak detection by SAO RAS Zeiss-1000 (Moskvitin et al., GCN 34495). The magnitudes are calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.

The GROWTH India Telescope (GIT, Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.


GRB_name: GRB230818A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34515
SUBJECT: GRB 230818A: Swift-BAT refined analysis
DATE:    23/08/21 19:26:51 GMT
FROM:    Tyler Parsotan  at NASA GSFC <tyler.parsotan@nasa.gov>

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


Using the data set from T-60 to T+200 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 230818A (trigger #1186032)
(Tohuvavohu, et al., GCN Circ. 34479). The BAT ground-calculated position is
RA, Dec = 285.888, 40.888 deg which is
RA(J2000) = 19h 03m 33.2s
Dec(J2000) = +40d 53' 16.5"
with an uncertainty of 1.1 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 32%.


The mask weighted light curve shows a single fast rise exponential decay peak.
T90 (15-350 keV) is 9.82 +- 1.25 sec (estimated error including systematics).


The time-averaged spectrum from T+0.07 to T+12.10 sec is best fit by a simple
power-law model. The power law index of the time-averaged spectrum is
1.36 +- 0.10. The fluence in the 15-150 keV band is 1.9 +- 0.1 x 10^-06 erg/cm2.
The 1-sec peak photon flux measured from T+1.59 sec in the 15-150 keV band
is 6.7 +- 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/1186032/BA/ <http://gcn.gsfc.nasa.gov/notices_s/1186032/BA/>


GRB_name: GRB230812B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34516
SUBJECT: GRB 230812B: SAO RAS RC-500 and Zeiss-1000 observations
DATE:    23/08/21 19:58:42 GMT
FROM:    Moskvitin Alexander at SAO RAS <mosk@sao.ru>

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

We observed the field of GRB 230812B (Fermi GBM Team, GCN 34386;
Scotton et al., GCN 34392; Page et al. GCN 34394; Kuin et al.,
GCN 34399; Casentini et al., GCN 34402) with the SAO RAS optical
telescopes RC-500 and Zeiss-1000 equipped with the CCD photometers.
We obtained 90 x 60 sec. images in Rc band with the 0.5-m telescope
on August 20, 18:36:51--20:27:56 and 6 x 300 sec. images in Rc band
with the 1-m telescope on August 20, 21:09:05--21:43:00 UT.

The OT (Lesage et al., GCN 34387; Scotton et al., GCN 34392; Page,
GCN 34394; Zheng & Filippenko, GCN 34395; Lipunov et al., GCN 34396;
Salgundi et al., GCN 34397; Ackley et al., GCN 34398; Xiong et al.,
GCN 34401; Casentini et al., GCN 34402; Frederiks et al., GCN 34403;
Mao et al., GCN 34404; Odeh et al., GCN 34405; Moskvitin & Spiridonova,
GCN 34406; Leonini et al., GCN 34408; de Ugarte Postigo et al.,
GCNs 24409, 34410; Belkin et al. GCN 34412; Ruocco et al. GCN 34413;
Frederiks et al. GCN 34414; Ruocco et al. GCN 34415; Shrestha et al.
GCN 34416; Quadri et al. GCN 34417; Adami et al. GCN 34418;
Moretti et al. GCN 34419; Kumar et al. GCN 34420; Belkin et al. GCNs
34421, GCN 34423; Pyshna et al., GCN 34425; Moskvitin & Spiridonova,
GCN 34428; Quadri & Strabla, GCN 34430; Mihov et al., GCN 34431;
Belkin et al. GCN 34432; Klose et al., GCN 34435; Scarfi, GCN 34436;
Moskvitin & Spiridonova, GCNs 34442, 34461, 34471, 34475;
Vinko et al., GCN 34463; H. Kumar et al., GCN 34500; Turpin et al.,
GCN 34508) is clearly detected in our stacked frames
with the brightness of R = 21.58 +/- 0.11 (t_mid - t0 = 8.0237 days)
and R = 21.44 +/- 0.07 (t_mid - t0 = 8.1027 days).

This preliminary photometry is based on the nearby SDSS stars;
magnitudes are converted using Lupton (2005) equations.


GRB_name: GRB230815A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34518
SUBJECT: GRB 230815A: ATCA detection of radio counterpart
DATE:    23/08/22 11:44:32 GMT
FROM:    James Leung at U of Sydney/VAST <jleu9465@uni.sydney.edu.au>

J. K. Leung (USyd), G. E. Anderson (Curtin), S. D. Ryder (Macquarie),
A. J. van der Horst (GWU), A. Gulati (USyd), L. Rhodes (Oxford), 
S. Chastain (UNM) on behalf of the PanRadio GRB collaboration

The Australia Telescope Compact Array (ATCA) observed long GRB 230815A 
(Klingler et al., GCN 34434; Mailyan et al., GCN 34440) as part of the 
ATCA "PanRadio GRB" follow-up Large Project C3542 (PI. Anderson) on 
2023-08-17 UT and 2023-08-18 UT. 

No radio sources were detected at the GRB location in the first 
observation conducted from 2023-08-17 02:00 UT for 10 hrs at 5.5, 9.0, 
16.7 and 21.2 GHz. The 3-sigma upper limits were 75, 69, 324, 741 
microJy/beam, respectively. Note the higher than usual rms was due to 
bad weather during the observation.

The second observation was conducted from 2023-08-18 22:00 UT for 6 hrs 
at 5.5, 9.0 and 44 GHz. In our preliminary analysis, we detect a radio 
counterpart with a flux density of 70+/-10 microJy at 9 GHz. The fitted 
position is:

RAJ2000  = 12:18:53.2
DECJ2000 = -58:03:09.0
with an uncertainty of ~0.3". 

This is in broad agreement with previously reported Swift/XRT (Beardmore
et al., GCN 34437) and VLT/HAWK-I (Schneider et al., GCN 34467) 
afterglow positions. There was also a marginal ~3 sigma detection at 
5.5 GHz (rms=14 microJy/beam) and a non-detection at 44 GHz with a
3-sigma upper limit of 111 microJy/beam.

Further observations are planned.

We thank the CSIRO Space and Astronomy staff for supporting these 
observations. We acknowledge the Gomeroi people as the traditional
owners of the Observatory site. The Australia Telescope Compact Array is
part of the Australia Telescope National Facility 
(https://ror.org/05qajvd42) which is funded by the Australian Government
for operation as a National Facility managed by CSIRO.


GRB_name: GRB230812B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34519
SUBJECT: GRB 230812B: Assy  optical observations, possible SN rise
DATE:    23/08/22 11:49:56 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>

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

We observed the field of GRB 230812B (Fermi GBM Team, GCN 34386;
Scotton et al., GCN 34392; Page et al. GCN 34394; Kuin et al.,
GCN 34399; Casentini et al., GCN 34402) with AZT-20 telescope of Assy-Turgen observatory  on 2023-08-17 -- 2023-08-21.

The OT (Lesage et al., GCN 34387; Scotton et al., GCN 34392; Page,
GCN 34394; Zheng & Filippenko, GCN 34395; Lipunov et al., GCN 34396;
Salgundi et al., GCN 34397; Ackley et al., GCN 34398; Xiong et al.,
GCN 34401; Casentini et al., GCN 34402; Frederiks et al., GCN 34403;
Mao et al., GCN 34404; Odeh et al., GCN 34405; Moskvitin & Spiridonova,
GCN 34406; Leonini et al., GCN 34408; de Ugarte Postigo et al.,
GCNs 24409, 34410; Belkin et al. GCN 34412; Ruocco et al. GCN 34413;
Frederiks et al. GCN 34414; Ruocco et al. GCN 34415; Shrestha et al.
GCN 34416; Quadri et al. GCN 34417; Adami et al. GCN 34418;
Moretti et al. GCN 34419; Kumar et al. GCN 34420; Belkin et al. GCNs
34421, GCN 34423; Pyshna et al., GCN 34425; Moskvitin & Spiridonova,
GCN 34428; Quadri & Strabla, GCN 34430; Mihov et al., GCN 34431;
Belkin et al. GCN 34432; Klose et al., GCN 34435; Scarfi, GCN 34436;
Moskvitin & Spiridonova, GCNs 34442, 34461, 34471, 34475;
Vinko et al., GCN 34463; H. Kumar et al., GCN 34500; Turpin et al.,
GCN 34508) is clearly detected.

Preliminary photometry of the OT is following

Telescope Date UTstart Exptime Filter t-T0 OT Err UL
                       sec            days
AZT-20 2023-08-17 16:51:34 60x60 r 4.932892 21.70 0.05 23.9
AZT-20 2023-08-17 18:14:50 60x60 i 4.990722 21.87 0.10 23.2
AZT-20 2023-08-18 16:47:02 60x60 r 5.929748 21.71 0.07 23.8
AZT-20 2023-08-18 18:05:43 60x60 i 5.984388 21.73 0.10 23.2
AZT-20 2023-08-20 16:15:33 60x60 r 7.907882 21.70 0.04 24.1
AZT-20 2023-08-20 17:37:12 60x60 i 7.964583 21.82 0.09 23.3
AZT-20 2023-08-21 16:31:06 60x60 r 8.918678 21.61 0.05 23.3
AZT-20 2023-08-21 17:51:59 80x60 i 8.981796 21.39 0.06 23.4

The photometry is based on nearby SDSS stars.
SDSS-DR12
RA Dec r i
16:36:25.6 +47:53:20.5 17.018 16.857
16:36:25.2 +47:52:20.9 16.229 16.106

After plateau phase between Aug. 15 - Aug.20  at r ~ 21.7, i~ 21.8 which is brighter than a host galaxy (e.g. Legacy Survey DR10 Catalog the host is r~22.66 (Belkin et al., GCN 34412)) the OT is brightening and we can confirm  the OT  brightening (Moskvitin et al., GCN 34516) which   could be related with a supernova rise. The supernova rise have beed also suggested by GIT (GCN 34500).


GRB_name: GRB230822A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34521
SUBJECT: GRB 230822A: Fermi GBM Final Real-time Localization
DATE:    23/08/22 23:59:33 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 23:48:54 UT on 22 Aug 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230822A (trigger 714440939.403512 / 230822992).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 143.4, Dec = 38.0 (J2000 degrees, equivalent to J2000 09h 33m, 38d 00'), with a statistical uncertainty of 18.4 degrees.

The angle from the Fermi LAT boresight is 78.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230822992/quicklook/glg_skymap_all_bn230822992.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230822992/quicklook/glg_healpix_all_bn230822992.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230822992/quicklook/glg_lc_medres34_bn230822992.gif


GRB_name: GRB230818A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34523
SUBJECT: GRID detection of GRB 230818A
DATE:    23/08/23 02:35:17 GMT
FROM:    GRID Student Team at Tsinghua University <grid@tsinghua.edu.cn>

Chenyu Wang and Zirui Yang report on behalf of the GRID Collaboration:

The long-duration GRB 230818A (Fermi/GBM detection: GCN Circular 34478 and Swift/BAT detection: GCN Circular 34479 ) was observed with GRID-03B.

The detection was confirmed at the trigger time 2023-08-18T23:27:30 UTC. The measured burst duration (T90) in the 30-2000 keV range is approximately 8.75 Â± 1.63 seconds..

GRID is a student-led project to monitor the transient gamma-ray sky with multiple detectors onboard different nanosatellites in the era of multi-messenger astronomy. For more information about GRID, please refer to the following references: https://doi.org/10.1007/s10686-019-09636-w and https://doi.org/10.1007/s10686-021-09819-4.


GRB_name: GRB230818B
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34524
SUBJECT: GRB 230818B: AstroSat CZTI detection
DATE:    23/08/23 08:30:35 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

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

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 230818B which was also detected by Konus-Wind (reported in GCN notices).

The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2023-08-18 10:12:55.5 UTC. The measured peak count rate associated with the burst is 139 (+41, -20) counts/s above the background in the combined data of all quadrants, with a total of 1336 (+411, -462) counts. The local mean background count rate was 423 (+3, -4) counts/s. Using cumulative rates, we measure a T90 of 20 (+8, -6) s. 

The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2023-08-18 10:12:54.3 UTC. The measured peak count rate associated with the burst is 379 (+74, -41) counts/s above the background in the combined data of all quadrants, with a total of 4772 (+696, -879) counts. The local mean background count rate was 1568 (+7, -8) counts/s. We measure a T90 of 26 (+2, -5) s from the cumulative Veto light curve.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at: 
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230818B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34525
SUBJECT: GRB 230818B: VZLUSAT-2 detection
DATE:    23/08/23 12:08:03 GMT
FROM:    Marianna DafÄÃ­kovÃ¡ at Masaryk University <500025@mail.muni.cz>

M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory),  N. Werner  (Masaryk U.), M. Ohno (Hiroshima U.),  L. Meszaros, B. Csak (Konkoly Observatory), H. Takahashi (Hiroshima U.), F. Munz , M. Topinka, F. Hroch, N. Husarikova, J.-P. Breuer (Masaryk U.), J. Hudec, J. Kapus, M. Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo (Needronix), G. Galgoczi (Wigner Research Center/Eotvos U.), N. Uchida (ISAS/JAXA), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. Hirose, H. Matake (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), K. Torigoe (Hiroshima U.), P. Svoboda, V. Daniel, J. Dudas, M. Junas, J. Gromes (VZLU), I. Vertat (FEL ZCU)  -- the VZLUSAT-2/GRB payload collaboration.

The long duration GRB 230818B (AstroSat detection: GCN 34524; Konus/Wind detection at 2023-08-18 10:12:54.913 UT) was detected by the GRB detectors on board of the VZLUSAT-2 3U CubeSat (https://www.vzlusat2.cz/en/).

The data acquisition was performed by the GRB detector units no. 0 and no. 1. The detection was confirmed at the peak time 2023-08-18 10:12:53 (10:13:04) UTC. The T90 duration is 29 s (29 s) and the significance during T90 reaches 14 sigma (12 sigma) for detector unit no. 0 (no. 1).

The light curve obtained by VZLUSAT-2 is available here:
https://vzlusat2.konkoly.hu/static/share/GRB230818B_GCN_VZLUSAT2.pdf

All VZLUSAT-2 detections are listed at: https://monoceros.physics.muni.cz/hea/VZLUSAT-2/
The GRB detectors on VZLUSAT-2 are a demonstration payload for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). Two GRB modules of VZLUSAT-2 are placed in a perpendicular manner and each consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~30 keV to ~1000 keV. VZLUSAT-2 was launched on 2022 January 13 from Cape Canaveral.


GRB_name: GRB230812B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34526
SUBJECT: GRB 230812B: AstroSat LAXPC detection
DATE:    23/08/23 13:46:50 GMT
FROM:    Tilak Katoch at TIFR <tilak@tifr.res.in>

Tilak Katoch, H. M. Antia and Parag Shah TIFR, Mumbai, India.

AstroSat LAXPC data analysis revealed the presence of a strong short GRB 230812B. The GRB burst profile shows that it was triggered at T0 = 18h 58m 08s UT on 12 Aug 2023, when the satellite was in a normal operating mode and well before and after the SAA region.

The lightcurve obtained a burst profile with T90 = 4 sec. The strongest peak measured have a count rate 10678 +/- 105 count/sec in LAXPC10 above the background and 5069 +/- 73 count/sec in LAXPC20 at T0+2 sec.

Both LAXPC instruments (LAXPC10 and LAXPC20) have registered this burst profile in their respective lightcurves. LAXPC20 has a nominal energy range of 3-100 keV, but due to the lower gain in LAXPC10, the energy range is approximately 30-400 keV.

The background subtracted lightcurves of the LAXPC instruments with 0.2 sec time-bin is available at the website:

https://www.tifr.res.in/~astrosat_laxpc/grb230812lc.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: GRB230822A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34529
SUBJECT: GRB 230822A: Swift/BAT-GUANO detection of a burst
DATE:    23/08/23 20:26:06 GMT
FROM:    Jimmy DeLaunay at University of Alabama  <delauj2@gmail.com>

James DeLaunay (UAlabama), Gayathri Raman (PSU), Samuele Ronchini (PSU), Aaron Tohuvavohu (U Toronto), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report:

Swift/BAT did not localize GRB 230822A onboard (T0: 2023-08-22T23:48:54.40 UTC, Fermi GBM Trig 714440939, GCN 34521). 

The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). 

Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground.

The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), detects the burst with a sqrt(TS) of 9.7 in a 1.024 s analysis time bin, starting at T0 - 1.792 s.

NITRATES results, independently, are ambiguous with respect to whether this burst originates from in or outside the BAT coded FOV, with a DeltaLLHOut of 7.7.

See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut.

GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.

A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/


GRB_name: GRB230822A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34531
SUBJECT: GRB 230822A: Fermi GBM Observation
DATE:    23/08/24 01:40:05 GMT
FROM:    Stephen Lesage at Fermi-GBM Team <sjl0014@uah.edu>

S. Lesage (UAH) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 23:48:54 UT on 22 August 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230822A (trigger 714440939/230822992).
which was also detected by Swift/BAT-GUANO (DeLaunay et al. 2023, GCN 34529).
The Fermi GBM Final Real-Time Localization was reported previously (Fermi GBM Team 2023, GCN 34521).

The angle from the Fermi LAT boresight is 78 degrees.

The GBM light curve consists of a single weak emission episode with a duration (T90)
of about 0.9 s (50-300 keV). The time-averaged spectrum
from T0-0.448 to T0 s is best fit by
a simple power law function with index -1.3 +/- 0.2.

The event fluence (10-1000 keV) in this time interval is
(5.7 +/- 2.6)E-08 erg/cm^2. The 64-ms peak photon flux measured
starting from T0-1.7 s in the 10-1000 keV band is 2.2 +/- 0.9 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: GRB230824A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34537
SUBJECT: GRB 230824A: Swift detection of a burst
DATE:    23/08/24 14:12:46 GMT
FROM:    K.L. Page at U Leicester <klp5@leicester.ac.uk>


K. L. Page (U Leicester), S. Dichiara (PSU), J.D. Gropp (PSU),
H. A. Krimm (NSF), T. M. Parsotan (GSFC/UMBC/CRESSTII) and
M. A. Williams (PSU) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 13:59:44 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230824A (trigger=1186959).  
The BAT on-board calculated location is 
RA, Dec 261.941, -16.215 which is 
   RA(J2000) = 17h 27m 46s
   Dec(J2000) = -16d 12' 53"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  As is common for image triggers, the BAT 
light curve does not show significant structure.  The duration 
appears to be about 20 sec.  The peak count rate was ~1400 
counts/sec (15-350 keV), at ~6 sec after the trigger. 

Due to a Moon observing constraint, Swift cannot slew to the BAT
position until 09:35 UT on 2023 August 27. There will thus be no XRT or
UVOT data for this trigger before this time. 

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: GRB230824B
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34538
SUBJECT: GRB 230824B: AstroSat CZTI detection
DATE:    23/08/24 17:21:58 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

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

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a GRB 230824B which was also detected by GECAM-B (Trigger Num. 214).

The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2023-08-24 02:26:50.45 UTC. We see at least two narrow distinct emission episodes. The measured peak count rate associated with the burst is 1044 (+201, -147) counts/s above the background in the combined data of all quadrants, with a total of 704 (+170, -185) counts. The local mean background count rate was 464 (+7, -9) counts/s. Using cumulative rates for the full burst, we measure a T90 of 4.0 (+1.5, -1.4) s. 

The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2023-08-24 02:26:50.21 UTC. The measured peak count rate associated with the burst is 292 (+71, -46) counts/s above the background in the combined data of all quadrants, with a total of 824 (+293, -358) counts. The local mean background count rate was 1529 (+5, -5) counts/s. We measure a T90 of 5.9 (+3.7, - 3.9) s from the cumulative Veto light curve.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at: 
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230824A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34540
SUBJECT: GRB 230824A is likely a Galactic Transient: Swift J1727.8-1613
DATE:    23/08/24 18:57:10 GMT
FROM:    Jamie Kennea at Penn State U <jak51@psu.edu>

Jamie A. Kennea (PSU) reports on behalf of the Swift Team

GRB 230824A (GCN #34537) reported by Swift/BAT, previously triggered INTEGRAL at 12:20UT (Weak trigger #10373,0) 100 mins before the BAT trigger,  and continued to trigger INTEGRAL several times after the BAT trigger. Given this, and its location in the Galactic Bulge (l,b = 8.64, 10.241), we now believe this is a likely Galactic Transient and not a GRB.

We therefore rename this source Swift J1727.8-1613. Observations to confirm the nature of this transient are requested. Swift will not observe this transient until at least  August 27, 2023 due to the proximity of the Moon.


GRB_name: GRB230824A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34542
SUBJECT: Trigger 1186982: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
DATE:    23/08/24 19:09:08 GMT
FROM:    K.L. Page at U Leicester <klp5@leicester.ac.uk>


S. Dichiara (PSU), J. A. Kennea (PSU), K. L. Page (U Leicester),
T. M. Parsotan (GSFC/UMBC/CRESSTII) and M. A. Williams (PSU) report on
behalf of the Neil Gehrels Swift Observatory Team:

At 18:54:32 UT, the Swift Burst Alert Telescope (BAT) triggered and
located Swift J1727.8-1613. Due to a Moon observing constraint, Swift 
cannot observe this location until 09:35 UT on 2023 August 27. 

We note this is the 2nd time BAT has triggered on this source,
previously named GRB 230824A (GCN #34537), now likely a Galactic
transient Swift J1727.8-1613 (GCN #34540)


GRB_name: GRB230824A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34543
SUBJECT: GRB 230824A: AKO Optical Afterglow Candidate
DATE:    23/08/24 19:12:43 GMT
FROM:    Mohammad Odeh at Al Khatim Observatory M44 <mshodeh@gmail.com>

Mohammad Odeh, Osama Ghannam, Anas Mohammad, Khalfan Al-Noaimy, and Sameh
Al-Ashi, report on behalf of Al-Khatim Observatory (AKO) operated by the
International Astronomical Center in Abu Dhabi, UAE:

We observed the field of GRB 230824A (Page et al., GCN 34537; Navaneeth et
al., GCN 34538) with our 0.36m f/7.7 robotic telescope. The observation
started at 18:04 UT on 24 August 2023, 4.1 hours after the trigger.

We obtained multiple 180-sec exposures in R filter. We detected a bright
star with a magnitude of R=13.5 at:
R.A. (J2000): 17:27:43.32
Dec. (J2000): -16:12:19.2

Which is within the uncertainty radius of the localization determined by
Swift team (Page et al., GCN 34537), however, our detected object is a
transient object (AT 2023qql) which was discovered today at 14:37:22 (UT)
0.6 hours after the GRB trigger, so more observations are required to
confirm this link.
https://www.wis-tns.org/object/2023qql


GRB_name: GRB230824A
Detection_method: MAXI Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34544
SUBJECT: MAXI/GSC detection of Swift J1727.8-1613 (GRB 230824A)
DATE:    23/08/25 02:25:47 GMT
FROM:    Motoko Serino at Aoyama Gakuin U. <serino@phys.aoyama.ac.jp>

H. Negoro (Nihon U.), M. Serino (AGU), M. Nakajima, K. Kobayashi, M. Tanaka, Y. Soejima, Y. Kudo (Nihon U.), 
T. Mihara, T. Kawamuro, S. Yamada, T. Tamagawa, N. Kawai, M. Matsuoka (RIKEN), 
T. Sakamoto, S. Sugita, H. Hiramatsu, H. Nishikawa, A. Yoshida (AGU), 
Y. Tsuboi, S. Urabe, S. Nawa, N. Nemoto (Chuo U.), M. Shidatsu (Ehime U.), 
I. Takahashi, M. Niwano, S. Sato, N. Higuchi, Y. Yatsu (Tokyo Tech), 
S. Nakahira, S. Ueno, H. Tomida, M. Ishikawa, S. Ogawa, T. Kurihara (JAXA), 
Y. Ueda, K. Setoguchi, T. Yoshitake, Y. Nakatani (Kyoto U.), 
M. Yamauchi, Y. Hagiwara, Y. Umeki, Y. Otsuki (Miyazaki U.), 
K. Yamaoka (Nagoya U.), Y. Kawakubo (LSU), M. Sugizaki (NAOC), and W. Iwakiri (Chiba U.) 
report on behalf of the MAXI team:

 The MAXI/GSC has detected the hard X-ray transient  Swift J1727.8-1613 (GRB 230824A: 
GCN #34536, #34537) since the scan transit at 10:20 on 2023 August 24.
The source flux is increasing rapidly, reaching more than 2 Crab at 10-20 keV at 21:10 and
22:44, which supports the possibility that the source is a Galactic transient, not a GRB 
(GCN #23540).
 The hard and rapid variations suggest that the source is a V404 Cyg like object.
Followup observations are highly encouraged. 
We cross-post this report to the ATel and the GCN.


GRB_name: GRB230824A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34547
SUBJECT: Trigger 1187142: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
DATE:    23/08/25 09:16:38 GMT
FROM:    P.A. Evans at U. Leicester <pae9@leicester.ac.uk>


S. Dichiara (PSU), P. A. Evans (U Leicester) and
K. L. Page (U Leicester) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 09:03:36 UT, the Swift Burst Alert Telescope (BAT) triggered and located
Swift J1727.8-1613 (trigger number 1187142); this is the third BAT trigger on
this event (GCN Circ. 34537; GCN Circ. 34542) which remains unobservable with
XRT and UVOT until 09:35 UT on 2023 August 27; however, MAXI have reported a
very bright (>2 Crab) 10-20 keV X-ray counterpart. This object is believed to be
a Galactic transient, Swift J1727.8-1613 (GCN Circ. 34540). 


GRB_name: GRB230824A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34549
SUBJECT: NICER detection of Swift J1727.8-1613 (GRB 230824A)
DATE:    23/08/25 17:08:08 GMT
FROM:    Brendan O'Connor at UMD <oconnorb@umd.edu>

Brendan O'Connor (Carnegie Mellon University), Jeremy Hare (NASA/GSFC/CRESST/CUA), George Younes (NASA/GSFC), Keith Gendreau (NASA/GSFC), Zaven Arzoumanian (NASA/GSFC), Elizabeth Ferrara (NASA/GSFC/CRESST/UMCP):

Following reports of repeated bursts from Swift J1727.8-1613 (GCN #34540) â€” initially designated GRB 230824A (GCN #34536, GCN #34537; see also ATels #16205, #16206) â€” we have observed the source with a NICER ToO, prior to the telescope entering a Moon constraint. The observation started on 2023-08-25 at 00:25:40 UT and ended at 00:49:53 UT, with a total exposure of 1,055 s. 

The observation began during orbit-day, which, due to the high count rate and a recent light â€œleakâ€ in NICERâ€™s X-ray Timing Instrument, led to telemetry saturation that created fragmented good-time intervals (GTIs). This is a known issue that leads to a 55 Hz â€œsignalâ€ (and potentially other significant features) in a power-spectral analysis. We caution future observers against astrophysical interpretations of this signal. To minimize calibration complications due to visible-light loading, we restricted our spectral analysis to only the nighttime data, with an exposure of 198 s.

Throughout the observation, the source is prominently detected with a count rate varying between ~5,000 and 20,000 cts/s. Rapid (timescales less than one second) variability is observed, similar to the black-hole system V404 Cyg (ATel #16205, ATel #16206) and/or the neutron-star binary Swift J1858.6â€“0814 (ATel #12158). In the orbit-night-only data, the 55 Hz signal is no longer visible in power spectra, which lack narrow features (no obvious QPO or sharply periodic signal) but are dominated by a strong red-noise component. 

We modeled the time-averaged spectrum (0.5-10 keV) with an absorbed power-law model plus a blackbody. We derive a photon index of 1.47+/-0.01, blackbody temperature of kT = 0.269+/-0.006 keV, and hydrogen column density of N_H = (2.26+/-0.05)e21 cm^-2. The PL+BB model fits the data well with a chi-squared of 87 for 155 degrees of freedom. We identify a hint of an iron line at around 6.4 keV. The absorption-corrected X-ray flux in the 0.5-10 keV energy band is (5.34+/-0.02)e-8 erg/cm^2/s. Assuming a distance of 3 - 6 kpc this corresponds to an X-ray luminosity of ~5e37 to 2e38 erg/s, which suggests that this is a newly discovered X-ray binary in outburst (ATel #16205, GCN #34540).

Further analysis is ongoing and additional NICER observations are planned. 

NICER is a 0.2-12 keV X-ray telescope operating on the International Space Station. The NICER mission and portions of the NICER science team activities are funded by NASA.


GRB_name: GRB230812B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34552
SUBJECT: GRB 230812B: radio detection with the VLA
DATE:    23/08/25 18:17:37 GMT
FROM:    Stefano Giarratana at University of Bologna <s.giarratana@ira.inaf.it>

S. Giarratana (University of Bologna, INAF-IRA), M. Giroletti
(INAF-IRA), G. Ghirlanda (INAF-OAB), N. Di Lalla (Stanford Univ.),
N. Omodei (Stanford Univ.)

At 01:52:24 UT on 2023 August 15 (T_mid = 2.3 days post-burst) the
Karl G. Jansky VLA observed the field of GRB 230812B (Fermi GBM
team, GCN 34386) at a central frequency of 6 and 10 GHz.

The standard J1331+3030 was used as bandpass and flux density
calibrator, while J1637+4717 was used as phase calibrator.

From a preliminary analysis, an unresolved radio source (Rhodes et al.,
GCN 34433; de Ugarte Postigo et al., GCN 34468) is clearly detected
at both frequencies at a position:

RA: 16:36:31.477 +- 0.001
Dec: +47:51:32.25 +- 0.02

The surface brightness peak is 230 uJy/beam and 196 uJy/beam at 6
and 10 GHz, respectively. The r.m.s. noise level of the images is
10 uJy/beam and 7 uJy/beam at 6 and 10 GHz, respectively.
The synthesized beams are 0.31 x 0.26 arcsec (PA: -45deg) at 6 GHz
and 0.20 x 0.16 arcsec (PA: -45deg) at 10 GHz.

We would like to thank the staff of the VLA for approving, executing,
and processing the observations.

The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc.

These observations were carried out as part of project SF161095,
approved in the framework of the Fermi - NRAO joint program agreement.


GRB_name: GRB230824A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34554
SUBJECT: Trigger 1187203:  Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
DATE:    23/08/25 20:33:01 GMT
FROM:    K.L. Page at U Leicester <klp5@leicester.ac.uk>


S. Dichiara (PSU), N. J. Klingler (GSFC/UMBC/CRESSTII),
M. J. Moss (GWU) and K. L. Page (U Leicester) report on behalf of the
Neil Gehrels Swift Observatory Team:

At 20:20:32 UT, the Swift Burst Alert Telescope (BAT) triggered again
on the Galactic transient Swift J1727.8-1613 (trigger number
1187203); this is the fourth BAT trigger on this event (GCN Circ. 
34537, 34542 and 34547). Swift XRT and UVOT observations are planned
for after the source exits Moon constraint on August 27. 


GRB_name: GRB230824A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34555
SUBJECT: Trigger 1187207: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
DATE:    23/08/25 21:05:28 GMT
FROM:    Simone Dichiara at Pennsylvania State University <sbd5667@psu.edu>


S. Dichiara (PSU) and T. M. Parsotan (GSFC/UMBC/CRESSTII) report on
behalf of the Neil Gehrels Swift Observatory Team:



At 20:27:20 UT, the Swift Burst Alert Telescope (BAT) triggered again
on the Galactic transient Swift J1727.8-1613 (AKA GRB 230824A) (trigger number
1187203); this is the fourth BAT trigger on this event (GCN Circ. 
34537, 34542 and 34547). Swift XRT and UVOT observations are planned
for after the source exits Moon constraint on August 27. 


GRB_name: GRB230824A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34556
SUBJECT: Swift J1727.8-1613 (GRB 230824A): Skynet Optical Observations
DATE:    23/08/25 21:25:27 GMT
FROM:    Dylan Dutton at UNC Chapel Hill <ddutton59@gmail.com>

Dylan Dutton, Daniel Reichart, Joshua Haislip, Vladimir Kouprianov, Daryl Janzen, Arie Verveer, John Kennewell, Megan Dubay, Ruide Fu, Logan Selph, and Donovan Schlekat report on behalf of the Skynet Robotic Telescope Network at the University of North Carolina at Chapel Hill.

We observed the field of Swift J1727.8-1613  (GRB 230824A) (Page et al., GCN 34537; Navaneeth et al., GCN 34538, Odeh et al., GCN 34543) with our 0.4m robotic telecope located in Meckering, Australia. The observation began at 14:11:20 UTC on Aug 24 2023, approximately 11 minutes after the first trigger.

We obtained multiple expsoures in the B, V, R, and I filters. Exposure lengths were calculated using our automated exposure length scaling model.

We detected a bright object, in the same location as Odeh et al., GCN 34543, within the uncertainty radius of the Swift localization, at:
R.A. (J2000): 17:27:43.34
Dec. (J2000): -16:12:19.161

Below, we report our photometric measurements.
-------------------------------------------
Date TimeTakenUTC ExpTime Filter Mag MagErr
-------------------------------------------
08-24-2023 | 14:11:20 | 25.721s | B | 14.22 | 0.013
08-24-2023 | 14:11:52 | 28.873s | V | 13.88 | 0.011
08-24-2023 | 14:12:29 | 13.756s | R | 13.69 | 0.012
08-24-2023 | 14:12:49 | 10.774s | I | 13.60 | 0.014
08-24-2023 | 14:15:50 | 37.756s | B | 14.25 | 0.010
08-24-2023 | 14:16:34 | 40.014s | V | 13.89 | 0.008
08-24-2023 | 14:17:21 | 19.012s | R | 13.69 | 0.009
08-24-2023 | 14:17:46 | 15.507s | I | 13.67 | 0.012
08-24-2023 | 14:21:35 | 56.372s | V | 13.89 | 0.007
08-24-2023 | 14:25:40 | 63.628s | B | 14.26 | 0.007
08-24-2023 | 14:26:49 | 66.016s | V | 13.88 | 0.006
08-24-2023 | 14:28:02 | 31.063s | R | 13.64 | 0.006
08-24-2023 | 14:28:40 | 24.327s | I | 13.60 | 0.008
08-24-2023 | 14:33:49 | 84.567s | B | 14.25 | 0.006
08-24-2023 | 14:35:19 | 88.210s | V | 13.86 | 0.005
08-24-2023 | 14:36:53 | 40.934s | R | 13.65 | 0.005
08-24-2023 | 14:37:40 | 32.058s | I | 13.63 | 0.007
08-24-2023 | 14:43:26 | 109.523s | B | 14.25 | 0.006
08-24-2023 | 14:45:23 | 113.289s | V | 13.89 | 0.005
08-24-2023 | 14:47:22 | 51.216s | R | 13.67 | 0.005
08-24-2023 | 14:48:20 | 41.685s | I | 13.61 | 0.007
08-24-2023 | 14:54:51 | 140.854s | B | 14.25 | 0.006
08-24-2023 | 14:57:17 | 147.908s | V | 13.88 | 0.005
08-24-2023 | 14:59:52 | 65.83s | R | 13.65 | 0.006
08-24-2023 | 15:01:05 | 53.273s | I | 13.58 | 0.007
08-24-2023 | 15:09:40 | 177.571s | B | 14.15 | 0.005
08-24-2023 | 15:15:54 | 83.812s | R | 13.65 | 0.006
08-24-2023 | 15:17:25 | 67.06s | I | 13.56 | 0.006
08-24-2023 | 15:27:51 | 225.946s | B | 14.23 | 0.006
08-24-2023 | 15:31:42 | 232.571s | V | 13.86 | 0.006
08-24-2023 | 15:35:41 | 105.216s | R | 13.61 | 0.006
08-24-2023 | 15:37:32 | 82.401s | I | 13.60 | 0.007
08-24-2023 | 15:50:16 | 284.651s | B | 14.31 | 0.006
08-24-2023 | 15:55:06 | 293.376s | V | 13.81 | 0.004
08-24-2023 | 16:00:07 | 131.78s | R | 13.57 | 0.005
08-24-2023 | 16:02:25 | 106.593s | I | 13.51 | 0.005
08-24-2023 | 16:30:17 | 164.791s | R | 13.53 | 0.006
08-24-2023 | 16:33:08 | 133.318s | I | 13.50 | 0.009

Our images have been calibrated using stars from the APASS catalog.


GRB_name: GRB230824A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34557
SUBJECT: Trigger 1187225: Swift detection of Swift J1727.8-1613 (AKA GRB 230824A)
DATE:    23/08/25 23:43:16 GMT
FROM:    Tyler Parsotan at UMBC/GSFC/CRESST II <parsotat@umbc.edu>


T. M. Parsotan (GSFC/UMBC/CRESSTII) and T. Sakamoto (AGU) report on
behalf of the Neil Gehrels Swift Observatory Team:

At 23:31:52 UT, the Swift Burst Alert Telescope (BAT) triggered again
on the Galactic transient Swift J1727.8-1613 (AKA GRB 230824A) (trigger number
1187203); this is another BAT trigger on this event (see eg GCN Circ. 
34537, 34542 and 34547). Swift XRT and UVOT observations are planned
for after the source exits Moon constraint on August 27. 


GRB_name: GRB230818B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34560
SUBJECT: GRB 230818B: CALET Gamma-Ray Burst Monitor detection
DATE:    23/08/26 04:35:14 GMT
FROM:    Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>

Y. Shimizu (Kanagawa U), A. Yoshida, T. Sakamoto, 
S. Sugita (AGU), Y. Kawakubo (LSU),K. Yamaoka (Nagoya U),
S. Nakahira (JAXA), Y. Asaoka (ICRR), S. Torii, Y. Akaike, 
K. Kobayashi (Waseda U), T. Tamura (Kanagawa U), 
N. Cannady (GSFC/UMBC),
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The long GRB 230818B (AstroSat CZTI detection: 
Navaneeth et al., GCN Circ. 34524; VZLUSAT-2 detection: 
Dafcikova et al., GCN Circ. 34525; Konus/Wind detection at 
2023-08-18 10:12:54.913 UT) triggered the CALET Gamma-ray 
Burst Monitor (CGBM) at 10:12:54.02 UTC on 18 August 2023
(http://cgbm.calet.jp/cgbm_trigger/flight/1376388662/).
The burst signal was seen by all CGBM detectors.
Because of a problem in one of the ground alert processing script,
the GCN notice was not distributed automatically for this event.

The burst light curve shows a multi-peaked structure that starts
at T-0.6 sec, peaks at T+0.6 sec, and ends at T+32.0 sec.
The T90 and T50 durations measured by the SGM data are 27.6 +/- 1.2 sec
and 13.3 +/- 0.6 sec (40-1000 keV), respectively.

The ground-processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1376388662/index.html

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


GRB_name: GRB230824A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34561
SUBJECT: GRB 230824A: AKO Photometric Follow-up Observations
DATE:    23/08/26 07:30:58 GMT
FROM:    Mohammad Odeh at Al Khatim Observatory M44 <mshodeh@gmail.com>

Mohammad Odeh, Osama Ghannam, Anas Mohammad, Khalfan Al-Noaimy, and Sameh
Al-Ashi, report on behalf of Al-Khatim Observatory (AKO) operated by the
International Astronomical Center in Abu Dhabi, UAE:

As a follow-up for the GRB 230824A (Page et al., GCN 34537), also known as
Swift J1727.8-1613 (Dichiara et al., GCN 34542), also known as AT 2023qql
 (Zhang and Gao, https://www.wis-tns.org/object/2023qql), we observed the
target with our 0.36m f/7.7 robotic telescope for the second night on 25
August 2023, and we obtained multiple 180-sec exposures in R filter. The
below table summarizes the results of the two nights:

R.A. (J2000)= 17:27:43.32
Dec. (J2000)= -16:12:19.2
-----------------------------------------------------------------------------
ObsTime (mid), t(mid) â€“ t(0) (hours), Exposure (sec), Filter, Mag
-----------------------------------------------------------------------------
2023-08-24T18:29:24Z, 04.5, 180s, R, 13.5 +/- 0.04
2023-08-25T16:29:44Z, 26.5, 180s, R, 13.0 +/- 0.01
-----------------------------------------------------------------------------

The observations were calculated using the Atlas catalogue as a reference
and are not corrected for galactic extinction.

The object is added to The International Variable Star Index catalogue and
photometric observations can be submitted through AAVSO website.

Object Page:
https://www.aavso.org/vsx/index.php?view=detail.top&oid=2387757

Submission Form:
https://www.aavso.org/webobs

Current Photometric Results:
https://www.aavso.org/LCGv2/


GRB_name: GRB230824A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34562
SUBJECT: Swift J1727.8-1613 (GRB 230824A): Bassano Bresciano Observatory optical observations
DATE:    23/08/26 08:05:10 GMT
FROM:    Ulisse Quadri at Bassano Bresciano Obs <oabb@ulisse.bs.it>

U.Quadri, P.Madurini and L.Strabla (Bassano Bresciano Astronomical Observatory),

Member of: 
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.
GAC - Gruppo Astrofili Cremonesi.

in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan), 
Y. Niino (Tokyo University, Institute of Astronomy), 
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
report: 

We imaged the field of Swift J1727.8-1613(GRB 230824A) 
(Page et al., GCN 34537; Navaneeth et al., GCN 34538, Odeh et al., GCN 34543)
with the following telescopes:

0.25-m f/4.8 Newton reflector at Bassano Bresciano Observatory, Italy - MPC Code 565. 
0.32-m f/8.0 (iTelescope) reflector at AstroCamp at Nerpio, Spain - MPC Code I89.
0.51-m f/6.8 (iTelescope) Dall-Kirkham at Rio Hurtado Valley, Chile - MPC Code X07. 
 

We clearly detected a bright object, in the same location as M.Odeh et al., GCN 34543, within 
the uncertainty radius of the Swift localization, at:

R.A. (J2000): 17:27:43.32
Dec. (J2000): -16:12:18.8


The results of our photometry are:

------------------------------------------------------    
    Date UT       Exp Time   R-mag    Err  IAU STATION
------------------------------------------------------
  
2023-08-24.7967    18x20s    13.25   0.057    565
2023-08-24.8018    18x20s    13.25   0.049    565  
2023-08-24.8071    12x30s    13.24   0.048    565 
2023-08-24.8124    12x30s    13.24   0.043    565 
2023-08-24.8185    12x30s    13.24   0.042    565 
2023-08-24.9030    10x60s    13.05     -      I89
2023-08-25.1470    10x60s    12.80     -      X07
------------------------------------------------------

Magnitudes were estimated with the pan-STARRS cat. 
and are converted using Lupton (2005) equations.

Not corrected for galactic dust extinction.

Further observations are planned.

Reference:
http://www.osservatoriobassano.org/GRB.asp

The message may be cited.


GRB_name: GRB230826A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34564
SUBJECT: GRB 230826A: Fermi GBM Final Real-time Localization
DATE:    23/08/26 19:43:17 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 19:32:44 UT on 26 Aug 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230826A (trigger 714771169.528076 / 230826814).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 82.8, Dec = 67.1 (J2000 degrees, equivalent to J2000 05h 31m, 67d 05'), with a statistical uncertainty of 2.0 degrees.

The angle from the Fermi LAT boresight is 117.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230826814/quicklook/glg_skymap_all_bn230826814.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230826814/quicklook/glg_healpix_all_bn230826814.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230826814/quicklook/glg_lc_medres34_bn230826814.gif


GRB_name: GRB230826A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34565
SUBJECT: GRB 230826A: Swift detection of a burst
DATE:    23/08/26 20:16:03 GMT
FROM:    David Palmer at LANL <palmer@lanl.gov>


R. A. J. Eyles-Ferris (U Leicester), S. Dichiara (PSU),
J.D. Gropp (PSU), J. A. Kennea (PSU), D. M. Palmer (LANL),
T. M. Parsotan (GSFC/UMBC/CRESSTII), M. H. Siegel (PSU) and
A. Tohuvavohu (U Toronto) report on behalf of the Neil Gehrels Swift
Observatory Team:

At 19:32:47 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230826A (trigger=1187463).  Swift slewed immediately to
the location.  The BAT on-board calculated location is 
RA, Dec 83.012, +66.125 which is 
  RA(J2000) = 05h 32m 03s
  Dec(J2000) = +66d 07' 30"
with an uncertainty of 3 arcmin (radius, 90% containment, including 
systematic uncertainty).  Preliminary quicklook data suggests that the
light curve is doubly peaked with a T90 of ~50 sec and background 
subtracted peak count rate of ~4000 counts/sec at T0+3 sec. 

The XRT began observing the field at 19:34:03.7 UT, 76.7 seconds after
the BAT trigger. Using promptly downlinked data we find a bright,
uncatalogued X-ray source located at RA, Dec 83.05920, 66.12506 which
is equivalent to:
   RA(J2000)  =  5h 32d 14.2s,
   Dec(J2000) = 66h 07d 30.2s
with an uncertainty of 10.0 arcseconds (radius, 90% containment). This
location is 69 arcseconds from the BAT onboard position, within the BAT
error circle. 

Due to a telemetry gap, no further information is available at
this time.  However a simultaneous Fermi trigger (GCN #34564) 
confirms the GRB. 

Burst Advocate for this burst is R. A. J. Eyles-Ferris (raje1 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: GRB230824A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34566
SUBJECT: Swift J1727.8-1613 (GRB 230824A): GAD Observatory La Spezia - optical observations
DATE:    23/08/26 20:45:21 GMT
FROM:    Claudio Lopresti <cl3lop@gmail.com>

Claudio Lopresti (Gruppo Astronomia Digitale - GAD Observatory, La Spezia, Italy - UAI SSV- GRB Section)
in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan),
Y. Niino (Tokyo University, Institute of Astronomy),
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
Unione Astrofili Italiani (UAI SSV- GRB Section)
report:

I imaged the field of of Swift J1727.8-1613 (GRB 230824A) (Page et al., GCN 34537; Navaneeth et al., GCN 34538, Odeh et al., GCN 34543) with the following telescope: 0.18-m f/4 Mak-Newton reflector at GAD Observatory, Italy, with filters Infrared, Red, and V.  I clearly detected a bright object, in the same location as M.Odeh et al., GCN 34543, within the uncertainty radius of the Swift localization, at: R.A. (J2000): 17:27:43.32 Dec. (J2000): -16:12:18.8.

The results of photometry are:

In Infrared band:
=============================================
         Date UT         Exp Time   I-mag    Err
=============================================
2460181.3096064800    90s    13.71    0.10
2460181.3143750000    90s    13.85    0.08
2460181.3191319400    90s    13.83    0.04
2460181.3239004600    90s    13.78    0.03
2460181.3286689800    90s    13.80    0.02
2460181.3334259200    90s    13.82    0.06
2460181.3519444400    90s    13.90    0.09
2460181.3559490700    180s    13.72    0.09
2460181.3599537000    180s    13.79    0.05
2460181.3639583300    180s    13.69    0.03
2460181.3679745300    180s    13.73    0.03
2460181.3719907400    180s    13.83    0.07
2460181.3760069400    180s    13.71    0.09


In Red band:
=============================================
        Date UT         Exp Time  R-mag   Err
=============================================
2460181.3119675900    90s    14.09    0.00
2460181.3167361100    90s    14.09    0.02
2460181.3215046200    90s    14.05    0.04
2460181.3262615700    90s    14.14    0.05
2460181.3310300900    90s    14.15    0.08
2460181.3532407400    90s    14.01    0.07
2460181.3572569400    180s    14.06    0.05
2460181.3612615700    180s    13.96    0.06
2460181.3652662000    180s    13.96    0.00
2460181.3692824000    180s    13.96    0.01
2460181.3732986100    180s    13.98    0.01


In V band:
=============================================
           Date UT        Exp Time  V-mag    Err
=============================================
2460181.3586111100    90s    13.51    0.09
2460181.3626157400    90s    13.37    0.07
2460181.3666203700    90s    13.44    0.04
2460181.3706365700    90s    13.46    0.01
2460181.3746527700    90s    13.45    0.01


Magnitudes were estimated with the PanSTARRS cat., not corrected for galactic dust extinction. Weather conditions were good.

Reference:
https://www.parcodellestelle.com/

The message may be cited. 


GRB_name: GRB230826A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34567
SUBJECT: GRB 230826A: Mondy optical observations
DATE:    23/08/27 01:28:38 GMT
FROM:    Alexei Pozanenko at IKI, Moscow <apozanen@iki.rssi.ru>

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

We observed the field of GRB 230826A detected by Fermi GBM (Fermi GBM Team, GCN 34564) and Swift (Eyles-Ferris et al, 34565) with AZT-33IK telescope of Sayan observatory (Mondy).  Observations started on 2023-08-26 220:06:00  (UT) (i.e. ~33 min since trigger). We obtained  
series of images in R-filter. We do not detect evident candidate within XRT error  circle (Swift-XRT Position: +05h 32m 14.20s +66d 07' 30.0" 5.3 arcsec, radius) in a stacked image.  Preliminary photometry is following:

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

2023-08-26 20:06:00   0.038345  R     44*60  n/d  n/d   22.0

We note the presence of the object USNO-B1.0 1561-0095652 at 8.8 arces from the Swift-XRT Position. Measured brightness of the object is R = 18.1 +/- 0.01 what is brighter than USNO-B1.0 R2=18.22 magnitude.

All photometry is based on nearby USNO-B1.0 stars, R2 magnitudes


GRB_name: GRB230826A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34568
SUBJECT: GRB 230826A: Swift-XRT refined Analysis
DATE:    23/08/27 07:26:29 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

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

We have analysed 8.3 ks of XRT data for GRB 230826A, from 65 s to 29.5
ks after the  BAT trigger. The data comprise 56 s in Windowed Timing
(WT) mode (the first 8 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode. The refined XRT position is RA,
Dec = 83.0642, +66.1244 which is equivalent to:

RA (J2000): 05 32 15.41
Dec(J2000): +66 07 27.9

with an uncertainty of 3.5 arcsec (radius, 90% confidence).

The light curve can be modelled with a series of power-law decays. The
initial decay index is alpha=3.44 (+0.25, -0.24). At T+213 s  the decay
flattens to an alpha of -0.06 (+0.24, -0.26) before breaking again at
T+1264 s to a final decay with index alpha=1.39 (+0.22, -0.14).

A spectrum formed from the WT mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.93 (+0.32, -0.29). The
best-fitting absorption column is  4.7 (+1.0, -0.9) x 10^21 cm^-2, in
excess of the Galactic value of 1.5 x 10^21 cm^-2 (Willingale et al.
2013). The PC mode spectrum has a photon index of 2.15 (+0.22, -0.21)
and a best-fitting absorption column of 4.4 (+1.1, -1.0) x 10^21 cm^-2.
The counts to observed (unabsorbed) 0.3-10 keV flux conversion factor
deduced from this spectrum  is 3.6 x 10^-11 (6.3 x 10^-11) erg cm^-2
count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      4.4 (+1.1, -1.0) x 10^21 cm^-2
Galactic foreground: 1.5 x 10^21 cm^-2
Excess significance: 4.8 sigma
Photon index:      2.15 (+0.22, -0.21)

If the light curve continues to decay with a power-law decay index of
1.39, the count rate at T+24 hours will be 2.8 x 10^-3 count s^-1,
corresponding to an observed (unabsorbed) 0.3-10 keV flux of 1.0 x
10^-13 (1.8 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/01187463.

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


GRB_name: GRB230826A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34569
SUBJECT: GRB 230826A: Enhanced Swift-XRT position
DATE:    23/08/27 07:40:11 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.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 1910 s of XRT Photon Counting mode data and 5 UVOT
images for GRB 230826A, 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 = 83.06410, +66.12384 which is equivalent
to:

RA (J2000): 05h 32m 15.38s
Dec (J2000): +66d 07' 25.8"

with an uncertainty of 2.0 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: GRB230824A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34570
SUBJECT: Swift J1727.8-1613 (GRB 230824A): Leavitt Observatory optical observations
DATE:    23/08/27 10:40:23 GMT
FROM:    leavittob@gmail.com

E. Pavoni and L. Moretti (Leavitt Observatory, Italy), in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan), 
Y. Niino (Tokyo University, Institute of Astronomy), 
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (UniversitÃ  degli Studi Di Salerno)
report: 

We observed the field of Swift J1727.8-1613 (GRB 230824A: Page et al., GCN 34537; Navaneeth et al., GCN 34538, Odeh et al., GCN 34543; U.Quadri et al., GCN 34562; C. Lopresti, GCN 34566) with the telescope of Leavitt Observatory, Italy. Member of: 

UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili, GRB section.
ATA - Associazione Tuscolana di Astronomia.

The observations began at 20:02 UT on 2023/08/24 (~6 hours after the Swift trigger), with our RC telescope D=250 mm F/D=8.

Weather conditions were good.

We took 25 images of 120 sec each. All images are Rc filtered, calibrated with master dark and master flat, stacked with ASTAP software and analyzed with AstroImageJ software.

We clearly detected a bright object, in the same location as M.Odeh et al., GCN 34543, within the uncertainty radius of the Swift localization, at:

R.A. (J2000): 17:27:43.32
Dec. (J2000): -16:12:18.8

The results of our photometry in Rc band are:

JD_UTC           Source_Mag Source_Mag_Err
2460181.3385997  13,766           0,006   
2460181.3457458  13,725           0,006   
2460181.3528939  13,731           0,006
2460181.3603810  13,694           0,006
2460181.3689481  13,671           0,005

Magnitudes were estimated with PanSTARRS cat. and are not corrected for galactic dust extinction.

The message may be cited.


GRB_name: GRB230826A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34571
SUBJECT: GRB 230826A: Fermi GBM Observation
DATE:    23/08/27 11:36:56 GMT
FROM:    rachel.hamburg@ijclab.in2p3.fr

O.J. Roberts (USRA) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 19:32:44.53 UT on 26 August 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230826A (trigger 714771169/230826814),
which was also detected by Swift-BAT (R.A.J. Eyles-Ferris  et al. 2023, GCN 34565).
The Fermi GBM Final Real-time Localization (GCN 34564) is consistent with the Swift-BAT position.

The angle from the Fermi LAT boresight is 116 degrees.

The GBM light curve consists of a single FRED peak with a duration (T90)
of about 37 s (50-300 keV). The time-averaged spectrum
from T0-4.1 to T0+46.1 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.75 +/- 0.12 and the cutoff energy,
parameterized as Epeak, is 87 +/- 5 keV.

The event fluence (10-1000 keV) in this time interval is
(6.012 +/- 0.246)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+4.9 s in the 10-1000 keV band is 4.9 +/- 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: GRB230826A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34572
SUBJECT: GRB 230826A: GRBAlpha detection
DATE:    23/08/27 14:13:41 GMT
FROM:    Marianna DafÄÃ­kovÃ¡ at Masaryk University <500025@mail.muni.cz>

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

The long-duration GRB 230826A (Fermi/GBM detection: GCN 34564; Swift/BAT detection: GCN 34565) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023; arXiv:2302.10048).

The detection was confirmed at the peak time 2023-08-26 19:32:45 UTC. The T90 duration measured by GRBAlpha is 18 s and the overall significance during T90 reaches 8.3 sigma.

The light curve obtained by GRBAlpha is available here: https://grbalpha.konkoly.hu/static/share/GRB230826A_GCN.pdf

All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/ 
GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume. 


GRB_name: GRB230824A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34573
SUBJECT: Swift J1727.8-1613 (GRB 230824A): Montarrenti Observatory photometric observations
DATE:    23/08/27 14:57:12 GMT
FROM:    Simone Leonini at Montarrenti Observatory (Siena, Italy) <s.leonini@iol.it>

S. Leonini, M. Conti, P. Rosi, L.M. Tinjaca Ramirez (Montarrenti Observatory, Siena, Italy) report:

We observed the field of Swift J1727.8-1613 (GRB 230824A) 
(Page et al., GCN 34537; Odeh et al., GCN 34543; Dutton et al., GCN 34556; Odeh et al., GCN 34561; Quadri et al., GCN 34562; Lopresti, GCN 34566; Pavoni & Moretti, GCN 34570) with the remote controlled 0.53m Ritchey-Chretien telescope + U47 detector at Montarrenti Observatory (Siena, Italy, IAU code C88) in 2 epochs, starting on Aug 24.78994 (5 hours after trigger) and Aug. 26.79422 2023 (53 hours after trigger) with multiple exposures in V, Rc and Ic band.
 
The OT was detected at the following position:

RA     (J2000)  17h 27m 43.32s +/-0.2 
Dec. (J2000) -16Â°  12'   18.60" +/-0.2

Photometry was obtained using nearby PanSTARRS stars as follows:

==============================
Obs. midtime UT   Filter  Mag.  Err.
==============================

2460181.2962325     V     13.45  0.002
2460181.3049015     V     13.48  0.002
2460181.3127082     V     13.50  0.002
2460181.3205208     V     13.50  0.002
2460181.3305952     V     13.47  0.002

2460183.3018576     V     12.54  0.003
2460183.3062470     V     12.52  0.003
2460183.3143382     V     12.48  0.004  
2460183.3208796     V     12.50  0.004
-----------------------------------------------

2460181.2973320    R      13.39  0.001 
2460181.3053240    R      13.42  0.001
2460181.3131307    R      13.42  0.001
2460181.3213754    R      13.44  0.001
2460181.3315657    R      13.39  0.001

2460183.2976407    R      12.43  0.002
2460183.3047650    R      12.43  0.002
2460183.3089728    R      12.41  0.002 
2460183.3200694    R      12.44  0.002
-----------------------------------------------

2460181.2940451    I       13.29  0.002
2460181.3031443    I       13.28  0.002
2460181.3109548    I       13.26  0.002
2460181.3187615    I       13.22  0.002
2460181.3265489    I       13.26  0.001
2460181.3336487    I       13.26  0.001

2460183.2980439    I       12.28  0.003
2460183.3052912    I       12.26  0.003
2460183.3164382    I       12.27  0.003
2460183.3204745    I       12.26  0.003
-----------------------------------------------


Magnitudes were converted using Lupton 2005 equations and are not corrected for galactic dust extinction.

Further observations are planned. 


GRB_name: GRB230827A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34575
SUBJECT: GRB 230827A: Fermi GBM Final Real-time Localization
DATE:    23/08/27 18:28:19 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 18:17:52 UT on 27 Aug 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230827A (trigger 714853077.93055 / 230827762).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 319.1, Dec = -23.9 (J2000 degrees, equivalent to J2000 21h 16m, -23d 53'), with a statistical uncertainty of 1.0 degrees.

The angle from the Fermi LAT boresight is 95.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230827762/quicklook/glg_skymap_all_bn230827762.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230827762/quicklook/glg_healpix_all_bn230827762.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230827762/quicklook/glg_lc_medres34_bn230827762.gif


GRB_name: GRB230824A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34577
SUBJECT:  Swift J1727.8-1613 (GRB 230824A): Osservatorio Astronomico "Nastro Verde" optical observations
DATE:    23/08/27 19:24:18 GMT
FROM:    Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy - MPC Code C82 <osservatorionastroverde@gmail.com>

Nello Ruocco at Osservatorio Nastro Verde - Sorrento (Naples) - Italy
in a large collaboration with:
M.G. Dainotti (National Astronomical Observatory of Japan), 
Y. Niino (Tokyo University, Institute of Astronomy), 
K. Kalinowski (Aarhus University, Department of Physics and Astronomy),
B. De Simone (Universita' degli Studi Di Salerno)
report: 
Following the Swift trigger no. 1186959 (GCN 34537), we pointed at the coordinates RA(J2000)=17h 27m 46s: Dec(J2000)=-16d 12' 53" and started our observations with telescope of Nastro Verde Observatory - Sorrento (Naples), Italy.
Member of: 
AAVSO - American Association of Variable Star Observers.
UAI/SSV - Unione Astrofili Italiani/sezione stelle variabili.
AstroCampania Associazione.

The observations started at 19:23 UT of 2023/08/24, after about 5,25 hours after the GRB trigger, at the end of twilight with clear skies, with principal telescope  SC 0.35 f/10 with focal reduced + CCD Sbig ST10 XME
I took 9 image of 120 sec each in fotometric V and 13 in Rc . All images, calibrated with masterdark and masterflat have been measured with Maxim DL software
We have detected a clear visible source at the enhanced position reported by Swift Burst Alert Telescope (BAT) (Page et al., GCN 34537 ) and by other telescopes ( Jamie A. Kennea (PSU) et al GCN 34540., S. Dichiara (PSU) et al GCN 34542, 34547, 34554,34555., Mohammad Odeh et al GCN 34543, 34561., H. Negoro (Nihon U). et al GCN 34544., Brendan O'Connor et al GCN 34549.,Dylan Dutton et al GCN 34556., T. M. Parsotan et al GCN 34557., U.Quadri et al GCN 34562., Claudio Lopresti et al GCN 34566., S. Leonini et al GCN 34573) 
at following position

RA (J2000)   17:27:43.32
Dec (J2000) -16:12:19

with the following photometry:

    JD            Mag         Filter
2460181.317 13.69            V
2460181.32 13.74            V
2460181.323 13.66            V
2460181.326 13.59            V
2460181.329 13.63            V
2460181.332 13.55            V
2460181.335 13.54            V
2460181.338 13.62            V
2460181.341 13.55            V
 


JD           Mag        Filter
2460181.309 13.49            Rc
2460181.31 13.51            Rc
2460181.312 13.54            Rc
2460181.313 13.45            Rc
2460181.315 13.47            Rc
2460181.318 13.48            Rc
2460181.321 13.50            Rc
2460181.324 13.52            Rc
2460181.33 13.45            Rc
2460181.333 13.46            Rc
2460181.336 13.50            Rc
2460181.339 13.50            Rc
2460181.342 13.50            Rc



The magnitudes are calibrated with stars of the PanSTARRS catalog, espressed in AB system and are not corrected for the expected Galactic extinction.

The peculiar transient ( detected by other observatories ) is confirmed in our observations. Further observations are encouraged.


GRB_name: GRB230827A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34578
SUBJECT: Fermi GRB 230827A: Global MASTER-Net observations report
DATE:    23/08/27 19:31:03 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E.Gorbovskoy, K.Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, D. Vlasenko, 
G.Antipov, D.Zimnukhov, V.Senik, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov,  D.Cheryasov, Ya.Kechin
(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),

L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez, A.R.Corella, L.H.Rodriguez 
(INAOE, Guillermo Haro Astrophysics Observatory),

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

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


MASTER-Tavrida robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Lomonosov MSU, SAI Crimea astronomical station) started inspect of the Fermi GRB 230827A ( Fermi GBM team, GCN 34575) errorbox  53 sec after notice time and 86 sec after trigger time at 2023-08-27 18:19:18 UT, with upper limit up to  17.8 mag. The observations began at zenith distance = 74 deg. The sun  altitude  is -18.8 deg. 

MASTER-Kislovodsk robotic telescope  located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 230827A errorbox  61 sec after notice time and 94 sec after trigger time at 2023-08-27 18:19:27 UT, with upper limit up to  17.5 mag. The observations began at zenith distance = 70 deg. The sun  altitude  is -23.9 deg. 

The galactic latitude b = -42 deg., longitude l = 25 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2261859

We obtain a following upper limits.  

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

      96 | 2023-08-27 18:19:18 |      MASTER-Tavrida | (21h 16m 19.41s , -22d 49m 36.6s) |   C |    20 | 13.7 |        
     104 | 2023-08-27 18:19:27 |   MASTER-Kislovodsk | (21h 18m 43.33s , -22d 37m 28.1s) |   C |    20 | 15.5 |        
     104 | 2023-08-27 18:19:27 |   MASTER-Kislovodsk | (21h 23m 17.26s , -23d 01m 43.3s) |   C |    20 | 14.5 |        
     127 | 2023-08-27 18:19:49 |      MASTER-Tavrida | (21h 05m 33.35s , -22d 39m 05.5s) |   C |    20 | 15.1 |        
     145 | 2023-08-27 18:20:07 |   MASTER-Kislovodsk | (21h 18m 38.34s , -22d 38m 28.4s) |   C |    20 | 15.5 |        
     145 | 2023-08-27 18:20:07 |   MASTER-Kislovodsk | (21h 23m 12.27s , -23d 02m 45.3s) |   C |    20 | 14.6 |        
     159 | 2023-08-27 18:20:16 |      MASTER-Tavrida | (21h 05m 33.35s , -22d 38m 05.6s) |   C |    30 | 15.4 |        
     190 | 2023-08-27 18:20:47 |   MASTER-Kislovodsk | (21h 18m 44.53s , -22d 38m 17.4s) |   C |    30 | 15.8 |        
     190 | 2023-08-27 18:20:47 |   MASTER-Kislovodsk | (21h 23m 18.58s , -23d 02m 32.4s) |   C |    30 | 14.9 |        
     201 | 2023-08-27 18:20:53 |      MASTER-Tavrida | (21h 05m 39.14s , -22d 39m 06.7s) |   C |    40 | 15.7 |        
     245 | 2023-08-27 18:21:37 |   MASTER-Kislovodsk | (21h 18m 41.77s , -22d 36m 53.9s) |   C |    40 | 15.9 |        
     245 | 2023-08-27 18:21:37 |   MASTER-Kislovodsk | (21h 23m 16.72s , -23d 01m 12.9s) |   C |    40 | 14.6 |        
     311 | 2023-08-27 18:22:38 |   MASTER-Kislovodsk | (21h 18m 41.83s , -22d 38m 12.2s) |   C |    50 | 16.0 |        
     311 | 2023-08-27 18:22:38 |   MASTER-Kislovodsk | (21h 23m 16.69s , -23d 02m 30.9s) |   C |    50 | 14.6 |        
     391 | 2023-08-27 18:23:48 |   MASTER-Kislovodsk | (21h 18m 43.78s , -22d 36m 30.1s) |   C |    70 | 16.1 |        
     391 | 2023-08-27 18:23:48 |   MASTER-Kislovodsk | (21h 23m 18.49s , -23d 00m 48.5s) |   C |    70 | 14.8 |        
     663 | 2023-08-27 18:27:55 |   MASTER-Kislovodsk | (21h 15m 12.98s , -23d 39m 12.8s) |  P- |   120 | 16.5 |        
     828 | 2023-08-27 18:27:55 |   MASTER-Kislovodsk | (21h 15m 12.98s , -23d 39m 12.8s) |  P- |   450 | 17.4 |  Coadd 
     663 | 2023-08-27 18:27:55 |   MASTER-Kislovodsk | (21h 15m 11.97s , -24d 02m 49.0s) |  P| |   120 | 14.2 |        
     762 | 2023-08-27 18:29:24 |      MASTER-Tavrida | (21h 12m 25.92s , -23d 55m 20.9s) |   C |   140 | 16.4 |        
     818 | 2023-08-27 18:30:16 |   MASTER-Kislovodsk | (21h 15m 19.41s , -23d 40m 15.8s) |  P- |   150 | 16.6 |        
     818 | 2023-08-27 18:30:16 |   MASTER-Kislovodsk | (21h 15m 18.09s , -24d 03m 58.0s) |  P| |   150 | 15.0 |        
     926 | 2023-08-27 18:31:53 |      MASTER-Tavrida | (21h 12m 23.87s , -23d 54m 04.8s) |   C |   170 | 16.6 |        
    1109 | 2023-08-27 18:34:51 |      MASTER-Tavrida | (21h 12m 23.91s , -23d 55m 43.2s) |   C |   180 | 16.6 |        
    1204 | 2023-08-27 18:36:26 |   MASTER-Kislovodsk | (21h 15m 19.86s , -23d 40m 56.0s) |  P- |   180 | 16.8 |        
    1204 | 2023-08-27 18:36:26 |   MASTER-Kislovodsk | (21h 15m 19.22s , -24d 04m 35.5s) |  P| |   180 | 14.6 |        
    1297 | 2023-08-27 18:38:00 |      MASTER-Tavrida | (21h 12m 26.53s , -23d 53m 56.3s) |   C |   180 | 16.9 |        
    1404 | 2023-08-27 18:39:47 |   MASTER-Kislovodsk | (21h 15m 16.77s , -23d 39m 34.8s) |  P- |   180 | 16.7 |        
    1584 | 2023-08-27 18:39:47 |   MASTER-Kislovodsk | (21h 15m 16.78s , -23d 39m 34.7s) |  P- |   540 | 17.5 |  Coadd 
    1404 | 2023-08-27 18:39:47 |   MASTER-Kislovodsk | (21h 15m 15.26s , -24d 03m 02.1s) |  P| |   180 | 14.5 |        
    1484 | 2023-08-27 18:41:06 |      MASTER-Tavrida | (21h 12m 21.56s , -23d 54m 47.9s) |   C |   180 | 16.9 |        
    1605 | 2023-08-27 18:43:07 |   MASTER-Kislovodsk | (21h 15m 16.92s , -23d 40m 43.4s) |  P- |   180 | 16.8 |        
    1605 | 2023-08-27 18:43:07 |   MASTER-Kislovodsk | (21h 15m 16.75s , -24d 04m 26.4s) |  P| |   180 | 14.6 |        
    1670 | 2023-08-27 18:44:12 |      MASTER-Tavrida | (21h 12m 21.63s , -23d 53m 47.4s) |   C |   180 | 16.9 |        
    1806 | 2023-08-27 18:46:28 |   MASTER-Kislovodsk | (21h 15m 19.31s , -23d 39m 33.5s) |  P- |   180 | 16.8 |        
    1806 | 2023-08-27 18:46:28 |   MASTER-Kislovodsk | (21h 15m 18.56s , -24d 03m 08.4s) |  P| |   180 | 14.6 |        
    1858 | 2023-08-27 18:47:20 |      MASTER-Tavrida | (21h 12m 26.71s , -23d 54m 47.6s) |   C |   180 | 16.9 |        
    2006 | 2023-08-27 18:49:49 |   MASTER-Kislovodsk | (21h 15m 14.52s , -23d 40m 06.2s) |  P- |   180 | 16.7 |        
    2006 | 2023-08-27 18:49:49 |   MASTER-Kislovodsk | (21h 15m 13.77s , -24d 03m 41.7s) |  P| |   180 | 14.6 |        
    2046 | 2023-08-27 18:50:28 |      MASTER-Tavrida | (21h 12m 20.27s , -23d 55m 45.7s) |   C |   180 | 17.2 |        
    2234 | 2023-08-27 18:53:37 |      MASTER-Tavrida | (21h 12m 26.77s , -23d 55m 31.3s) |   C |   180 | 17.3 |        
    2424 | 2023-08-27 18:56:46 |      MASTER-Tavrida | (21h 12m 24.32s , -23d 53m 45.3s) |   C |   180 | 17.4 |        
    2612 | 2023-08-27 18:59:54 |      MASTER-Tavrida | (21h 12m 24.35s , -23d 55m 37.5s) |   C |   180 | 17.3 |        
    2750 | 2023-08-27 19:02:12 |   MASTER-Kislovodsk | (21h 15m 21.73s , -24d 03m 38.2s) |   C |   180 | 15.0 |        
    2750 | 2023-08-27 19:02:12 |   MASTER-Kislovodsk | (21h 15m 22.82s , -23d 39m 57.4s) |   C |   180 | 13.7 |        
    2801 | 2023-08-27 19:03:04 |      MASTER-Tavrida | (21h 12m 27.29s , -23d 53m 46.8s) |   C |   180 | 17.5 |        
    2950 | 2023-08-27 19:05:33 |   MASTER-Kislovodsk | (21h 15m 16.60s , -23d 40m 57.0s) |   C |   180 | 15.6 |        
    2950 | 2023-08-27 19:05:33 |   MASTER-Kislovodsk | (21h 15m 16.79s , -24d 04m 42.4s) |   C |   180 | 14.7 |        
    2989 | 2023-08-27 19:06:11 |      MASTER-Tavrida | (21h 12m 21.57s , -23d 54m 40.1s) |   C |   180 | 17.5 |        
    3151 | 2023-08-27 19:08:53 |   MASTER-Kislovodsk | (21h 22m 53.28s , -23d 47m 21.9s) |   C |   180 | 15.8 |        
    3151 | 2023-08-27 19:08:53 |   MASTER-Kislovodsk | (21h 22m 53.30s , -24d 11m 08.0s) |   C |   180 | 14.9 |        
    3179 | 2023-08-27 19:09:22 |      MASTER-Tavrida | (21h 12m 22.70s , -23d 53m 39.3s) |   C |   180 | 17.5 |        
    3351 | 2023-08-27 19:12:14 |   MASTER-Kislovodsk | (21h 22m 51.42s , -23d 45m 41.3s) |   C |   180 | 15.6 |        
    3352 | 2023-08-27 19:12:14 |   MASTER-Kislovodsk | (21h 22m 51.71s , -24d 09m 28.0s) |   C |   180 | 14.8 |        
    3368 | 2023-08-27 19:12:30 |      MASTER-Tavrida | (21h 12m 28.11s , -23d 54m 38.6s) |   C |   180 | 17.5 |        
    3552 | 2023-08-27 19:15:34 |   MASTER-Kislovodsk | (21h 22m 53.18s , -21d 47m 16.1s) |   C |   180 | 15.8 |        
    3552 | 2023-08-27 19:15:34 |   MASTER-Kislovodsk | (21h 22m 53.69s , -22d 10m 54.6s) |   C |   180 | 14.7 |        
    3555 | 2023-08-27 19:15:38 |      MASTER-Tavrida | (21h 12m 22.71s , -23d 55m 37.5s) |   C |   180 | 17.8 |        
    3744 | 2023-08-27 19:18:46 |      MASTER-Tavrida | (21h 12m 28.12s , -23d 55m 33.6s) |   C |   180 | 17.6 |        
    3933 | 2023-08-27 19:21:55 |      MASTER-Tavrida | (21h 12m 24.54s , -23d 53m 59.0s) |   C |   180 | 17.7 |        
    3953 | 2023-08-27 19:22:15 |   MASTER-Kislovodsk | (21h 22m 49.92s , -21d 46m 30.2s) |   C |   180 | 15.7 |        
    3953 | 2023-08-27 19:22:15 |   MASTER-Kislovodsk | (21h 22m 51.71s , -22d 10m 16.6s) |   C |   180 | 14.8 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB230827A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34581
SUBJECT: GRB 230827A: BALROG localization (Fermi Trigger  / GRB 230827762)
DATE:    23/08/27 20:59:21 GMT
FROM:    Jochen Greiner at MPE <jcgrog@mpe.mpg.de>

B. Biltzinger, T. Preis, J. Burgess & J. Greiner (all MPE Garching) report:

The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
 at 18:17:52 on 27 Aug. 2023 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) = 320.1+/-0.9 deg
Decl.(2000.0) = -20.3+/-0.9 deg
We estimate an additional systematic error of 1 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB230827762/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB230827762/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB230827762/json

                        


GRB_name: GRB230827A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34583
SUBJECT: GRB 230827A: GRBAlpha detection
DATE:    23/08/28 10:46:50 GMT
FROM:    Marianna DafÄÃ­kovÃ¡ at Masaryk University <500025@mail.muni.cz>

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

The long-duration GRB 230827A (Fermi/GBM detection: GCN 34575, INTEGRAL/SPI-ACS detection at 2023-08-27 ~18:17:53 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023; arXiv:2302.10048).

The detection was confirmed at the peak time 2023-08-27 18:18:14 UTC. The T90 duration measured by GRBAlpha is 73 s and the overall significance during T90 reaches 30 sigma.

The light curve obtained by GRBAlpha is available here: 
https://grbalpha.konkoly.hu/static/share/GRB230827A_GCN.pdf

All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/ 
GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume. 


GRB_name: GRB230827B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34584
SUBJECT: GRB 230827B / GRB 230827256: Fermi GBM Observation
DATE:    23/08/28 13:52:48 GMT
FROM:    rachel.hamburg@ijclab.in2p3.fr

R. Hamburg (CNRS/IJCLab) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 06:08:30.73 UT on 27 August 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230827B (trigger 714809315/230827256).
The optical afterglow of GRB 230827B was also detected by ZTF (GCN 34574),
GIT (GCN 34576), and AKO (GCN 34579). The location of the afterglow is 
consistent with the GBM on-ground calculated location, which is 
RA = 299.32, Dec = +56.47 (J2000 degrees, equivalent to 
J2000 19h 57m 17s, +56d 28' 12"), with a statistical 
uncertainty of 2.17 degrees.

The angle from the Fermi LAT boresight is 140 degrees.

The GBM light curve shows a multi-peaked lightcurve with a duration (T90)
of about 11 s (50-300 keV). The time-averaged spectrum
from T0+0.002 to T0+10.240 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.37 +/- 0.05 and the cutoff energy,
parameterized as Epeak, is 352 +/- 52 keV.
A Band function fits the spectrum equally well
with Epeak= 256 +/- 51 keV, alpha = -1.28 +/- 0.08 and beta = -2.2 +/- 0.2.

The event fluence (10-1000 keV) in this time interval is
(1.08 +/- 0.04)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+4.7 s in the 10-1000 keV band is 16.4 +/- 0.9 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: GRB230827B
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34585
SUBJECT: GRB 230827B: VZLUSAT-2 detection
DATE:    23/08/28 17:13:25 GMT
FROM:    Marianna DafÄÃ­kovÃ¡ at Masaryk University <500025@mail.muni.cz>

M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory),  N. Werner  (Masaryk U.), M. Ohno (Hiroshima U.),  L. Meszaros, B. Csak (Konkoly Observatory), H. Takahashi (Hiroshima U.), F. Munz , M. Topinka, F. Hroch, N. Husarikova, J.-P. Breuer (Masaryk U.), J. Hudec, J. Kapus, M. Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo (Needronix), G. Galgoczi (Wigner Research Center/Eotvos U.), N. Uchida (ISAS/JAXA), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. Hirose, H. Matake (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), K. Torigoe (Hiroshima U.), P. Svoboda, V. Daniel, J. Dudas, M. Junas, J. Gromes (VZLU), I. Vertat (FEL ZCU)  -- the VZLUSAT-2/GRB payload collaboration.

The long duration GRB 230827B (Fermi/GBM detection: GCN 34584; GECAM-B detection: trigger no. 215; CALET/CGBM detection: trigger no. 1377151581; INTEGRAL/SPI-ACS detection at 2023-08-27 ~06:08:31 UT) was detected by the GRB detectors on board of the VZLUSAT-2 3U CubeSat (https://www.vzlusat2.cz/en/).

The data acquisition was performed by the GRB detector units no. 0 and no. 1. The detection was confirmed at the peak time 2023-08-27 06:08:33 UTC. The T90 duration is 21 s (17 s) and the significance during T90 reaches 10.2 sigma (7.3 sigma) for detector unit no. 0 (no. 1).

The light curve obtained by VZLUSAT-2 is available here:
https://vzlusat2.konkoly.hu/static/share/GRB230827B_GCN_VZLUSAT2.pdf

All VZLUSAT-2 detections are listed at: https://monoceros.physics.muni.cz/hea/VZLUSAT-2/
The GRB detectors on VZLUSAT-2 are a demonstration payload for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). Two GRB modules of VZLUSAT-2 are placed in a perpendicular manner and each consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~30 keV to ~1000 keV. VZLUSAT-2 was launched on 2022 January 13 from Cape Canaveral.


GRB_name: GRB230826A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34586
SUBJECT: GRB 230826A: VZLUSAT-2 detection
DATE:    23/08/28 17:41:47 GMT
FROM:    Marianna DafÄÃ­kovÃ¡ at Masaryk University <500025@mail.muni.cz>

M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory),  N. Werner  (Masaryk U.), M. Ohno (Hiroshima U.),  L. Meszaros, B. Csak (Konkoly Observatory), H. Takahashi (Hiroshima U.), F. Munz , M. Topinka, F. Hroch, N. Husarikova, J.-P. Breuer (Masaryk U.), J. Hudec, J. Kapus, M. Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo (Needronix), G. Galgoczi (Wigner Research Center/Eotvos U.), N. Uchida (ISAS/JAXA), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. Hirose, H. Matake (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), K. Torigoe (Hiroshima U.), P. Svoboda, V. Daniel, J. Dudas, M. Junas, J. Gromes (VZLU), I. Vertat (FEL ZCU)  -- the VZLUSAT-2/GRB payload collaboration.

The long duration GRB 230826A (Fermi/GBM detection: GCN 34564; Swift/BAT detection: GCN 34565; GRBAlpha detection: GCN 34572) was detected by the GRB detectors on board of the VZLUSAT-2 3U CubeSat (https://www.vzlusat2.cz/en/).

The data acquisition was performed by the GRB detector units no. 0 and no. 1. The detection was confirmed at the peak time 2023-08-26 19:32:48 UTC. The T90 duration is 17 s (18 s) and the significance during T90 reaches 11 sigma (17 sigma) for detector unit no. 0 (no. 1).

The light curve obtained by VZLUSAT-2 is available here:
https://vzlusat2.konkoly.hu/static/share/GRB230826A_GCN_VZLUSAT2.pdf

All VZLUSAT-2 detections are listed at: https://monoceros.physics.muni.cz/hea/VZLUSAT-2/
The GRB detectors on VZLUSAT-2 are a demonstration payload for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). Two GRB modules of VZLUSAT-2 are placed in a perpendicular manner and each consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~30 keV to ~1000 keV. VZLUSAT-2 was launched on 2022 January 13 from Cape Canaveral.


GRB_name: GRB230827A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34587
SUBJECT: GRB 230827A: Swift/BAT-GUANO detection of a burst outside the coded FOV
DATE:    23/08/28 19:25:30 GMT
FROM:    Jimmy DeLaunay at University of Alabama  <delauj2@gmail.com>

James DeLaunay (U Alabama), Aaron Tohuvavohu (U Toronto), Samuele Ronchini (PSU), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report: 

Swift/BAT did not localize GRB 230827A onboard (T0: 2023-08-27T18:17:52.93 UTC, Fermi trig 714853077) 

The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). 

Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 90 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. 

The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 54.6 in a 8.192 s analysis time bin, starting at T0 + 18.432 s. 

NITRATES results are consistent with a burst coming from outside the FOV, with DeltaLLHOut of -61 and are consistent with Fermi GBM's localization (GCN 34575).

See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut. 

GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. 

A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/


GRB_name: GRB230827A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34588
SUBJECT: GRB 230827A: VZLUSAT-2 detection
DATE:    23/08/28 20:31:23 GMT
FROM:    Marianna DafÄÃ­kovÃ¡ at Masaryk University <500025@mail.muni.cz>

M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory),  N. Werner  (Masaryk U.), M. Ohno (Hiroshima U.),  L. Meszaros, B. Csak (Konkoly Observatory), H. Takahashi (Hiroshima U.), F. Munz , M. Topinka, F. Hroch, N. Husarikova, J.-P. Breuer (Masaryk U.), J. Hudec, J. Kapus, M. Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo (Needronix), G. Galgoczi (Wigner Research Center/Eotvos U.), N. Uchida (ISAS/JAXA), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. Hirose, H. Matake (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (Univ of Tokyo), K. Torigoe (Hiroshima U.), P. Svoboda, V. Daniel, J. Dudas, M. Junas, J. Gromes (VZLU), I. Vertat (FEL ZCU)  -- the VZLUSAT-2/GRB payload collaboration.

The long duration GRB 230827A (Fermi/GBM detection: GCN 34575; GRBAlpha detection: GCN 34583; Swift/BAT-GUANO detection: GCN 34587; INTEGRAL/SPI-ACS detection at 2023-08-27 ~18:17:53 UT) was detected by the GRB detectors on board of the VZLUSAT-2 3U CubeSat (https://www.vzlusat2.cz/en/).

The data acquisition was performed by the GRB detector units no. 0 and no. 1. The detection was confirmed at the peak time 2023-08-27 18:18:09 (18:18:18) UTC. The T90 duration is 82 s (77 s) and the significance during T90 reaches 10 sigma (24 sigma) for detector unit no. 0 (no. 1).

The light curve obtained by VZLUSAT-2 is available here:
https://vzlusat2.konkoly.hu/static/share/GRB230827A_GCN_VZLUSAT2.pdf

All VZLUSAT-2 detections are listed at: https://monoceros.physics.muni.cz/hea/VZLUSAT-2/
The GRB detectors on VZLUSAT-2 are a demonstration payload for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). Two GRB modules of VZLUSAT-2 are placed in a perpendicular manner and each consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~30 keV to ~1000 keV. VZLUSAT-2 was launched on 2022 January 13 from Cape Canaveral.


GRB_name: GRB230828A
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34590
SUBJECT: GRB 230828A: GRBAlpha detection
DATE:    23/08/29 11:14:43 GMT
FROM:    Marianna DafÄÃ­kovÃ¡ at Masaryk University <500025@mail.muni.cz>

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

The long-duration GRB 230828A (AstroSat trigger at 2023-08-28 16:29:43 UT, INTEGRAL/SPI-ACS detection at 2023-08-28 ~16:28:55 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023; arXiv:2302.10048).

The detection was confirmed at the peak time 2023-08-28 16:29:53 UTC. The T90 duration measured by GRBAlpha is 140 s and the overall significance during T90 reaches 27 sigma.

The light curve obtained by GRBAlpha is available here: 
https://grbalpha.konkoly.hu/static/share/GRB230828A_GCN.pdf

All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/ 
GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume. 


GRB_name: GRB230828A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34591
SUBJECT: GRB 230828A: AstroSat CZTI detection
DATE:    23/08/29 12:00:17 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

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

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 230828A which was also detected by GRBAlpha (Dafcikova et al., GCN Circ. 34590).

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 2023-08-28 16:28:57.50 UTC. The measured peak count rate associated with the burst is 152 (+47, -8) counts/s above the background in the combined data of all quadrants, with a total of 4190 (+848, -887) counts. The local mean background count rate was 434 (+2, -2) counts/s. Using cumulative rates, we measure a T90 of 142 (+18, -22) s.

The source 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 2023-08-28 16:29:43.14 UTC. The measured peak count rate associated with the burst is 410 (+75, -17) counts/s above the background in the combined data of all quadrants, with a total of 10117 (+1492, -1750) counts. The local mean background count rate was 1341 (+3, -4) counts/s. We measure a T90 of 123 (+10, -6) s from the cumulative Veto light curve.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at: 
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230826A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34592
SUBJECT: GRB 230826A: Swift-BAT refined analysis
DATE:    23/08/29 15:27:50 GMT
FROM:    Tyler Parsotan  at NASA GSFC <tyler.parsotan@nasa.gov>

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


Using the data set from T-61 to T+1091 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 230826A (trigger #1187463)
(Eyles-Ferris, et al., GCN Circ. 34565). The BAT ground-calculated position is
RA, Dec = 83.048, 66.129 deg which is
RA(J2000) = 05h 32m 11.5s
Dec(J2000) = +66d 07' 43.9"
with an uncertainty of 1.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 87%.


The mask weighted light curve shows two main emission episodes where the first has
enhanced structure. T90 (15-350 keV) is 41.07 +- 2.36 sec (estimated error including systematics).


The time-averaged spectrum from T-4.26 to T+56.79 sec is best fit by a power law
with an exponential cutoff. This fit gives a photon index 1.20 +- 0.22,
and Epeak of 122.3 +- 70.2 keV (chi squared 44.78 for 56 d.o.f.). For this
model the total fluence in the 15-150 keV band is 3.6 +- 0.1 x 10^-06 erg/cm2
and the 1-sec peak flux measured from T+2.44 sec in the 15-150 keV band is
3.0 +- 0.2 ph/cm2/sec. A fit to a simple power law gives a photon index
of 1.55 +- 0.05 (chi squared 52.29 for 57 d.o.f.). 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/1187463/BA/ <http://gcn.gsfc.nasa.gov/notices_s/1187463/BA/>


GRB_name: GRB230827B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34593
SUBJECT: GRB 230827B: CALET Gamma-Ray Burst Monitor detection
DATE:    23/08/29 15:56:27 GMT
FROM:    Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>

T. Tamura (Kanagawa U), A. Yoshida, T. Sakamoto, S. Sugita (AGU), 
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA),
Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U),
Y. Shimizu (Kanagawa U), N. Cannady (GSFC/UMBC),
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The long GRB 230827B (Fermi GBM Observation: Hamburg et al.,
GCN Circ. 34584; VZLUSAT-2 detection: Dafcikova et al., GCN 
Circ. 34585) triggered the CALET Gamma-ray Burst Monitor (CGBM)
at 06:08:28.36 UTC on 27 July 2023
(http://cgbm.calet.jp/cgbm_trigger/flight/1377151581/).
The burst signal was seen by only the SGM detector.

The burst light curve shows a multi-peaked structure that starts
at T+2.3 sec, peaks at T+2.7 sec, and ends at T+87.7 sec.
The T90 and T50 durations measured by the SGM data are 79.6 +/- 3.7 sec
and 57.4 +/- 2.5 sec (40-1000 keV), respectively.

The ground-processed light curve is available at

 http://cgbm.calet.jp/cgbm_trigger/ground/1377151581/

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


GRB_name: GRB230827A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34594
SUBJECT: GRB 230827A: Fermi GBM Observation
DATE:    23/08/29 18:29:51 GMT
FROM:    Lorenzo Scotton at UAH <lscottongcn@outlook.com>

L. Scotton (UAH), C. Fletcher (USRA) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 18:17:52.93 UT on 27 August 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230827A (trigger 714853077/230827762).
which was also detected by GRBAlpha (Dafcikova et al. 2023, GCN 34583) 
and Swift/BAT GUANO (DeLaunay et al. 2023, GCN 34587).
The Fermi GBM Final Real-time Localization was reported in GCN 34575. 

The angle from the Fermi LAT boresight is 95 degrees.

The GBM light curve consists of multiple peaks with a duration (T90)
of about 83 s (50-300 keV). The time-averaged spectrum
from T0-1.2 to T0+85.9 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.96 +/- 0.03 and the cutoff energy,
parameterized as Epeak, is 415 +/- 26 keV.

The event fluence (10-1000 keV) in this time interval is
(3.58 +/- 0.08)E-05 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+21 s in the 10-1000 keV band is 10.7 +/- 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: GRB230827B
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34596
SUBJECT: GRB 230827B: Swift ToO observations
DATE:    23/08/29 22:31:52 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

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

Swift has initiated a ToO observation of the Fermi/GBM GRB 230827B. 
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021620

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Fermi/GBM 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: GRB230812B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34597
SUBJECT: GRB 230812B: Spectroscopic detection of the associated SN 2023pel.
DATE:    23/08/29 22:49:42 GMT
FROM:    J. F. Agui Fernandez at IAA-CSIC <feli@iaa.es>

J. F. Agui Fernandez (IAA-CSIC), A. de Ugarte Postigo (OCA-CNRS), C. C. Thoene (ASU-CAS), D. B. Malesani (Radboud and DAWN/NBI), L. Izzo (INAF-OACN and DARK/NBI) and A. L. Cabrera Lavers (GTC, IAC) report:

We observed the long GRB 230812B*/*SN 2023pel (Fermi GBM Team GCN, 34386; Roberts et al. GCN34391, Scotton et al. GCN 34392, Zheng & Filippenko GCN 34395, Beardmore et al. GCN 34400) on August 24, 2023 at 21.79 hours UT, ~12.12 days after the GRB detection, with OSIRIS+ in spectroscopy mode at the 10.4m GTC Telescope located at Roque de los Muchachos, Canary Islands, Spain. The spectrum covers the wavelength range from 3700 to 7500 AA. In a preliminary analysis, the spectrum shows the characteristic undulations of a GRB-SN spectrum. Our spectrum is well matched to the spectrum of SN 1998bw at a comparable rest-frame epoch (Patat et al. 2001, ApJ, 555, 900). We can thus conclusive determine the presence of a SN associated with GRB 230812B, confirming previous claims based on photometric evidence (Moskvitin & Spiridonova GCN 34475, Moskvitin & Goranskij GCN 34496, Kumar et al. GCN 34500, Turpin et al. GCN 34508, Kumar et al. GCN 34516, Pankov et al. GCN 34519).

We acknowledge excellent support from the GTC staff.


GRB_name: GRB230827B
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34601
SUBJECT: GRB 230827B: Swift-XRT afterglow detection
DATE:    23/08/30 13:26:29 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

A. Tohuvavohu (U. Toronto), J.P. Osborne (U. Leicester), K.L. Page (U.
Leicester), A.P. Beardmore (U. Leicester), M. Perri (SSDC & INAF-OAR),
V. D'Elia (SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), D.N. Burrows
(PSU), J. D. Gropp (PSU) and P.A. Evans (U. Leicester) reports on
behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Fermi/GBM-detected burst GRB 230827B (GCN Circ. 34584), collecting 3.6
ks of Photon Counting (PC) mode data between T0+231.3 ks and T0+249.7
ks. 

An uncatalogued X-ray source is detected consistent with being within
9.9 arcsec of the position of ZTF23abaanxz/AT2023qxj (GCN Circ. 34574)
and is believed to be the afterglow. Using 3821 s of PC mode data and 4
UVOT images, we find an enhanced XRT position (using the XRT-UVOT
alignment and matching UVOT field sources to the USNO-B1 catalogue):
RA, Dec = 299.63944, +54.46318 which is equivalent to:

RA (J2000): 19h 58m 33.47s
Dec(J2000): +54d 27' 47.5"

with an uncertainty of 2.6 arcsec (radius, 90% confidence). This
position is 0.8 arcsec from the ZTF position.  The light curve is
consistent with a constant source of mean count rate 7.0e-02 ct/sec. A
power-law fit gives an index of 2.490 (+0.015, -2.990).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.59 (+0.33, -0.30). The
best-fitting absorption column is  4.0 (+2.1, -1.0) x 10^21 cm^-2,
consistent with the Galactic value of 3.0 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 5.0 x 10^-11 (6.4 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      4.0 (+2.1, -1.0) x 10^21 cm^-2
Galactic foreground: 3.0 x 10^21 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.59 (+0.33, -0.30)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00021620.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/00021620.

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


GRB_name: GRB230826A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34602
SUBJECT: GRB 230826A: Glowbug gamma-ray detection
DATE:    23/08/30 14:50:37 GMT
FROM:    matthew.kerr@gmail.com

M. Kerr, C.C. Cheung, J. E. Grove, R. Woolf (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge (MSFC), and M.S. Briggs (UAH) report:

The Glowbug gamma-ray telescope [1,2], operating on the International Space Station, reports the detection of GRB 230826A, which was also detected by Fermi/GBM, Swift/BAT, GRBAlpha, and VZLUSAT-2 (GCN 34564, 34565, 34572, 34586).

Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2023-08-26 19:32:44.336 with a duration of 12.3 s and a total significance of about 29.9 sigma. The light curve comprises a single peak.

Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission over this duration results in a poorly constrained power-law index and a cutoff energy ("Epeak") of 138 keV. The modeled 10-10000 keV fluence is 1.5e-06 erg/cm^2.

The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.

Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC. It was launched on 2023 March 15 aboard the Department of Defense Space Test Programâ€™s STP-H9 to the ISS. The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.

[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006

Distribution Statement A: Approved for public release. Distribution is unlimited.


GRB_name: GRB230827A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34603
SUBJECT: GRB 230827A: Glowbug gamma-ray detection
DATE:    23/08/30 14:50:54 GMT
FROM:    matthew.kerr@gmail.com

M. Kerr, C.C. Cheung, J. E. Grove, R. Woolf (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge (MSFC), and M.S. Briggs (UAH) report:

The Glowbug [1,2] gamma-ray telescope, operating on the International Space Station, reports the detection of GRB 230827A, which was also detected by Fermi/GBM, GRBAlpha, Swift/BAT-GUANO, VZLUSAT-2, and INTEGRAL/SPI-ACS (GCN 34575, 34583, 34587, 34588).

Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2023-08-27 18:17:50.272 with a duration of 100.4 s and a total significance of about 78.2 sigma.  The light curve comprises two broad peaks each of about 50s duration, with the peak flux observed roughly at the center of the first pulse.

Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission over this duration results in a photon index dN/dE~E^x of x=-0.5 and a cutoff energy ("Epeak") of 371 keV.  The modeled 10-10000 keV fluence is 2.9e-05 erg/cm^2.

The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.

Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC.  It was launched on 2023 March 15 aboard the Department of Defense Space Test Programâ€™s STP-H9 to the ISS.  The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.

[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006

Distribution Statement A: Approved for public release.  Distribution is unlimited.


GRB_name: GRB230827B
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34604
SUBJECT: GRB 230827B: Glowbug gamma-ray detection
DATE:    23/08/30 14:51:11 GMT
FROM:    matthew.kerr@gmail.com

M. Kerr, C.C. Cheung, J. E. Grove, R. Woolf (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge (MSFC), and M.S. Briggs (UAH) report:

The Glowbug [1,2] gamma-ray telescope, operating on the International Space Station, reports the detection of GRB 230827B, which was also detected by Fermi/GBM, VZLUSAT-2, GECAM-B (trigger 215), INTEGRAL/SPI-ACS, and CALET (GCN 34584, 34585, 34593).

Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2023-08-27 06:08:30.320 with a duration of 10.6 s and a total significance of about 57.8 sigma.  The light-curve comprises two similar FRED pulses with widths of about 1s, separated by about 5s, each with tails of faint emission lasting about 5s.

Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission over this duration results in a photon index dN/dE~E^x of x=0.4 and a cutoff energy ("Epeak") of 272 keV.  The modeled 10-10000 keV fluence is 1.3e-05 erg/cm^2.

The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.

Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC.  It was launched on 2023 March 15 aboard the Department of Defense Space Test Programâ€™s STP-H9 to the ISS.  The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.

[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006

Distribution Statement A: Approved for public release.  Distribution is unlimited.


GRB_name: GRB230903A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34608
SUBJECT: GRB 230903A: Fermi GBM Final Real-time Localization
DATE:    23/09/03 17:33:32 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

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

At 17:22:58 UT on 3 Sep 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230903A (trigger 715454583.81493 / 230903724).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 13.4, Dec = -13.5 (J2000 degrees, equivalent to J2000 00h 53m, -13d 30'), with a statistical uncertainty of 16.6 degrees.

The angle from the Fermi LAT boresight is 70.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230903724/quicklook/glg_skymap_all_bn230903724.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230903724/quicklook/glg_healpix_all_bn230903724.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230903724/quicklook/glg_lc_medres34_bn230903724.gif


GRB_name: GRB230903A
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34610
SUBJECT: GRB 230903A: Swift detection of a burst
DATE:    23/09/03 17:46:24 GMT
FROM:    K.L. Page at U Leicester <klp5@leicester.ac.uk>


A. D'Ai (INAF-IASFPA), E. Ambrosi (INAF-IASFPA), J.D. Gropp (PSU),
J. A. Kennea (PSU), A. Y. Lien (U Tampa), A. Melandri (INAF-OAR),
M. J. Moss (GWU), D. M. Palmer (LANL) and A. Tohuvavohu (U Toronto)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 17:22:56 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230903A (trigger=1189514).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 9.926, -40.924 which is 
   RA(J2000) = 00h 39m 42s
   Dec(J2000) = -40d 55' 25"
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 10 sec.  The peak count rate
was ~1500 counts/sec (15-350 keV), at ~1 sec after the trigger. 

The XRT began observing the field at 17:24:47.9 UT, 111.7 seconds after
the BAT trigger. Using promptly downlinked data we find a fading,
uncatalogued X-ray source with an enhanced position: RA, Dec 9.91169,
-40.94930 which is equivalent to:
   RA(J2000)  = 00h 39m 38.81s
   Dec(J2000) = -40d 56' 57.5"
with an uncertainty of 1.9 arcseconds (radius, 90% containment). This
location is 99 arcseconds from the BAT onboard position, within the BAT
error circle. This position may be improved as more data are received;
the latest position is available at https://www.swift.ac.uk/sper. 

A power-law fit to a spectrum formed from promptly downlinked event
data gives a column density in excess of the Galactic value (2.68 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 2.6
(+2.17/-1.93) x 10^21 cm^-2 (90% confidence). 

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

Burst Advocate for this burst is A. D'Ai (antonino.dai 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: GRB230903A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34611
SUBJECT: GRB 230903A: LCOGT Optical Upper Limits
DATE:    23/09/03 22:06:53 GMT
FROM:    Robert Strausbaugh at Eastern Illinois University <rstrausbaugh@eiu.edu>

R. Strausbaugh (Eastern Illinois University), A. Cucchiara (NASA) report on behalf of a larger collaboration:

We observed the Swift GRB 230903A (D'ai et al., GCN 34610) field with the LCOGT 1-meter Sinistro instrument at the South African Astronomical Observatory site, on September 3,  from 20:08 to 20:41 UT (corresponding to 2.77 to 3.32 hours from the GRB trigger time) with the Bessel R and I filters.

We performed a series of 3x300s exposures in each band.  We do not detect a source within the Swift-XRT error region (D'Ai et al., GCN 34610) in either band.

The following upper limits are calculated using the USNO-B1.0 catalog as reference:

R > 20.5
I > 19.0

These magnitudes are not corrected for galactic extinction.


GRB_name: GRB230904A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34614
SUBJECT: Fermi GRB 230904A: Global MASTER-Net observations report
DATE:    23/09/04 11:30:48 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik,  D. Vlasenko,
G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij
(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. Gress, N.M. Budnev, O.Ershova
(Irkutsk State University, API),

L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez
(INAOE, Guillermo Haro Astrophysics Observatory),

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

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

MASTER-Amur robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Blagoveshchensk State Pedagogical University) started inspect of the Fermi GRB 230904A ( Fermi GBM team, GCN 34613) errorbox  10127 sec after notice time and 10162 sec after trigger time at 2023-09-04 11:08:53 UT, with upper limit up to  17.4 mag. Observations started at twilight.  The observations began at zenith distance = 49 deg. The sun  altitude  is -9.8 deg. 

The galactic latitude b = -6 deg., longitude l = 13 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2265350

We obtain a following upper limits.  

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

   10192 | 2023-09-04 11:08:53 |         MASTER-Amur | (18h 25m 07.20s , +01d 19m 23.3s) |   C |    60 | 17.1 |        
   10366 | 2023-09-04 11:11:47 |         MASTER-Amur | (18h 32m 59.20s , +01d 19m 54.6s) |   C |    60 | 17.1 |        
   10463 | 2023-09-04 11:13:23 |         MASTER-Amur | (18h 43m 34.46s , +01d 00m 41.9s) |   C |    60 | 17.4 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB230904B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34615
SUBJECT: GRB 230904B: BALROG localization (Fermi Trigger 715526984 / GRB 230904562)
DATE:    23/09/04 14:01:47 GMT
FROM:    Jochen Greiner at MPE <jcgrog@mpe.mpg.de>

T. Preis, B. Biltzinger, J. Burgess & J. Greiner (all MPE Garching) report:

The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
715526984 at 13:29:39 on 04 Sept. 2023 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) = 20.8+/-2.4 deg
Decl.(2000.0) = -26.7+/-0.9 deg
We estimate an additional systematic error of 2 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB230904562/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB230904562/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB230904562/json

                        


GRB_name: GRB230904B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34617
SUBJECT: GRB 230904B is not a GRB
DATE:    23/09/04 16:39:00 GMT
FROM:    Oliver J Roberts at USRA/NASA <oliver.roberts@nasa.gov>

Subject: GRB 230904B is not a GRB

O.J. Roberts (USRA) and S. Bala (USRA), report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"The Fermi Gamma-ray Burst Monitor (GBM) trigger 715526984/230904562 at 13:29:39.52 UT
on 04 September 2023, previously named as GRB 230904B (GCN 34615), is in fact not due
to a GRB. This trigger is due to particle activity."


GRB_name: GRB230903A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34618
SUBJECT: GRB 230903A: Fermi GBM detection
DATE:    23/09/04 16:40:58 GMT
FROM:    Oliver J Roberts at USRA/NASA <oliver.roberts@nasa.gov>

O.J. Roberts (USRA), B. Mailyan (Florida Tech) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 17:22:58.81 UT on the 3rd September 2023 , the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 230903A (trigger 715454583 / 230903724) which was also detected 
by the Swift/BAT (A. D'ai et al. 2023, GCN 34610). The Fermi GBM Final Real-time Localization 
(GCN 34608) is consistent with the Swift position.

The angle from the Fermi LAT boresight at the GBM trigger time is 98 degrees.

The GBM light curve consists of one pulse
with a duration (T90) of about 3 s (50-300 keV).
The time-averaged spectrum from T0-4.0 s to T0+1.0 s is
best fit by a simple power law function with index -1.78 +/- 0.09.

A power law function with an exponential high-energy cutoff fits
the spectrum equally well. The power law index is -1.27 +/- 0.33 
and the cutoff energy, parameterized as Epeak, is 95 +/- 31 keV.

The event fluence (10-1000 keV) in this time interval is
(5.87 +/- 0.85)E-07 erg/cm^2. The 1-sec peak photon flux measured
starting from T0-1s in the 10-1000 keV band
is 2.0 +/- 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: GRB230903A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34619
SUBJECT: Fermi GRB 230903A: Global MASTER-Net observations report
DATE:    23/09/04 19:31:00 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik,  D. Vlasenko,
G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij
(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. Gress, N.M. Budnev, O.Ershova
(Irkutsk State University, API),

L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez
(INAOE, Guillermo Haro Astrophysics Observatory),

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

V. Yurkov, A. Gabovich
(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 230903A ( Fermi GBM team, GCN 34608) errorbox  49439 sec after notice time and 49475 sec after trigger time at 2023-09-04 07:07:34 UT, with upper limit up to  18.3 mag. The observations began at zenith distance = 24 deg. The sun  altitude  is -47.1 deg. 

MASTER-Amur robotic telescope  located in Russia (Blagoveshchensk State Pedagogical University) started inspect of the Fermi GRB 230903A errorbox  83217 sec after notice time and 83253 sec after trigger time at 2023-09-04 16:30:32 UT, with upper limit up to  16.5 mag. The observations began at zenith distance = 50 deg. The sun  altitude  is -31.3 deg. 

The galactic latitude b = -76 deg., longitude l = 128 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2264968

We obtain a following upper limits.  

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

   49505 | 2023-09-04 07:07:34 |         MASTER-OAFA | (23h 45m 07.73s , -21d 40m 56.2s) |   C |    60 | 18.3 |        
   50337 | 2023-09-04 07:21:25 |         MASTER-OAFA | (23h 45m 12.23s , -21d 40m 04.4s) |   C |    60 | 18.3 |        
   83283 | 2023-09-04 16:30:32 |         MASTER-Amur | (00h 45m 02.38s , +01d 03m 22.9s) |   C |    60 | 16.4 |        
   83363 | 2023-09-04 16:31:51 |         MASTER-Amur | (00h 52m 59.10s , +01d 05m 05.8s) |   C |    60 | 16.5 |        
   83442 | 2023-09-04 16:33:11 |         MASTER-Amur | (00h 44m 55.77s , +02d 58m 32.3s) |   C |    60 | 16.5 |        
   83522 | 2023-09-04 16:34:30 |         MASTER-Amur | (00h 52m 50.71s , +02d 58m 14.6s) |   C |    60 | 16.2 |        
   83941 | 2023-09-04 16:41:29 |         MASTER-Amur | (00h 44m 58.62s , +01d 04m 26.3s) |   C |    60 | 16.2 |        
   84021 | 2023-09-04 16:42:49 |         MASTER-Amur | (00h 52m 58.54s , +01d 03m 22.6s) |   C |    60 | 16.2 |        
   84100 | 2023-09-04 16:44:08 |         MASTER-Amur | (00h 44m 54.16s , +02d 58m 06.4s) |   C |    60 | 16.2 |        
   84180 | 2023-09-04 16:45:28 |         MASTER-Amur | (00h 52m 50.10s , +02d 57m 42.0s) |   C |    60 | 15.9 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB230904C
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34622
SUBJECT: GRB 230904C: Fermi GBM Final Localization
DATE:    23/09/04 23:32:23 GMT
FROM:    Sarah Dalessi at UAH <sd0104@uah.edu>

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

"At 20:28:02.19 UT on 04 September 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230904C (trigger 715552087/230904853).

The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 127.66, Dec = 55.24 (J2000 degrees, equivalent to J2000 12h 28m, +55d 24'),
with a statistical uncertainty of 3.92 degrees.

The angle from the Fermi LAT boresight is 29 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230904853/quicklook/glg_skymap_all_bn230904853.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230904853/quicklook/glg_healpix_all_bn230904853.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230904853/quicklook/glg_lc_medres34_bn230904853.gif"


GRB_name: GRB230903A
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34623
SUBJECT: GRB 230903A: Swift-BAT refined analysis
DATE:    23/09/05 04:07:26 GMT
FROM:    Mike Moss at George Washington U <mikejmoss3@gmail.com>

M. J. Moss (GSFC),
S. D. Barthelmy (GSFC), 
A. D'Ai (INAF-IASFPA),
H. A. Krimm (NSF),
S. Laha (GSFC/UMBC),
A. Y. Lien (U Tampa),
C. B. Markwardt (GSFC),
D. M. Palmer (LANL),
T. Parsotan (GSFC/UMBC),
T. Sakamoto (AGU),
M. Stamatikos (OSU)
(i.e. the Swift-BAT team):
 
Using the data set from T-239 to T+963 sec from the recent telemetry downlink,
we report further analysis of BAT GRB 230903A (trigger #1189514)
(D'Ai, et al., GCN Circ. 34610).  The BAT ground-calculated position is
RA, Dec = 9.898, -40.910 deg which is 
   RA(J2000)  =  00h 39m 35.5s 
   Dec(J2000) = -40d 54' 34.5" 
with an uncertainty of 1.9 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 40%.
 
The mask weighted light curve shows a single short pulse. T90 (15-350 keV) is 2.54 +- 0.27 sec (estimated error including systematics). 
The T90 and the spectral hardness of this burst places it on the border of the long-soft and hard-short burst classifications. 
 
The time-averaged spectrum from T+0.20 to T+2.93 sec is best fit by a power law
with an exponential cutoff.  This fit gives a photon index -0.66 +- 1.49, 
and Epeak of 63.4 +- 17.8 keV (chi squared 44.41 for 56 d.o.f.).  For this
model the total fluence in the 15-150 keV band is 2.2 +- 0.4 x 10^-07 erg/cm2
and the 1-sec peak flux measured from T+0.50 sec in the 15-150 keV band is
1.3 +- 0.3 ph/cm2/sec.  A fit to a simple power law gives a photon index
of 1.40 +- 0.21 (chi squared 54.66 for 57 d.o.f.).  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/1189514/BA/


GRB_name: GRB230903A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34624
SUBJECT: GRB 230903A: VLT/X-shooter optical observations
DATE:    23/09/05 10:07:06 GMT
FROM:    Emeric Le Floc'h at CEA-Saclay <emeric.lefloch@cea.fr>

D. Pieterse (Radboud University), D. B. Malesani (Radboud and DAWN/NBI), E. Le Flocâ€™h (CEA-Saclay), A. Saccardi (GEPI, Obs. de Paris) and N. R. Tanvir (Univ. of Leicester) report on behalf of the Stargate collaboration :

We observed the field of GRB230903A (Fermi GBM team, GCN 34608 ; Dâ€™Ai et al., GCN 34610) using the ESO VLT UT3 (Melipal) equipped with the X-shooter instrument. Three 60s exposures were obtained in the r-band on 2023 September 4.097 UT (T-To ~8.95h). The observations were performed under poor weather conditions, with a seeing of 3.2 arcsec measured in the data. We do not detect any source coinciding with the location of the X-ray afterglow detected by Swift/XRT (Dâ€™Ai et al., GCN 34610). We obtain the following upper limit, calibrated using a faint, nearby object from the Legacy Survey (Dey et al. 2019, ApJ, 257, 29).

r > 22.7 mag (AB)

This estimate is not corrected for Galactic extinction and is consistent with the non-detection reported earlier by LCOGT (Strausbaugh et al., GCN 34611).

We acknowledge excellent support from the ESO observing staff in Paranal, in particular Claudia Paladini and Jonathan Smoker.


GRB_name: GRB230903A
Detection_method: Swift-XRT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34625
SUBJECT: GRB 230903A: Enhanced Swift-XRT position
DATE:    23/09/05 12:44:15 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.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 832 s of XRT Photon Counting mode data and 2 UVOT
images for GRB 230903A, 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 = 9.91061, -40.95001 which is equivalent
to:

RA (J2000): 00h 39m 38.55s
Dec (J2000): -40d 57' 00.0"

with an uncertainty of 2.2 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: GRB230903A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34626
SUBJECT: GRB 230903A: Swift-XRT refined Analysis
DATE:    23/09/05 14:09:08 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

K.L. Page (U. Leicester), A.P. Beardmore (U. Leicester), V. D'Elia
(SSDC & INAF-OAR), B. Sbarufatti (INAF-OAB), A. D'Ai (INAF-IASFPA),
D.N. Burrows (PSU), J. D. Gropp (PSU), S. Dichiara (PSU) and P.A. Evans
report on behalf of the Swift-XRT team:

We have analysed 2.3 ks of XRT data for GRB 230903A, from 97 s to 29.3
ks after the  BAT trigger. The data comprise 8 s in Windowed Timing
(WT) mode (taken while Swift was slewing), with the remainder in Photon
Counting (PC) mode. 

The light curve can be modelled with a power-law decay with a decay
index of alpha=1.17 (+/-0.09).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 2.00 (+0.24, -0.22). The
best-fitting absorption column is  8.2 (+5.9, -5.0) x 10^20 cm^-2, in
excess of the Galactic value of 2.7 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 3.3 x 10^-11 (3.9 x 10^-11) erg
cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      8.2 (+5.9, -5.0) x 10^20 cm^-2
Galactic foreground: 2.7 x 10^20 cm^-2
Excess significance: 1.8 sigma
Photon index:      2.00 (+0.24, -0.22)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01189514.

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


GRB_name: GRB230905A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34628
SUBJECT: GRB 230905A: Fermi GBM Final Real-time Localization
DATE:    23/09/05 15:55:23 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

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

At 15:44:59 UT on 5 Sep 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230905A (trigger 715621504.769918 / 230905656).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 154.8, Dec = -0.8 (J2000 degrees, equivalent to J2000 10h 19m, 0d 48'), with a statistical uncertainty of 14.4 degrees.

The angle from the Fermi LAT boresight is 64.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230905656/quicklook/glg_skymap_all_bn230905656.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230905656/quicklook/glg_healpix_all_bn230905656.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230905656/quicklook/glg_lc_medres34_bn230905656.gif


GRB_name: GRB230905B
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34630
SUBJECT: GRB 230905B: GECAM-C detection of a long burst
DATE:    23/09/06 13:43:51 GMT
FROM:    yqzhang_cl@163.com

Shaolin Xiong, Wangchen Xue, Yue Huang report on behalf of the GECAM team:

GECAM-C was triggered in-flight by a long burst, GRB 230905B,
at 2023-09-05T15:49:35.850, which was also observed by INTEGRAL/SPI-ACS.

According to the realtime alert data of GECAM-C, this burst
mainly consists of a long pulse with a duration (T90) of about ~10 sec (20-1000 keV).

Using the automatic on-ground localization pipeline with the realtime alert data, 
GECAM-C localized this burst to the following position (J2000): 
RA: 340.1 deg 
DEC: 9.2 deg
Err: 5.2 deg (1-sigma, statistical only)
The systematic error of this location is estimated to be several degrees.

The time-averaged spectrum of GECAM-C realtime data shows that it could be
adequately fit by a cut-off power-law with a fluence about 2.7E-6 erg/cm^2 in 20-1000 keV. 

We note that these results are based on realtime alert data and thus very preliminary. 
Refined analysis will be reported later.

Gravitational wave high-energy Electromagnetic Counterpart All-sky Monitor
(GECAM) mission originally consists of two microsatellites (GECAM-A and GECAM-B)
launched in Dec. 2020. As the third member of GECAM constellation, 
GECAM-C was launched onboard SATech-01 experimental satellite in July 2022. 
GECAM mission is funded by the Chinese Academy of Sciences (CAS).


GRB_name: GRB230906A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34631
SUBJECT: GRB 230906A: Fermi GBM Final Localizationn
DATE:    23/09/06 15:07:02 GMT
FROM:    Elisabetta Bissaldi at Politecnico and INFN Bari <elisabetta.bissaldi@ba.infn.it>

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

"At 12:55:07.15 UT on 06 September 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230906A (trigger 715697712/230906538).

The on-ground calculated location, using the Fermi GBM trigger data,
is RA = 81.37, Dec = -47.41 (J2000 degrees, equivalent to J2000 05h 25m, -47d 24'),
with a statistical uncertainty of 2.79 degrees.

The angle from the Fermi LAT boresight is 55.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230906538/quicklook/glg_skymap_all_bn230906538.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230906538/quicklook/glg_healpix_all_bn230906538.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230906538/quicklook/glg_lc_medres34_bn230906538.gif  "


GRB_name: GRB230812B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34632
SUBJECT: GRB 230812B: Chandra late-time detection of the X-ray afterglow
DATE:    23/09/06 17:17:12 GMT
FROM:    Utkarsh Pathak at IIT Bombay <utkarshpathak.07@gmail.com>

U. Pathak (IITB), A. Salgundi (IITB), G. Waratkar  (IITB), V. Swain  (IITB), V. Bhalerao (IITB), B. Cenko (UMD), G. Dewangan (IUCAA), T. Ahumada (UMD), I. Andreoni (UMCP), G C Anupama (IIA), D. Bhattacharya (IUCAA), A. Jaodand (CIT), M. Kasliwal (CIT), D. Perley (LJMU), G. Srinivasaragavan (UMCP), P. Chandra (NRAO) report on behalf of a larger collaboration

We carried out a Chandra DDT observation of GRB 230812B beginning on September 3, 2023, at 01:04:23 UT with ACIS-S as part of program 24408929 (PI: Pathak) for 21.39 ks. The observation began ~21.25 days after the GRB trigger. 

Within the XRT localization (Page et al., GCN Circ. 34394), we detect a single point source at RA, DEC = 16:36:31.5221, 47:51:32.353 with an uncertainty of 0.4" from ZTF candidate afterglow (Salgundi et al., GCN Circ. 34397). The Chandra detection is consistent with decay rate as seen in XRT afterglow (Beardmore et al., GCN Circ. 34400) and the calculated absorbed flux for 0.3-10 keV is 7.33 (-1.35, +1.55) x 10^(-14) erg cm^-2 s^-1.

We thank the CXO staff - in particular Patrick Slane, Dan Schwartz, Harvey Tananbaum, Steiner James, Doug Swartz, and Malgorzata Sobolewska for rapidly approving and planning this observation.


GRB_name: GRB230906A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34634
SUBJECT: Fermi GRB 230906A: Global MASTER-Net observations report
DATE:    23/09/07 03:30:54 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik,  D. Vlasenko,
G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij
(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. Gress, N.M. Budnev, O.Ershova
(Irkutsk State University, API),

L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez
(INAOE, Guillermo Haro Astrophysics Observatory),

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

V. Yurkov, A. Gabovich
(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 230906A ( Fermi GBM team, GCN 34631) errorbox  30270 sec after notice time and 30304 sec after trigger time at 2023-09-06 21:20:11 UT, with upper limit up to  18.4 mag. The observations began at zenith distance = 79 deg. The sun  altitude  is -58.8 deg. 

The galactic latitude b = -34 deg., longitude l = 254 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2266531

We obtain a following upper limits.  

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

   30334 | 2023-09-06 21:20:11 |         MASTER-SAAO | (05h 00m 24.99s , -46d 27m 50.7s) |   C |    60 | 18.0 |        
   30505 | 2023-09-06 21:23:02 |         MASTER-SAAO | (05h 12m 37.40s , -50d 13m 19.5s) |   C |    60 | 18.3 |        
   30755 | 2023-09-06 21:27:12 |         MASTER-SAAO | (05h 11m 27.14s , -48d 21m 19.4s) |   C |    60 | 18.4 |        
   30835 | 2023-09-06 21:28:32 |         MASTER-SAAO | (05h 23m 34.07s , -48d 20m 18.0s) |   C |    60 | 18.1 |        
   30927 | 2023-09-06 21:30:03 |         MASTER-SAAO | (05h 23m 47.74s , -50d 14m 12.7s) |   C |    60 | 18.2 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB230905B
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34635
SUBJECT: GRB 230905B: AstroSat CZTI detection
DATE:    23/09/07 08:06:48 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

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

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 230905B which was also detected by GECAM-C (Xiong et al., GCN Circ. 34630), and INTEGRAL/SPI-ACS.

The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2023-09-05 15:49:37.50 UTC. The measured peak count rate associated with the burst is 186 (+46, -24) counts/s above the background in the combined data of all quadrants, with a total of 1858 (+502, -520) counts. The local mean background count rate was 447 (+2, -3) counts/s. Using cumulative rates, we measure a T90 of 45 (+14, -22) s.

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

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at: 
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230906A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34636
SUBJECT: GRB 230906A: Swift ToO observations
DATE:    23/09/07 14:44:50 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

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

Swift has initiated a ToO observation of the IPN GRB 230906A. 
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021621

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: GRB230906A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34637
SUBJECT: IPN triangulation of GRB 230906A (short)
DATE:    23/09/07 14:58:27 GMT
FROM:    Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>

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

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

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

E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

and

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

The bright, short-duration GRB 230906A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 34631)
was detected by Fermi (GBM trigger 715697712), INTEGRAL (SPI-ACS),
Konus-Wind, and Mars-Odyssey (HEND) at about 46507 s UT (12:55:07).

We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
---------------------------------------------
  RA(2000), deg                 Dec(2000), deg
 ---------------------------------------------
 Center:
   79.757 (05h 19m 02s) -47.887 (-47d 53' 13")
 Corners:
   79.710 (05h 18m 50s) -47.945 (-47d 56' 41")
   79.748 (05h 19m 00s) -47.986 (-47d 59' 08")
   79.803 (05h 19m 13s) -47.829 (-47d 49' 45")
   79.765 (05h 19m 04s) -47.788 (-47d 47' 17")
 ---------------------------------------------
The error box area is 20 sq. arcmin, and its maximum
dimension is 12 arcmin (the minimum one is 2 arcmin).
The Sun distance was 91 deg.

The IPN localization is consistent with, but reduces the area of,
the Fermi-GBM final localization (glg_healpix_all_bn230715190_v00).

Swift ToO has been submitted (GCN 34636).

This localization may be improved.

A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB230906_T46507/IPN/

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


GRB_name: GRB230906A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34638
SUBJECT: Konus-Wind detection of GRB 230906A (short)
DATE:    23/09/07 16:26:29 GMT
FROM:    Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>

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

The short GRB 230906A (Fermi GBM detection:  the Fermi GBM team, GCN Circ 34631;
IPN triangulation: Kozyrev et al., GCN Circ 34637)
triggered Konus-Wind (KW) at T0=46507.186 s UT (12:55:07.186).

The burst light curve shows a multi-peaked structure
which starts at ~T0-0.256 s and has a duration of ~0.29 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/GRB230906_T46507/

As observed by Konus-Wind, the burst had
a total fluence of (2.55 Â± 0.23)x10^-6 erg/cm^2 and
a 16-ms peak energy flux, measured from T0,
of (3.48 Â± 0.34)x10^-5 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 - 15 MeV range by a power law with exponential
cutoff (CPL) model: dN/dE ~ (E^alpha)*exp(-E*(2+alpha)/Ep)
with  alpha = -0.56(-0.13,+0.14) and Ep = 522(-56,+65) keV (chi2 = 27/35 dof).
Fitting this spectrum by a Band function yields the same values of alpha and Ep,
and an upper limit on the high energy photon index beta of -2.1 (chi2 = 27/34 dof).

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


GRB_name: GRB230906A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34639
SUBJECT: GRB 230906A: Swift-XRT observations
DATE:    23/09/07 23:22:03 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

A.P. Beardmore (U. Leicester), B. Sbarufatti (INAF-OAB), A. D'Ai
(INAF-IASFPA), A. Melandri (INAF-OAR), J. D. Gropp (PSU), S. Dichiara
(PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester) and P.A. Evans
(U. Leicester) reports on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the IPN-detected
burst GRB 230906A (Kozyrev et al., GCN Circ 34637), collecting 4.7 ks
of Photon Counting (PC) mode data between T0+93.0 ks and T0+106.0 ks. 

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):  79.7533  =  05:19:0.79
  Dec (J2000): -47.8930  =  -47:53:34.9
  Error: 6.4 arcsec (radius, 90% conf.)
  Count-rate: (1.73 [+0.88, -0.67])e-3 ct s^-1  
  Distance: 23 arcsec from IPN position.

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
https://www.swift.ac.uk/ToO_GRBs/00021621.

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


GRB_name: GRB230205A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34640
SUBJECT: GRB 230205A: LBT spectroscopy of two host galaxy candidates
DATE:    23/09/08 08:40:01 GMT
FROM:    Elisabetta Maiorano at INAF <elisabetta.maiorano@inaf.it>

E. Maiorano (INAF-OAS), V. D'Elia (SSDC & INAF-OAR), D. B. Malesani (Radboud Univ. and DAWN/NBI), A. Rossi, E. Palazzi (INAF-OAS), P. Dâ€™Avanzo (INAF-OAB), A. Melandri ( INAF-OAR), M. De Pasquale (Messina Univ.) on behalf of CIBO collaboration.

We report the results of the spectroscopic observations of two host galaxy candidates for the short GRB 230205A (Ambrosi et al., GCN 33271), first identified by Tomasella et al. (GCN 33302) and Urata et al. (GCN 33307) in deep Subaru archival imaging.

The optical spectra of the two candidate host galaxies were obtained with the Multi-Object Double Spectrographs (MODS) instrument mounted on the 2x8.4-m LBT telescope (Mt. Graham, AZ, USA) on 2023-03-04, 27 days after the burst trigger. The spectra cover the wavelength range 3200-10000 AA, with a total of exposure time of 1.5 hours.

We detect a faint and red continuum with few emission lines for the brightest galaxy that we tentatively identify as H-alpha, and H-beta at a common redshift of z=0.429 (consistent with the photometric redshift of z = 0.484 Â± 0.090 provided by SDSS, see Tomasella et al., GCN 33302). The spectral trace of the fainter galaxy is too weak to allow a reliable identification of any emission line, thus not permitting its redshift estimate.

Multiband photometry was also collected between June and July (4-5 months after the GRB trigger) in the r, z and H bands, with both galaxies detected in all filters. These images also show an additional fainter host galaxy candidate at coordinates 13:28:16.56 +46:43:34.7, underlining the complexity of the field.

We acknowledge the excellent support from the LBTO and LBT-INAF staff, particularly D. Thompson, E. Marini, and D. Paris, in obtaining these observations.


GRB_name: GRB230818A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34641
SUBJECT: GRB 230818A: radio observation with the VLA
DATE:    23/09/08 13:08:24 GMT
FROM:    Stefano Giarratana at University of Bologna <s.giarratana@ira.inaf.it>

S. Giarratana (University of Bologna, INAF-IRA), M. Giroletti
(INAF-IRA), G. Ghirlanda (INAF-OAB), N. Di Lalla (Stanford Univ.),
N. Omodei (Stanford Univ.)

At 23:33:30 UT on 2023 August 23 (T_mid = 5.02 days post-burst) the
Karl G. Jansky VLA observed the field of GRB 230818A (Fermi GBM
team, GCN 34478; Tohuvavohu et al., GCN 34479) at a central
frequency of 6 and 10 GHz.

The standard J1331+3030 was used as bandpass and flux density
calibrator, while J1912+3740 was used as phase calibrator.

From a preliminary analysis, we do not detect the radio counterpart
of GRB 230818A. The r.m.s. noise level of the images is
11 uJy/beam and 13 uJy/beam at 6 and 10 GHz, respectively.
The synthesized beams are 0.44 x 0.89 arcsec (PA: 81 deg) at 6 GHz
and 0.28 x 0.24 arcsec (PA: -70 deg) at 10 GHz.

We would like to thank the staff of the VLA for approving, executing,
and processing the observations.

The National Radio Astronomy Observatory is a facility of the National
Science Foundation operated under cooperative agreement by Associated
Universities, Inc.

These observations were carried out as part of project SF161095,
approved in the framework of the Fermi - NRAO joint program agreement.


GRB_name: GRB230827A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34642
SUBJECT: GRID detection of GRB 230827A
DATE:    23/09/08 13:21:40 GMT
FROM:    GRID Student Team at Tsinghua University <grid@tsinghua.edu.cn>

Chenyu Wang and Zirui Yang report on behalf of the GRID Collaboration:

GRID-03B and GRID-04, onboard the same CubeSat, report the detection of the long-duration GRB 230827A, which was also detected by Fermi/GBM, Swift/BAT-GUANO, GRBAlpha, VZLUSAT-2, Glowbug and INTEGRAL/SPI-ACS (GCN 34575, 34582, 34583, 34588, 34603).

The event was triggered with GRID on 2023-08-27 at 18:17:41 UTC. The GRID light curve shows a three-pulse temporal structure. The measured burst duration (T90) in the 30-2000 keV range is approximately 57.8 Â± 6.1 seconds.

GRID is a student-led project to monitor the transient gamma-ray sky with multiple detectors onboard different nanosatellites in the era of multi-messenger astronomy. For more information about GRID, please refer to the following references: https://doi.org/10.1007/s10686-019-09636-w and https://doi.org/10.1007/s10686-021-09819-4.


GRB_name: GRB230906A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34643
SUBJECT: GRB 230906A: Swift/UVOT Upper Limits
DATE:    23/09/09 10:53:16 GMT
FROM:    Samantha Oates at University of Birmingham <samantha.oates@alumni.ucl.ac.uk>

S. R. Oates (Lancaster U. ) and M. J. Moss (GSFC)
report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 230906A
93 ks after IPN-detection (Kozyrev et al., GCN Circ 34637). No optical
afterglow consistent with the XRT position  (Beardmore et al., GCN
Circulars 34639), 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            93297        106009        4648          >22.8

The magnitudes in the table are not corrected for the Galactic extinction
due to the reddening of E(B-V) = 0.021 in the direction of the burst
(Schlegel et al. 1998).


GRB_name: GRB230905B
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34644
SUBJECT: Glowbug gamma-ray detection GRB 230905B
DATE:    23/09/09 14:06:23 GMT
FROM:    matthew.kerr@gmail.com

M. Kerr, C.C. Cheung, J. E. Grove, R. Woolf (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge (MSFC), and M.S. Briggs (UAH) report:

The Glowbug gamma-ray telescope [1,2], operating on the International Space Station, reports the detection of GRB 230905B, which was also detected by GECAM-C, AstroSat/CZTI, and INTEGRAL/SPI-ACS (GCN 34630, 34635).

Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2023-09-05 15:49:30.096 with a duration of 12.3 s and a total significance of about 34.6 sigma.  The light curve comprises a single primary peak with three distinct sub-peaks, each lasting for and separated by about two seconds.

Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission over this duration results in a photon index dN/dE~E^x of x=1.5 and a cutoff energy ("Epeak") of 189 keV.  The modeled 10-10000 keV fluence is 1.7e-06 erg/cm^2.

The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.

Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC.  It was launched on 2023 March 15 aboard the Department of Defense Space Test Programâ€™s STP-H9 to the ISS.  The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.

[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006

Distribution Statement A: Approved for public release.  Distribution is unlimited.


GRB_name: GRB230908A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34645
SUBJECT: GRB 230908A: AstroSat CZTI detection
DATE:    23/09/09 19:29:37 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

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

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a GRB 230908A which was also detected by CALET (Trigger Num. 1378226327).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed a single burst of emission that peaked at 2023-09-08 16:41:22 UTC. The measured peak count rate associated with the burst is 447 (+173, -19) counts/s above the background in the combined data of three quadrants (out of four), with a total of 1458 (+285, -371) counts. The local mean background count rate was 327 (+5, -9) counts/s. Using cumulative rates, we measure a T90 of 9.5 (+3, -5) s.

The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed a single burst of emission that peaked at 2023-09-08 16:41:23 UTC. The measured peak count rate associated with the burst is 737 (+71, -75) counts/s above the background in the combined data of three quadrants (out of four), with a total of 4509 (+569, -583) counts. The local mean background count rate was 1096 (+7, -7) counts/s. We measure a T90 of 13 (+5, -2) s from the cumulative Veto light curve.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at: 
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230908A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34647
SUBJECT: GRB 230908A: GRBAlpha detection
DATE:    23/09/09 21:15:07 GMT
FROM:    Marianna DafÄÃ­kovÃ¡ at Masaryk University <500025@mail.muni.cz>

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

The long-duration GRB 230908A (AstroSat detection: GCN 34645; CALET detection: trigger no. 1378226327; INTEGRAL/SPI-ACS peak detection at 2023-09-08 ~16:41:20 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023; arXiv:2302.10048).
The detection was confirmed at the peak time 2023-09-08 16:41:21 UTC. The T90 duration measured by GRBAlpha is 8 s and the overall significance during T90 reaches 40 sigma.

The light curve obtained by GRBAlpha is available here: 
https://grbalpha.konkoly.hu/static/share/GRB230908A_GCN.pdf

All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/ 
GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume. 


GRB_name: GRB230910A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34648
SUBJECT: GRB 230910A: Fermi GBM Final Real-time Localization
DATE:    23/09/10 03:11:28 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

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

At 03:00:01 UT on 10 Sep 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230910A (trigger 716007606.740604 / 230910125).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 57.0, Dec = 45.9 (J2000 degrees, equivalent to J2000 03h 47m, 45d 53'), with a statistical uncertainty of 2.9 degrees.

The angle from the Fermi LAT boresight is 68.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230910125/quicklook/glg_skymap_all_bn230910125.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230910125/quicklook/glg_healpix_all_bn230910125.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230910125/quicklook/glg_lc_medres34_bn230910125.gif


GRB_name: GRB230906A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34649
SUBJECT: GRB 230906A: AstroSat CZTI detection
DATE:    23/09/10 05:39:19 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

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

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of the short GRB 230906A which was also detected by Fermi (Fermi GBM team, GCN Circ. 34631), Konus-Wind (Frederiks et al., GCN Circ. 34638) with IPN localization (Kozyrev et al., GCN Circ. 34637).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed a multi-peak structure that peaked at 2023-09-06 12:55:07.82 UTC. The measured peak count rate associated with the burst is 3406 (+1081, -773) counts/s above the background in the combined data of all quadrants, with a total of 163 (+35, -34) counts. The local mean background count rate was 545 (+43, -67) counts/s. Using cumulative rates, we measure a T90 of 0.09 (+0.03, -0.03) s. 

The source was also clearly detected in the CsI anticoincidence (Veto) detectors in the 100-500 keV energy range. The light curve peaks at 2023-09-06 12:55:07.01 UTC. The measured peak count rate associated with the burst is 1048 (+81, -90) counts/s above the background in the combined data of all quadrants, with a total of 823 (+634, -729) counts. The local mean background count rate was 1430 (+7, -8) counts/s. Due to the intrinsic 1 s binning of Veto data, we cannot reliably estimate a T90 from it.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at: 
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230903A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34650
SUBJECT: GRB 230903A: TESS observations of optical emission
DATE:    23/09/10 14:31:37 GMT
FROM:    Rahul Jayaraman at MIT <rjayaram@mit.edu>

R. Jayaraman (MIT), M.M. Fausnaugh (TTU/MIT), R. Vanderspek (MIT), and G.R. Ricker (MIT) report:

The Transiting Exoplanet Survey Satellite (TESS; Ricker et al. JATIS 2015) observed the location of the gamma-ray burst GRB230903A (GCN 34608, Fermi GBM Team et al.; GCN 34610, Dâ€™Ai et al.) at a 200 second cadence continuously from 2.8 days before the trigger to 3.75 days after the trigger. The GRB occurred during TESS observational Sector 69, in the field of view of Camera 2, CCD 3.

We extracted a light curve from the calibrated TESS Full-Frame Images (FFIs) produced by TICA (Fausnaugh et al. RNAAS 2020), using difference imaging and forced photometry at the enhanced location provided by Swift-XRT in GCN 34625 (Beardmore et al.). Our analysis procedure is described in Fausnaugh et al. 2023 (arXiv:2307.11815).

TESS observations show a flux excess of 5.1-sigma above the background in the 200s FFI exposure that encompasses the Fermi trigger time, corresponding to an apparent magnitude of 17.20 Â± 0.05 in the TESS band (600 nmâ€“1000 nm). Further analysis is ongoing.

The TICA data are publicly available on the MAST archive at https://archive.stsci.edu/hlsp/tica.


GRB_name: GRB230906A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34651
SUBJECT: GRB 230906A: BlackGEM upper limits
DATE:    23/09/10 15:28:47 GMT
FROM:    Simon de Wet at University of Cape Town <simdewet@gmail.com>

S. de Wet (UCT), D. Pieterse (Radboud), P.J. Groot (Radboud/UCT/SAAO) and P.M. Vreeswijk (Radboud) report on behalf of the BlackGEM consortium:

Following the IPN localisation of the short GRB 230906A (Fermi GBM team, GCN 34631) by the Interplanetary Network (Kozyrev et al., GCN 34637), the BlackGEM Unit Telescope 3 (BG3-Opal) located at ESO La Silla, Chile, obtained 2 x 300 s exposures in the q-band (440-720 nm) of the IPN triangulation region. The first observation started at 08:00:42 UT on 2023 September 7, 19.1 hours after the Fermi GBM trigger.

We detect no new transients within the IPN triangulation error region nor at the position of the Swift XRT source (Beardmore et al., GCN 34639) down to a 5-sigma limiting AB magnitude of q=21.53, consistent with the upper limits reported by Swift/UVOT (Oates and Moss, GCN 34643). The depth of our images was negatively affected by ~3 arcsecond seeing.  

BlackGEM is an array of wide-field telescopes designed, built and operated by a consortium consisting of Radboud University, the Netherlands Research School for Astronomy NOVA, KU Leuven, the University of Manchester, Tel Aviv University, the Weizmann Institute, the Hebrew University of Jerusalem, the University of Potsdam, Texas Tech University, the University of California at Davis, the Danish Technical University and the Armagh Observatory and Planetarium.


GRB_name: GRB230911A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34652
SUBJECT: GRB 230911A: Fermi GBM Final Real-time Localization
DATE:    23/09/11 03:20:04 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

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

At 03:09:32 UT on 11 Sep 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230911A (trigger 716094577.87568 / 230911132).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 59.8, Dec = -34.4 (J2000 degrees, equivalent to J2000 03h 59m, -34d 23'), with a statistical uncertainty of 4.1 degrees.

The angle from the Fermi LAT boresight is 50.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230911132/quicklook/glg_skymap_all_bn230911132.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230911132/quicklook/glg_healpix_all_bn230911132.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230911132/quicklook/glg_lc_medres34_bn230911132.gif


GRB_name: GRB230911B
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34653
SUBJECT: GRB 230911B: Fermi GBM Final Real-time Localization
DATE:    23/09/11 04:37:15 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 04:25:49 UT on 11 Sep 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230911B (trigger 716099154.520658 / 230911185).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 351.7, Dec = -55.0 (J2000 degrees, equivalent to J2000 23h 26m, -55d 00'), with a statistical uncertainty of 1.1 degrees.

The angle from the Fermi LAT boresight is 131.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230911185/quicklook/glg_skymap_all_bn230911185.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230911185/quicklook/glg_healpix_all_bn230911185.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230911185/quicklook/glg_lc_medres34_bn230911185.gif


GRB_name: GRB230911B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34654
SUBJECT: Fermi GRB 230911B: Global MASTER-Net observations report
DATE:    23/09/11 05:45:51 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik,  D. Vlasenko,
G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij
(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. Gress, N.M. Budnev, O.Ershova
(Irkutsk State University, API),

L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez
(INAOE, Guillermo Haro Astrophysics Observatory),

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

V. Yurkov, A. Gabovich
(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 230911B ( Fermi GBM team, GCN 34653) errorbox  928 sec after notice time and 961 sec after trigger time at 2023-09-11 04:41:51 UT, with upper limit up to  13.2 mag. The observations began at zenith distance = 24 deg. The sun  altitude  is -63.7 deg. 

The galactic latitude b = -59 deg., longitude l = 326 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2268866

We obtain a following upper limits.  

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

    1052 | 2023-09-11 04:41:51 |         MASTER-OAFA | (23h 25m 02.98s , -55d 03m 29.7s) |   C |   180 | 12.1 |        
    1579 | 2023-09-11 04:50:38 |         MASTER-OAFA | (23h 24m 58.92s , -55d 02m 04.7s) |   C |   180 | 13.2 |        
    2059 | 2023-09-11 04:58:39 |         MASTER-OAFA | (23h 25m 30.11s , -55d 04m 12.8s) |   C |   180 | 13.1 |        
    2630 | 2023-09-11 05:08:09 |         MASTER-OAFA | (23h 25m 03.23s , -55d 03m 59.3s) |   C |   180 | 12.4 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB230911C
Detection_method: Swift Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34655
SUBJECT: GRB 230911C: Swift detection of a burst
DATE:    23/09/11 09:11:10 GMT
FROM:    K.L. Page at U Leicester <klp5@leicester.ac.uk>


E. Sonbas (Adiyaman Univ.), R. Brivio (INAF-OAB), S. Dichiara (PSU),
M. Ferro (INAF-OAB), J.D. Gropp (PSU), A. Y. Lien (U Tampa),
A. Melandri (INAF-OAR), K. L. Page (U Leicester), D. M. Palmer (LANL),
T. Sakamoto (AGU), C. Salvaggio (INAF-OAB) and T. Sbarrato (INAF-OAB)
report on behalf of the Neil Gehrels Swift Observatory Team:

At 08:47:25 UT, the Swift Burst Alert Telescope (BAT) triggered and
located GRB 230911C (trigger=1191188).  Swift slewed immediately to the burst. 
The BAT on-board calculated location is 
RA, Dec 226.782, -41.334 which is 
   RA(J2000) = 15h 07m 08s
   Dec(J2000) = -41d 20' 01"
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 10 sec.  The peak count rate
was ~700 counts/sec (15-350 keV), at ~3 sec after the trigger. 

The XRT began observing the field at 08:49:24.4 UT, 119.0 seconds after
the BAT trigger. Using promptly downlinked data we find an uncatalogued
X-ray source located at RA, Dec 226.79804, -41.32973 which is
equivalent to:
   RA(J2000)  = 15h 07m 11.53s
   Dec(J2000) = -41d 19' 47.0"
with an uncertainty of 4.2 arcseconds (radius, 90% containment). This
location is 46 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 (9.36 x
10^20 cm^-2, Willingale et al. 2013), with an excess column of 4
(+3.90/-3.22) x 10^21 cm^-2 (90% confidence). 

Processed UVOT data were not available at low latency, with the images
affected by the attitude issues reported in GCN Circ. 34633. 

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


GRB_name: GRB230911D
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34656
SUBJECT: GRB 230911D: Fermi GBM Final Localization
DATE:    23/09/11 09:35:37 GMT
FROM:    rachel.hamburg@ijclab.in2p3.fr

The Fermi GBM team reports the detection of a likely long GRB.
 
At 07:53:09.73 UT on 11 September 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230911D (trigger 716111594 / 230911329).
 
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 154.9, Dec = -20.9 (J2000 degrees, equivalent to J2000 +10h 19m, -20d 55'), with a statistical uncertainty of 1.0 degree.
 
The angle from the Fermi LAT boresight is 67 degrees.
 
The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230911329/quicklook/glg_skymap_all_bn230911329.png

The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230911329/quicklook/glg_healpix_all_bn230911329.fit

The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230911329/quicklook/glg_lc_medres34_bn230911329.gif


GRB_name: GRB230911D
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34657
SUBJECT: GRB 230911D: BALROG localization (Fermi Trigger  716111594/ GRB 230911329)
DATE:    23/09/11 10:08:57 GMT
FROM:    Jochen Greiner at MPE <jcgrog@mpe.mpg.de>

B. Biltzinger, T. Preis, J. Burgess & J. Greiner (all MPE Garching) report:

The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
 at 07:53:09 on 11 Sept. 2023 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) = 148.9+/-0.2 deg
Decl.(2000.0) = -23.4+/-0.7 deg
We estimate an additional systematic error of 1 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB230911329/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB230911329/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB230911329/json

                        


GRB_name: GRB230811D
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34659
SUBJECT: Konus-Wind detection of GRB 230811D
DATE:    23/09/11 15:58:18 GMT
FROM:    Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>

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

The long GRB 230911D (Fermi GBM team, GCN 34656)
triggered Konus-Wind (KW) at T0=28387.687 s UT (07:53:07.687).

The burst light curve shows a bright, multi-peaked emission complex,
which starts at ~T0-3 s, peaks at ~T0+15 s,
and has a total duration of ~60 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/GRB230911_T28387/

As observed by Konus-Wind, the burst had
a fluence of (1.57 Â± 0.12)x10^-4 erg/cm^2 and
a 64-ms peak energy flux, measured from T0 + 14.848 s,
of (1.42 Â± 0.15)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+54.272 s)
is best fit in the 20 keV - 15 MeV range
by a GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.74 (-0.06,+0.06),
the high energy photon index beta = -2.44 (-0.28,+0.17),
the peak energy Ep = 343 (-22,+23) keV,
chi2 = 126/96 dof.

The spectrum near the peak count rate (measured from T0+14.336 to T0+16.384 s)
is best fit in the 20 keV - 15 MeV range
by a GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -0.13 (-0.16,+0.18),
the high energy photon index beta = -2.56 (-0.32,+0.21),
the peak energy Ep = 405 (-43,+48) keV,
chi2 = 95/73 dof.

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


GRB_name: GRB230911B
Detection_method: correction
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34660
SUBJECT: GRB 230911B: correction to the KW GCN 34659
DATE:    23/09/11 16:08:48 GMT
FROM:    Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>

D. Frederiks, on behalf of the KW team,

the subject line of GCN 34659 contains a typo in the GRB name
and should read as "Konus-Wind detection of GRB 230911D"

We are sorry for the inconvenience.


GRB_name: GRB230908A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34661
SUBJECT: GRB 230908A: Swift/BAT-GUANO detection of a long burst outside the coded FOV 
DATE:    23/09/11 16:08:54 GMT
FROM:    GAYATHRI RAMAN at PSU <gzr5209@psu.edu>

Aaron Tohuvavohu (U Toronto), Gayathri Raman (PSU),  Jamie A. Kennea (PSU), James DeLaunay (U Alabama),  Samuele Ronchini (PSU), Tyler Parsotan (NASA GSFC) report: 

Swift/BAT did not localize GRB 230908A onboard (T0: 2023-09-08T16:41:17.84 UTC, CALET detection: trigger no. 1378226327, AstroSat detection: GCN 34645, GRBAlpha detection: GCN 34647) 

The CALET notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). 

Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 90 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. 

The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 76.33 in a 8.192 s analysis time bin, starting at T0 + 2.0482 s. 

NITRATES results are consistent with a burst coming from outside the FOV, with DeltaLLHOut of -134.81.

See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut. 

GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. 

A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/


GRB_name: GRB230911C
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34662
SUBJECT: GRB 230911C: GOTO optical upper limits
DATE:    23/09/11 16:16:25 GMT
FROM:    Amit Kumar at University of Warwick, UK <amitkundu515@gmail.com>

D. Oâ€™Neill; A. Kumar; B. P. Gompertz; K. Ulaczyk; G. Ramsay; R. Starling; K. Ackley; M. J. Dyer; J. Lyman; F. Jiminez-Ibarra; D. Steeghs; D. K. Galloway; V. Dhillon; P. O'Brien; K. Noysena; R. Kotak; R. P. Breton; L. K. Nuttall; E. Pall'e and D. Pollacco report on behalf of the GOTO collaboration:

We report on observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022) in response to GRB 230911C (Sonbas et al., GCN 34655). Three targeted observations were performed by GOTO-South, located at Siding Spring Observatory, between 08:52:42 UT and 09:14:52 UT on 2023-09-11 (5.28, 16.08 and 27.47 minutes after trigger). Each observation consisted of 4x90s exposures in the GOTO L-band (400-700 nm). Images were processed immediately after acquisition using the GOTO pipeline. We identify no candidate optical counterparts within the enhanced XRT localisation region (Evans et al., GCN 34658). The 5-sigma limiting magnitudes were 20.7, 20.4 and 21.0 mag, respectively.

GOTO (https://goto-observatory.org) is a network of telescopes operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC). We note that this is the first scientific contribution from GOTO-South.


GRB_name: GRB230911B
Detection_method: INTEGRAL
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34664
SUBJECT: GRB 230911B: GRBAlpha and VZLUSAT-2 joint detection
DATE:    23/09/11 20:36:40 GMT
FROM:    Marianna DafÄÃ­kovÃ¡ at Masaryk University <500025@mail.muni.cz>

M. Dafcikova, J. Ripa (Masaryk U.), A. Pal (Konkoly Observatory),  N. Werner  (Masaryk U.), M. Ohno, H. Takahashi (Hiroshima U.), L. Meszaros, B. Csak (Konkoly Observatory), N. Husarikova, F. Munz, M. Topinka, M. Kolar, J.-P. Breuer, F. Hroch (Masaryk U.), J. Hudec, J. Kapus, M. Frajt, M. Rezenov (Spacemanic s.r.o), R. Laszlo, M. Koleda (Needronix s.r.o), G. Galgoczi (Wigner Research Center/Eotvos U.), N. Uchida (ISAS/JAXA), T. Enoto (Kyoto U.), Zs. Frei (Eotvos U.), Y. Fukazawa, K. Hirose, H. Poon, H. Matake (Hiroshima U.), S. Hisadomi (Nagoya U.), Y. Ichinohe (Rikkyo U.), L. L. Kiss (Konkoly Observatory),  T. Mizuno (Hiroshima U.), K. Nakazawa (Nagoya U.), H. Odaka (U. Tokyo), K. Torigoe, Y. Uchida (Hiroshima U.), P. Svoboda, V. Daniel, J. Dudas, M. Junas, J. Gromes (VZLU), I. Vertat (FEL ZCU), T. Urbanec, M. Kasal, A. Povalac (Brno U. of Technology), M. Smelko, P. Hanak, P. Lipovsky (Technical U. of Kosice), T. Bozoki, G. Dalya, G. Friss, K. Kapas, J. Takatsy (Eotvos U.), N. Kogiso, M. Yoneyama (Osaka Metropolitan U.), M. Moritaki (U. Tokyo), T. Kano (U. Michigan) -- the GRBAlpha and VZLUSAT-2/GRB payload collaborations

We report a joint detection of a long-duration GRB 230911B by the GRBAlpha 1U CubeSat (Pal et al. 2023; arXiv:2302.10048) and the GRB detector on board of VZLUSAT-2 3U CubeSat (https://www.vzlusat2.cz/en/). The event was also observed by Fermi/GBM (GCN 34653) and INTEGRAL/SPI-ACS at ~2023-09-11 04:25:51 UT.

The GRBAlpha detection was confirmed at the peak time 2023-09-11 04:25:51 UTC. The T90 duration is 15 s and the significance during T90 reaches 13 sigma.

The light curve obtained by GRBAlpha is available here:
https://grbalpha.konkoly.hu/static/share/GRB230911B_GCN.pdf

The VZLUSAT-2 detection was confirmed at the peak time 2023-09-11 04:25:50 UTC. The data acquisition was performed by the GRB detector unit no. 1. The T90 duration is 15 s and the significance during T90 reaches 9 sigma.

The light curves obtained by VZLUSAT-2 are available here:
https://vzlusat2.konkoly.hu/static/share/GRB230911B_GCN_VZLUSAT2.pdf

All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/ 
GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume. 

All VZLUSAT-2 detections are listed at: https://monoceros.physics.muni.cz/hea/VZLUSAT-2/
The GRB detectors on VZLUSAT-2 are a demonstration payload for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). Two GRB modules of VZLUSAT-2 are placed in a perpendicular manner and each consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~30 keV to ~1000 keV. VZLUSAT-2 was launched on 2022 January 13 from Cape Canaveral.


GRB_name: GRB230911C
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34665
SUBJECT: GRB 230911C: Swift/UVOT Upper Limits
DATE:    23/09/11 20:49:01 GMT
FROM:    Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and E. Sonbas (Adiyaman Univ.) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 230911C 122 s after the BAT trigger (Sonbas et al., GCN Circ. 34655).
No optical afterglow consistent with the XRT position (Evans et al., GCN Circ. 34658) 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           122          272          147         >20.4
white              122         4926          289         >21.0
u_FC               280          530          246         >19.7
u                  280         4572          708         >20.2
b                  537         4778          235         >19.8
w1                 661         4368          216         >19.0
w2                 587          781           39         >18.2

The magnitudes in the table are not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.101 in the direction of the burst (Schlegel et al. 1998).


GRB_name: GRB230911C
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34667
SUBJECT: GRB230911C: LCOGT Optical Upper Limits
DATE:    23/09/11 20:58:29 GMT
FROM:    Robert Strausbaugh at Eastern Illinois University <rstrausbaugh@eiu.edu>

R. Strausbaugh (Eastern Illinois University), A. Cucchiara (NASA) report on behalf of a larger collaboration:

We observed the Swift GRB 230911C (Sonbas et al., GCN 34655) field with the LCOGT 1-meter Sinistro instrument at the South African Astronomical Observatory site, on September 11, from 17:20 to 17:52 UT (corresponding to 8.55 to 9.08 hours from the GRB trigger time) with the SDSS r and i filters.

We performed a series of 3x300s exposures in each band.  We do not detect a source within the Swift-XRT enhanced error region (Evans et al., GCN 34658) in either band.

The following upper limits are calculated using the USNO-B1.0 catalog as reference:

r > 21.6
i > 21.1

These magnitudes are not corrected for galactic extinction.


GRB_name: GRB230911D
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34668
SUBJECT: GRB 230911D: Fermi-LAT detection
DATE:    23/09/11 22:12:40 GMT
FROM:    N. Di Lalla at Stanford University <niccolo.dilalla@stanford.edu>

F. Longo (University and INFN, Trieste), D. Kocevski (NASA/MSFC), N. Omodei (Stanford University), N. Di Lalla (Stanford University) report on behalf of the Fermi-LAT Collaboration:

On September 11, 2023 Fermi-LAT detected high-energy emission from GRB 230911D, which was also detected by Fermi-GBM (trigger 716111594 / 230911329, GCN 34656) and Konus-Wind (GCN 34659).

The best LAT on-ground location is found to be

RA, Dec = 151.9, -26.0 (degrees, J2000)

with an error radius of 0.3 deg (90% containment, statistical error only). This was 73 deg from the LAT boresight at the time of the GBM trigger:

T0 = 07:53:09.73 UT.

The data from the Fermi-LAT show a significant increase in the event rate after the GBM trigger that is spatially correlated with the GBM emission with high significance. The photon flux above 100 MeV in the time interval 0-1000 s after the GBM trigger is (2.3 +/- 0.8)E-5 ph/cm2/s.

The estimated photon index above 100 MeV is -1.9 +/- 0.2. The highest-energy photon is a 4.6 GeV event which is observed 154 seconds after the GBM trigger.

A Swift ToO has been requested for this burst.

The Fermi-LAT point of contact for this burst is Makoto Arimoto (arimoto@se.kanazawa-u.ac.jp <mailto:arimoto@se.kanazawa-u.ac.jp>)

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: GRB230911D
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34669
SUBJECT: IPN triangulation of GRB 230911D (long)
DATE:    23/09/11 22:32:48 GMT
FROM:    Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>

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

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

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

E. Bozzo and C. Ferrigno, on behalf of the INTEGRAL SPI-ACS GRB team,

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

and

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

The bright, short-duration GRB 230911D
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 34656;
BALROG localization: Biltzinger et al., GCN Circ. 34657;
Konus-Wind detection: Frederiks et al., GCN Circ. 34659;
Fermi-LAT detection: Longo et al., GCN Circ. 34668)
was detected by Fermi (GBM trigger 716111594), INTEGRAL (SPI-ACS),
Konus-Wind, Swift (BAT), and Mars-Odyssey (HEND)
at about 28389 s UT (07:53:09).
The burst was outside the coded field of view of the BAT.

We have triangulated it to a preliminary, 3 sigma error box
whose coordinates are:
 ---------------------------------------------
  RA(2000), deg                 Dec(2000), deg
 ---------------------------------------------
 Center:
  151.360 (10h 05m 26s) -25.633 (-25d 38' 00")
 Corners:
  151.696 (10h 06m 47s) -26.192 (-26d 11' 31")
  151.638 (10h 06m 33s) -26.200 (-26d 12' 01")
  151.036 (10h 04m 09s) -25.072 (-25d 04' 18")
  151.093 (10h 04m 22s) -25.064 (-25d 03' 51")
 ---------------------------------------------
The error box area is 226 sq. arcmin, and its maximum
dimension is 1.3 deg (the minimum one is 3 arcmin).
The Sun distance was 35 deg.

The IPN localization is consistent with, but reduces the area of,
the Fermi-LAT localization (GCN 34668).

This localization may be improved.

A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB230911_T28387/IPN


GRB_name: GRB230911D
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34670
SUBJECT: GRB 230911D: Fermi GBM observation
DATE:    23/09/11 22:45:14 GMT
FROM:    Lorenzo Scotton at UAH <lscottongcn@outlook.com>

L. Scotton (UAH), R. Hamburg (CNRS/IJCLab), and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 07:53:09.72 UT on 11 September 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 230911D (trigger 716111594 / 230911329),
which was also detected by the Fermi LAT (F. Longo et al. 2023, GCN 34668) 
and Konus-Wind (D. Frederiks et al. 2023, GCN 34659).

The Fermi GBM Final Localization (GCN 34656) is consistent with the Fermi LAT position.

The angle from the Fermi LAT boresight at the GBM trigger time is 72 degrees.

The GBM light curve consists of multiple peaks
with a duration (T90) of about 45.6 s (50-300 keV).
The time-averaged spectrum from T0-4.4 s to T0+77.6 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.00 +/- 0.01 and
the cutoff energy, parameterized as Epeak, is 429.9 +/- 7.8 keV

The event fluence (10-1000 keV) in this time interval is 
(1.214 +/- 0.007)E-04 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+16.1 s in the 10-1000 keV band
is 24.8 +/- 0.3 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak= 420.6 +/- 9.0 keV, alpha = -1.00 +/- 0.01 and beta = -3.02 +/- 0.25.

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: GRB230911C
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34671
SUBJECT: Swift GRB 230911C: Global MASTER-Net observations report
DATE:    23/09/11 23:34:53 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik,  D. Vlasenko,
G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij
(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. Gress, N.M. Budnev, O.Ershova
(Irkutsk State University, API),

L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez
(INAOE, Guillermo Haro Astrophysics Observatory),

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

V. Yurkov, A. Gabovich
(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 230911C ( E. Sonbas et al., GCN 34655) errorbox  51970 sec after notice time and 52039 sec after trigger time at 2023-09-11 23:14:45 UT, with upper limit up to  17.3 mag. Observations started at twilight.  The observations began at zenith distance = 37 deg. The sun  altitude  is -11.6 deg. 

The galactic latitude b = 14 deg., longitude l = 329 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2268945

We obtain a following upper limits.  

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

   52130 |         MASTER-OAFA |   C |   180 | 16.3 |        
   52362 |         MASTER-OAFA |   C |   180 | 16.5 |        
   52795 |         MASTER-OAFA |   C |   180 | 17.3 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB230906A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34672
SUBJECT: GRB 230906A: Chandra detection of the X-ray afterglow
DATE:    23/09/11 23:51:20 GMT
FROM:    Brendan O'Connor at CMU <oconnorb@umd.edu>

B. O'Connor (CMU), S. Dichiara (PSU), E. Troja (UTV), report on behalf of a larger collaboration:

We carried out a Chandra Target of Opportunity (ToO) observation of the IPN localized short GRB 230906A (Fermi GBM team, GCN 34631; Kozyrev et al., GCN 34637) under program 24500202 (PI: S. Dichiara). We used the ACIS-S camera with a total exposure of 19.8 ks beginning on 2023-09-11 04:58:29 UT, corresponding to ~4.7 days after the initial trigger. 

At the location of the Swift XRT candidate afterglow (Beardmore et al., GCN 34639) uncovered during tiled observations of the IPN localization (Evans et al., GCN 34636), we detect a clear X-ray source at the North-East edge of the XRT localization. The source is located at 

RA, DEC = 05:19:01.52, -47:53:32.66 

with an uncertainty of 0.8" (systematic + statistical). The source shows signs of fading compared to previous XRT observations. We note that there is no obvious host galaxy at this location in the Legacy Survey, although multiple sources exist within a few arcseconds. 

We would like to thank Patrick Slane, Harvey Tananbaum, Dan Schwartz, Jack Steiner, Brad Wargelin, and the entire CXO staff for rapidly approving and planning this observation. 


GRB_name: GRB230911C
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34673
SUBJECT: GRB230911C: BOOTES-6/DPRT optical upper limit 
DATE:    23/09/12 01:31:57 GMT
FROM:    Youdong HU at IAA-CSIC <huyoudong072@hotmail.com>

E. Fernandez-Garcia, Y.-D. Hu, I. Perez-Garcia, M.D. Caballero-Garcia, R. Sanchez-Ramirez, S. Guziy, S.-Y. Wu and A. J. Castro-Tirado (IAA-CSIC, Granada), P. J. Meintjes and H. J. van Heerden (UFS, South Africa), A. Martin-Carrillo and L. Hanlon (UCD, Ireland) and C. J. Perez del Pulgar (UMA, Malaga), on behalf of a larger collaboration, report:

Following the detection of GRB 230911C by Swift (Sonbas et al. GCNC 34655), the BOOTES-6/DPRT 0.6m robotic telescope at Boyden Observatory in Maselspoort (South Africa) automatically observed the GRB location starting on Sep. 11, 17:26 UT (~ 8.7 h after trigger). No new optical source is detected on the co-added images (3 x 60 s, i-filter & 3 x 60 s, Z-filter) within the enhanced Swift/XRT error region (Evans et al. GCNC 34658) down to 19.2 mag and 18.5 mag respectively, which are consistent with reports from GOTO (O'Neill et al. GCNC 34662), UVOT (Breeveld et al. GCNC 34665), LCOGT (Strausbaugh et al. GCNC 34667) and MASTER (Lipunov et al. GCNC 34671).

We thank the staff at Boyden Observatory for their excellent support.


GRB_name: GRB230911C
Detection_method: Swift-BAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34675
SUBJECT: GRB 230911C: Swift-BAT refined analysis
DATE:    23/09/12 03:07:59 GMT
FROM:    Amy <yarleen@gmail.com>

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

Using the data set from T-61 to T+243 sec from the recent telemetry
downlink, we report further analysis of BAT GRB 230911C (trigger #1191188)
(Sonbas et al., GCN Circ. 34655).  The BAT ground-calculated position is
RA, Dec = 226.796, -41.356 deg which is
   RA(J2000)  =  15h 07m 11.0s
   Dec(J2000) = -41d 21' 21.2"
with an uncertainty of 2.0 arcmin, (radius, sys+stat, 90% containment).
The partial coding was 95%.

The mask-weighted light curve shows multiple weak overlapping pulses that
start at ~T-9 s and end at ~T+10 s. T90 (15-350 keV) is 16.21 +- 2.89 sec
(estimated error including systematics).

The time-averaged spectrum from T-8.63 to T+9.58 sec is best fit by a simple
power-law model.  The power law index of the time-averaged spectrum is
1.26 +- 0.28.  The fluence in the 15-150 keV band is 3.8 +- 0.6 x 10^-7
erg/cm2.
The 1-sec peak photon flux measured from T+2.07 sec in the 15-150 keV band
is 0.7 +- 0.2 ph/cm2/sec.  All the quoted errors are at the 90% confidence
level.

The results of the batgrbproduct analysis are available at
http://gcn.gsfc.nasa.gov/notices_s/1191188/BA/


GRB_name: GRB230911C
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34676
SUBJECT: GRB 230911C: Swift-XRT refined Analysis
DATE:    23/09/12 11:45:52 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

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

We have analysed 7.2 ks of XRT data for GRB 230911C, from 103 s to 74.1
ks after the  BAT trigger. The data comprise 106 s in Windowed Timing
(WT) mode (the first 9 s were taken while Swift was slewing) with the
remainder in Photon Counting (PC) mode. 

The late-time light curve (from T0+4.2 ks) can be modelled with a
power-law decay with a decay index of alpha=0.48 (+0.22, -0.18).

A spectrum formed from the PC mode data can be fitted with an absorbed
power-law with a photon spectral index of 1.86 (+0.26, -0.21). The
best-fitting absorption column is  1.3 (+0.9, -0.3) x 10^21 cm^-2,
consistent with the Galactic value of 9.4 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 3.6 x 10^-11 (4.4 x
10^-11) erg cm^-2 count^-1. 

A summary of the PC-mode spectrum is thus:
Total column:      1.3 (+0.9, -0.3) x 10^21 cm^-2
Galactic foreground: 9.4 x 10^20 cm^-2
Excess significance: <1.6 sigma
Photon index:      1.86 (+0.26, -0.21)

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/01191188.

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


GRB_name: GRB230911B
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34677
SUBJECT: GRB 230911B: AstroSat CZTI detection
DATE:    23/09/12 13:29:01 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

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

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of the long-duration GRB 230911B which was also detected by Fermi-GBM (Fermi GBM team, GCN Circ. 34653) along with GRBAlpha and VZLUSAT-2 (Dafcikova et al., GCN Circ. 34664).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2023-09-11 04:25:51.50 UTC. The measured peak count rate associated with the burst is 467 (+56, -35) counts/s above the background in the combined data of all quadrants, with a total of 3390 (+378, -416) counts. The local mean background count rate was 593 (+4, -4) counts/s. Using cumulative rates, we measure a T90 of 15 (+5, -3) s.

The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2023-09-11 04:25:51.83 UTC. The measured peak count rate associated with the burst is 790 (+75, -76) counts/s above the background in the combined data of all quadrants, with a total of 4781 (+532, -605) counts. The local mean background count rate was 1400 (+6, -7) counts/s. We measure a T90 of 14 (+7, -3) s from the cumulative Veto light curve.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230911D
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34678
SUBJECT: GRB 230911D: NuSTAR Detection of Prompt Emission
DATE:    23/09/12 17:57:47 GMT
FROM:    Brian Grefenstette at Caltech/NuSTAR <bwgref@srl.caltech.edu>

B. Grefenstette and A. Jaodand (Caltech) report on behalf of the NuSTAR Search for INteresting Gamma-ray Signals (SINGS) working group:

The NuSTAR SINGS working group reports the detection of prompt emission from the Long GRB 230911D in both the NuSTAR CsI anti-coincidence shields and in the CdZnTe hard X-ray imagers. This GRB was identified through a blind search using the CsI shield rates. Details of the search algorithm will be described in a future paper.

The NuSTAR GRB search algorithm triggered at 2023-09-11T07:53:11, which is roughly 1.25-s after the Fermi detection (Hamburg et al., GCN Circ. 34656). When we consider the 1-s resolution of the shield data combined with the smoothing of the search algorithm, we consider the NuSTAR GRB time to be consistent with the time reported by Fermi.

Using the GRB localization (Greiner, et al., GCN Circ. 34657) and the NuSTAR trigger time, we estimate that the GRB was above the Earth's horizon as seen by NuSTAR and roughly 83-degrees off-axis from the NuSTAR boresight at the time of the GRB (e.g., through the side of the instrument).

The CsI data are recorded at 1 Hz and show a broad burst with multiple peaks. 1-sec count rates peaked at ~4,000 counts per second in both the FPMA and FPMB shield units. Typical background rates are ~1,000 counts per second.

The burst was also coincidentally detected in both CdZnTe detectors, with peak count rates of ~30 counts above 100 keV in 5-s time bins.

Flux calibration from the CdZnTe detectors for far off-axis is currently not possible since the X-rays observed by the CdZnTe detectors this far off-axis likely have multiple scatters in the instrument before being recorded by the X-ray detectors. Work on understanding the response and converting measured rates to incident fluxes is on-going.

The automated light curve report for this GRB can be found here:

https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/reports/2023/230911D/

Information on NuSTAR SINGS can be found here: 

https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/

NuSTAR is a NASA Small Explorer mission led by Caltech and managed by JPL for NASAâ€™s Science Mission Directorate in Washington. 


GRB_name: GRB230908A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34679
SUBJECT: GRB 230908A: CALET Gamma-Ray Burst Monitor detection
DATE:    23/09/13 04:14:01 GMT
FROM:    Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>

N. Cannady (GSFC/UMBC), A. Yoshida, T. Sakamoto, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA),
Y. Asaoka (ICRR), S. Torii, Y. Akaike, K. Kobayashi (Waseda U),
Y. Shimizu, T. Tamura (Kanagawa U),
M. L. Cherry (LSU), S. Ricciarini (U of Florence),
P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The long GRB 230908A (AstroSat CZTI detection: Navaneeth et al.,
GCN Circ. 34645; GRBAlpha detection: Dafcikova et al., GCN
Circ. 34647; Swift/BAT-GUANO detection: Tohuvavohu et al.,
GCN Circ. 34661) triggered the CALET Gamma-ray Burst Monitor 
(CGBM) at 16:41:17.84 UTC on 8 September 2023
(http://cgbm.calet.jp/cgbm_trigger/flight/1378226327/index.html).
The burst signal was seen by all CGBM detectors.

The burst light curve shows a single pulse that starts
at T+2.1 sec, peaks at T+4.1 sec, and ends at T+9.6 sec.
The T90 and T50 durations measured by the SGM data are 6.2 +/- 0.6 sec
and 2.7 +/- 0.2 sec (40-1000 keV), respectively.

The ground-processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1378226327/

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


GRB_name: GRB230913A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34680
SUBJECT: GRB 230913A: Fermi GBM Final Real-time Localization
DATE:    23/09/13 08:06:34 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 07:56:12 UT on 13 Sep 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230913A (trigger 716284577.16364 / 230913331).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 287.6, Dec = 78.9 (J2000 degrees, equivalent to J2000 19h 10m, 78d 54'), with a statistical uncertainty of 6.5 degrees.

The angle from the Fermi LAT boresight is 41.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230913331/quicklook/glg_skymap_all_bn230913331.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230913331/quicklook/glg_healpix_all_bn230913331.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230913331/quicklook/glg_lc_medres34_bn230913331.gif


GRB_name: GRB230911A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34681
SUBJECT: GRB 230911A: GOTO optical counterpart candidate
DATE:    23/09/13 10:07:56 GMT
FROM:    Sergey Belkin at Monash University <sergey.belkin@monash.edu>

S. Belkin; B. P. Gompertz; A. Kumar; K. Ackley; K. Wiersema; D. Oâ€™Neill; T. Killestein; R. Starling; M. J. Dyer; J. Lyman; K. Ulaczyk; F. Jimenez-Ibarra; D. Steeghs; D. K. Galloway; V. Dhillon; P. O'Brien; G. Ramsay; K. Noysena; R. Kotak; R. P. Breton; L. K. Nuttall; E. Pall'e and D. Pollacco report on behalf of the GOTO collaboration:

We report on observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022) in response to GRB 230911A (Fermi GBM team, GCN 34652). Observations were performed by GOTO North and South between 04:19:47 UT on 2023-09-11 and 17:08:39 UT on 2023-09-12 (1.17 to 37.98 hours after trigger). Each observation consisted of 4x90s exposures in the GOTO L-band (400-700 nm).

Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using recent survey observations of the same pointings. Source candidates were initially filtered using a classifier (Killestein et al. 2021) and cross-matched against a variety of contextual and minor planet catalogues. Human vetting was carried out in real time on any candidates that passed the above checks.

We identify one candidate optical counterpart consistent within the GBM 90% localisation region. We find no evidence of this source prior to the GRB trigger time in previous GOTO observations, the ZTF observations provided by the Lasair broker (Smith et al. 2019), or the ATLAS forced photometry server (Shingles et al. 2021). However, we caution that the last available observation of the field was taken by ATLAS nine days before the GRB trigger.

Name | RA(J2000) | Dec(J2000) | Filter | Mag(AB) | t - trig(hrs)

GOTO23akf | 03:50:00.51 | -29:49:30.66 | L | 19.22 +/- 0.10 | 1.17 

This source is seen to decay as a power-law with an index of 0.61 +/- 0.07 across 7 epochs of observations. No object is present at this position in the Legacy Survey (Dey et al. 2019).

Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction.

GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC).


GRB_name: GRB230913A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34682
SUBJECT: Fermi GRB 230913A: Global MASTER-Net observations report
DATE:    23/09/13 11:30:45 GMT
FROM:    Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>

V. Lipunov, V.Kornilov, E. Gorbovskoy, K. Zhirkov, N.Tyurina, P.Balanutsa, A.Kuznetsov, V.Senik,  D. Vlasenko,
G.Antipov, D.Zimnukhov, E.Minkina, A.Chasovnikov, V.Topolev, D.Kuvshinov, D. Cheryasov, Ya.Kechin, Yu.Tselik, A. Sosnovskij
(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. Gress, N.M. Budnev, O.Ershova
(Irkutsk State University, API),

L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez
(INAOE, Guillermo Haro Astrophysics Observatory),

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

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

MASTER-Amur robotic telescope  (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L)  located in Russia (Blagoveshchensk State Pedagogical University) started inspect of the Fermi GRB 230913A ( Fermi GBM team, GCN 34680) errorbox  12289 sec after notice time and 12299 sec after trigger time at 2023-09-13 11:21:12 UT, with upper limit up to  18.5 mag. Observations started at twilight.  The observations began at zenith distance = 27 deg. The sun  altitude  is -14.7 deg. 

The galactic latitude b = 26 deg., longitude l = 111 deg.


Real time updated cover map and OT discovered available here: 
https://master.sai.msu.ru/site/master2/observ.php?id=2269810

We obtain a following upper limits.  

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

   12330 | 2023-09-13 11:21:12 |         MASTER-Amur | (19h 14m 13.35s , +77d 14m 05.4s) |   C |    60 | 18.5 |        
   12411 | 2023-09-13 11:22:33 |         MASTER-Amur | (19h 32m 21.13s , +76d 57m 30.6s) |   C |    60 | 18.4 |        
Filter C is a clear (unfiltred) band. 


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


GRB_name: GRB230913A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34683
SUBJECT: GRB 230913A: Swift/BAT-GUANO arcminute localization of a burst
DATE:    23/09/13 13:55:53 GMT
FROM:    Samuele Ronchini at PSU <sjs8171@psu.edu>

Samuele Ronchini (PSU), Jamie A. Kennea (PSU), James DeLaunay (U Alabama), Aaron Tohuvavohu (U Toronto), Gayathri Raman (PSU), Tyler Parsotan (NASA GSFC)  report:

Swift/BAT did not localize GRB 230913A onboard (T0: 2023-09-13T07:56:12.16 UTC, Fermi/GBM GCN 34680, CALET trigger 1378626813).

The Fermi and CALET notices, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). 

Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground.

The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), detects the burst in a 8.192 s analysis time bin with a sqrt(TS) of 19.7.
An arcminute localization is found with DeltaLLHOut of 64.99 and a DeltaLLHPeak of 60.07.

See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretations of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut.

The BAT position is
RA, Dec = 267.349, +74.484 deg (J2000) which is
RA (J2000)      17h 49m 23.8s
Dec (J2000)    74d 29m 2.4s
with an estimated uncertainty of 5 arcmin radius.

No XRT and UVOT follow-up can be done due to observational constraints. 
We strongly encourage follow-up from other telescopes.

GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.

A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/


GRB_name: GRB230911A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34684
SUBJECT: GRB 230911A: Swift ToO observations
DATE:    23/09/13 14:57:43 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

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

Swift has initiated a ToO observation of the Fermi/GBM GRB 230911A. 
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021622

Any uncatalogued X-ray sources detected in this analysis will be
reported on this website and via GCN COUNTERPART notices. These are
not necessarily related to the Fermi/GBM 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: GRB230913A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34689
SUBJECT: GRB 230913A: Fermi GBM Observation
DATE:    23/09/13 21:26:08 GMT
FROM:    Sarah Dalessi at UAH <sd0104@uah.edu>

S. Dalessi (UAH), R. Hamburg (CNRS/IJCLab), and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 07:56:12.16 UT on 13 September 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230913A (trigger 716284577/230913331).
which was also detected by Swift/BAT GUANO (S. Ronchini et al. 2023, GCN 34683).
The Fermi GBM Final Real-time Localization was reported in GCN 34680.

The angle from the Fermi LAT boresight is 41 degrees.

The GBM light curve single peak with a duration (T90)
of about 12 s (50-300 keV). The time-averaged spectrum
from T0-1.0 to T0+9.2 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.1 +/- 0.2 and the cutoff energy,
parameterized as Epeak, is 160 +/- 10 keV.

The event fluence (10-1000 keV) in this time interval is
(3.1 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+1.3 s in the 10-1000 keV band is 2.1 +/- 0.2 ph/s/cm^2.

A Band function fits the spectrum equally well
with Epeak= 130 +/- 20 keV, alpha = 0.3 +/- 0.4 and beta = -2.3 +/- 0.2.

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: GRB230812B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34694
SUBJECT: GRB 230812B: Bad Time Intervals for Fermi GBM data
DATE:    23/09/14 15:17:04 GMT
FROM:    Oliver J Roberts at USRA/NASA <oliver.roberts@nasa.gov>

O.J. Roberts (USRA), S. Lesage (UAH) and W. Cleveland (USRA) report on behalf of the Fermi GBM Team: 

"The Fermi Gamma-ray Burst Monitor data for GRB 230812B has a period of bad time intervals, affecting all data types and all detectors. At particularly high rates, the Time-Tagged Event (TTE) data has data-loss due to the bandwidth limit between the instrument and the spacecraft. CTIME and CSPEC data do not experience data-loss due to the electronics bandwidth, but do experience deadtime effects. Additionally, at particularly high rates both CTIME and CSPEC are affected by pulse pile-up, which will distort the spectra (see, S. Lesage et al., 2023, ApJL, 952, L42). 

Due to the orientation of the burst, we recommend only using BGO detector: B0, and the NaI detectors: N0, N3, N6, N7 for any analysis of this burst, as all other detectors either have an unfavorable detector-source angle (>60 degrees), or are blocked by different parts of the spacecraft.

For CTIME and CSPEC data of these detectors, pulse pile-up occurs during the time intervals of T0+0.61 to T0+1.12 seconds for the BGO detector, B0. We find pulse pile-up occurs from T0+0.54 to T0+1.70 seconds for the NaI detectors N0, N3, N6, N7. T0 is the GBM trigger time.

In the TTE data, data losses due to the bandwidth limit being exceeded occurs between roughly T0+0.5 to T0+1.4 seconds. This region includes the artificially created pulse centered at roughly T0+1.233 seconds (width of approximately 0.098 seconds), that is due to TTE drop out. We are currently reprocessing the TTE files and will alert the community when these files become available in a forthcoming circular. 

We recommend the exclusion of these time intervals for GBM analysis of this burst, as well as caution using bins adjacent to these selections."


GRB_name: GRB230913A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34696
SUBJECT: GRB 230913A: Glowbug gamma-ray detection
DATE:    23/09/14 21:40:12 GMT
FROM:    matthew.kerr@gmail.com

M. Kerr, C.C. Cheung, J. E. Grove, R. Woolf (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge (MSFC), and M.S. Briggs (UAH) report:

The Glowbug gamma-ray telescope [1,2], operating on the International Space Station, reports the detection of GRB 230913A, which was also detected by Fermi/GBM, CALET, and Swift/BAT-GUANO (GCN 34680, 34683)
 
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2023-09-13 07:56:06.008 with a duration of 12.3 s and a total significance of about 22.2 sigma.
 
Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission over this duration results in a photon index dN/dE~E^x of x=2.0 and a cutoff energy ("Epeak") of 152 keV.  The modeled 10-10000 keV fluence is 7.7e-07 erg/cm^2.
 
The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.
 
Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC.  It was launched on 2023 March 15 aboard the Department of Defense Space Test Programâ€™s STP-H9 to the ISS.  The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.
 
[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006
 
Distribution Statement A: Approved for public release.  Distribution is unlimited.


GRB_name: GRB230913A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34700
SUBJECT: GRB 230913A: CALET Gamma-Ray Burst Monitor detection
DATE:    23/09/15 03:21:21 GMT
FROM:    Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>

M. L. Cherry (LSU), A. Yoshida, T. Sakamoto, S. Sugita (AGU),
Y. Kawakubo (LSU), K. Yamaoka (Nagoya U), S. Nakahira (JAXA),
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 GRB 230913A (Fermi GBM Final Real-time Localization: 
Fermi GBM team, GCN Circ. 34680; Swift/BAT-GUANO arcminute 
localization, Ronchini et al., GCN Circ. 34683; Fermi GBM Observation:
Dalessi et al., GCN Circ. 34689; Glowbug gamma-ray detection: Kerr et al.,
GCN Circ. 34696) triggered the CALET Gamma-ray Burst Monitor (CGBM) 
at 07:56:11.95 UTC on 13 September 2023
(http://cgbm.calet.jp/cgbm_trigger/flight/1378626813/index.html).
The burst signal was seen by all CGBM detectors.

The burst light curve shows a single pulse that starts
at T+0.9 sec, peaks at T+1.5 sec, and ends at T+4.4 sec.
The T90 and T50 durations measured by the SGM data are 3.1 +/- 0.3 sec
and 1.9 +/- 0.4 sec (40-1000 keV), respectively.

The ground-processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1378626813/

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


GRB_name: GRB230911A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34702
SUBJECT: GRB 230911A: Swift-XRT afterglow detection
DATE:    23/09/15 06:29:37 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

P. D'Avanzo (INAF-OAB), D.N. Burrows (PSU), J. D. Gropp (PSU), S.
Dichiara (PSU), A.P. Beardmore (U. Leicester), J.P. Osborne (U.
Leicester), M.G. Bernardini (INAF-OAB), E. Ambrosi  (INAF-IASFPA)  and
P.A. Evans (U. Leicester) reports on behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Fermi/GBM-detected burst GRB 230911A, collecting 2.8 ks of Photon
Counting (PC) mode data between T0+215.5 ks and T0+326.2 ks. 

An uncatalogued X-ray source is detected consistent with the GOTO
position (GCN Circ. 34681) of the fading optical counterpart candidate,
and this is therefore believed to be the afterglow.  The position of
this source (astrometrically enhanced by using the XRT-UVOT alignment
and matching UVOT field sources to the USNO-B1 catalogue) is RA,
Dec=57.5027, -29.8259 which is equivalent to:

RA (J2000): 03:50:0.65
Dec(J2000): -29:49:33.2

with an uncertainty of 3.4 arcsec (radius, 90% confidence). Position
enhancement is described by Goad et al. (2007, A&A, 476, 1401) and
Evans et al. (2009, MNRAS, 397, 177). This position is 3.1 arcsec from
the GOTO position.  

The results of the XRT-team automatic analysis are available at
http://www.swift.ac.uk/xrt_products/00021622.
The results of the full analysis of the XRT observations are available
at https://www.swift.ac.uk/ToO_GRBs/00021622.

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


GRB_name: GRB230906A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34704
SUBJECT: GRB 230906A: optical counterpart
DATE:    23/09/15 21:21:52 GMT
FROM:    corinna.pena@utah.edu

C. PeÃ±a (Univ. of Utah), D.  B. Malesani (Radboud univ. and DAWN/NBI), A. Rossi (INAF), A. J. Levan (Radboud univ.), and G. Pugliese (API, Amsterdam), report on behalf of the Stargate collaboration:

Following the Chandra X-ray localization (Oâ€™Connor et al., GCN 34672) of the Fermi/GBM short GRB 230906A (Fermi GBM team, GCN 34631; Frederiks et al., GCN 34638), we observed the GRB afterglow with the ESO Very Large Telescope equipped with the HAWK-I near infrared camera and with the FORS2 optical camera. Observations in the HAWK-I Ks band consisted in 30 minute exposure with a mean time of 6.84 days after the GRB. Observations in the FORS2 R band consisted in 40 minute exposure with a mean time of 6.76 days after the GRB. Sky conditions were modest, with a delivered seeing of ~2" in the R band.

Consistent with the position of the X-ray afterglow discovered by Chandra (Oâ€™Connor et al., GCN 34672), we detect a weak source in the stacked R-band image, at J2000 coordinates (~0.5" error):

RA = 05:19:01.57
Dec = -47:53:32.3

We measure for this source an AB magnitude R = 25.44 Â± 0.25, calibrated against nearby SkyMapper stars. In the Ks band, we can only set an upper limit with AB magnitude > 23.3. As noted by Oâ€™Connor et al. (GCN 34672), there is no detected host galaxy in the Legacy Survey, which has however a depth shallower than our measurement.

While the spatial association with the X-ray counterpart suggests a physical connection with the GRB, it is unclear whether the source is dominated by transient light or is a faint host galaxy. We note that the R-K color is not as red as was AT 2017gfo at a comparable epoch after explosion (e.g. Villar et al. 2017, ApJ, 851, L21).

We acknowledge the support of the observing staff at Paranal, in particular Ana Escorza, Linda Schmidtobreick, and Fuyan Bian.


GRB_name: GRB230911D
Detection_method: Fermi LAT Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34712
SUBJECT: GRB 230911D: GRBAlpha detection
DATE:    23/09/16 16:00:54 GMT
FROM:    Marianna DafÄÃ­kovÃ¡ at Masaryk University <500025@mail.muni.cz>

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

The long-duration GRB 230911D (Fermi/GBM detection: GCN 34656; Fermi/LAT detection: GCN 34668; Konus/Wind detection: GCN 34659; NuSTAR detection: GCN 34678; INTEGRAL/SPI-ACS peak detection at 2023-09-11 ~07:53:25 UT) was observed by the GRBAlpha 1U CubeSat (Pal et al. 2023; arXiv:2302.10048).

The detection was confirmed at the peak time 2023-09-11 07:53:26 UTC. The T90 duration measured by GRBAlpha is 45 s and the overall significance during T90 reaches 56 sigma.

The light curve obtained by GRBAlpha is available here: 
https://grbalpha.konkoly.hu/static/share/GRB230911D_GCN.pdf

All GRBAlpha detections are listed at: https://monoceros.physics.muni.cz/hea/GRBAlpha/ 
GRBAlpha, launched on 2021 March 22, is a demonstration mission for a future CubeSat constellation (Werner et al. Proc. SPIE 2018). The detector of GRBAlpha consists of a 75 x 75 x 5 mm3 CsI scintillator read out by a SiPM array, covering the energy range from ~50 keV to ~1000 keV. To increase the duty cycle and the downlink rate, the upgrade of the on-board data acquisition software stack is in progress. The ground segment is also supported by the radio amateur community and it takes advantage of the SatNOGS network for increased data downlink volume. 


GRB_name: GRB230915A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34714
SUBJECT: GRB 230915A: Swift/BAT-GUANO detection of a burst
DATE:    23/09/16 19:21:26 GMT
FROM:    Samuele Ronchini at PSU <sjs8171@psu.edu>

Aaron Tohuvavohu (U Toronto), James DeLaunay (UAlabama), Gayathri Raman (PSU), Samuele Ronchini (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report:

Swift/BAT did not localize GRB 230915A onboard (T0: 2023-09-15T05:39:29.46 UTC, Fermi GBM Trig 716449174). 

The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). 

Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground.

The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), detects the burst with a sqrt(TS) of 11.3 in a 8.192 s analysis time bin, starting at T0 + 2.0482 s.

NITRATES results, independently, are ambiguous with respect to whether this burst originates from in or outside the BAT coded FOV, with a DeltaLLHOut of 10.49.

See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut.

GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.

A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/


GRB_name: GRB230911A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34720
SUBJECT: GRB 230911A: Fermi GBM Observation
DATE:    23/09/17 00:27:58 GMT
FROM:    Oliver J Roberts at USRA/NASA <oliver.roberts@nasa.gov>

O.J. Roberts (USRA/NASA-MSFC) and C. Meegan (UAH)
report on behalf of the Fermi Gamma-ray Burst Monitor Team:

"At 03:09:32.88 UT on 11 September 2023, the
Fermi Gamma-ray Burst Monitor (GBM) triggered and located
GRB 230911A (trigger 716094577/230911132), which was also
detected by Swift/XRT (P. D'Avanzo et al. 2023, GCN 34702)
and GOTO (S. Belkin et al. 2023, GCN 34681). The Fermi GBM
Final Real-time Localization reported in GCN 34652 is
consistent with the Swift-XRT and GOTO localizations.

The angle from the Fermi LAT boresight is 54 degrees.

The GBM light curve consists of a single peak with a
duration (T90) of about 36 s (50-300 keV). The time-averaged
spectrum from T0-4 to T0+30 s is best fit by a Band function
with Epeak= 98 +/- 21 keV, alpha = -1.1 +/- 0.1 and
beta = -2.0 +/- 0.1.

The event fluence (10-1000 keV) in this time interval is
(6.2 +/- 0.3)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+2.0 s in the 10-1000 keV band is 3.7 +/- 0.2 ph/s/cm^2.

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

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


GRB_name: GRB230916A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34721
SUBJECT: GRB 230916A: NuSTAR Discovery of Prompt Emission from a Potential GRB
DATE:    23/09/17 17:39:34 GMT
FROM:    Brian Grefenstette at Caltech/NuSTAR <bwgref@srl.caltech.edu>

B. Grefenstette reports on behalf of the NuSTAR Search for INteresting Gamma-ray Signals (SINGS) working group:

The NuSTAR SINGS working group reports the discovery of prompt emission from a potential GRB 230916A in the NuSTAR CsI anti-coincidence shields. This GRB was identified through a blind search using the CsI shield rates. Details of the search algorithm will be described in a future paper. 

The CsI data are recorded at 1 Hz and show a broad burst with a single peak. 1-sec count rates peaked at >10,000 counts per second in both the FPMA and FPMB shield units. Typical background rates are ~1,000 counts per second. The peak of the burst is unresolved (e.g., shorter than the 1-s bins) with a decay back to quiescence of ~5-s. Offline analysis shows that the peak time was 2023-09-16T13:28:47.5. As no other instrument has yet reported this burst we cannot rule out a non-astrophysical origin. However, the fact that both CsI shields show the peak and show similar decay rates are suggestive of an astrophysical origin.

The burst was not detected in either of the CdZnTe detectors.

The NuSTAR data alone are insufficient to provide any localization information for this burst.

The automated light curve report for this GRB, discovery report, and off-line analysis of the shield rates to determine the peak time can be found here.

https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/reports/2023/230916A/

Information on NuSTAR SINGS can be found here: 

https://nustarsoc.caltech.edu/NuSTAR_Public/grbs/

NuSTAR is a NASA Small Explorer mission led by Caltech and managed by JPL for NASAâ€™s Science Mission Directorate in Washington. 


GRB_name: GRB230915B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34722
SUBJECT: GRB 230915B:  Glowbug gamma-ray detection
DATE:    23/09/18 00:17:43 GMT
FROM:    J. Eric Grove at U.S. Naval Research Laboratory <eric.grove@nrl.navy.mil>

J.E. Grove, C.C. Cheung, M. Kerr, R. Woolf (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge (MSFC), and M.S. Briggs (UAH) report:

The Glowbug gamma-ray telescope [1,2], operating on the International Space Station, reports the detection of GRB 230915B.

Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2023-09-15 06:54:23.792 with a duration of 12.3 s and a total significance of about 18.7 sigma.  The light curve comprises a single broad peak.

Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission over this duration results in a photon index dN/dE~E^x of x=2.5 and a cutoff energy ("Epeak") of 208 keV.  The modeled 10-10000 keV fluence is 1.2e-06 erg/cm^2.

The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.

Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC.  It was launched on 2023 March 15 aboard the Department of Defense Space Test Programâ€™s STP-H9 to the ISS.  The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.

[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006

Distribution Statement A: Approved for public release.  Distribution is unlimited.


GRB_name: GRB230917A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34725
SUBJECT: GRB 230917A: AstroSat CZTI detection
DATE:    23/09/18 05:19:36 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

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

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long-duration GRB 230917A which was also detected by KONUS-Wind (reported in IPN_RAW GCN notices).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2023-09-17 00:44:43.5 UTC. The measured peak count rate associated with the burst is 217 (+42, -30) counts/s above the background in the combined data of all quadrants, with a total of 2685 (+700, -606) counts. The local mean background count rate was 409 (+2, -3) counts/s. Using cumulative rates, we measure a T90 of 67 (+11, -4) s.

The source 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 2023-09-17 00:44:44.6 UTC. The measured peak count rate associated with the burst is 427 (+67, -68) counts/s above the background in the combined data of all quadrants, with a total of 5334 (+1141, -1259) counts. The local mean background count rate was 1296 (+2, -4) counts/s. We measure a T90 of 89 (+24, -15) s from the cumulative Veto light curve.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230918A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34726
SUBJECT: GRB 230918A: Fermi GBM Final Real-time Localization
DATE:    23/09/18 10:03:09 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

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

At 09:52:36 UT on 18 Sep 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230918A (trigger 716723561.504536 / 230918412).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 222.5, Dec = -11.6 (J2000 degrees, equivalent to J2000 14h 50m, -11d 35'), with a statistical uncertainty of 17.1 degrees.

The angle from the Fermi LAT boresight is 63.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230918412/quicklook/glg_skymap_all_bn230918412.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230918412/quicklook/glg_healpix_all_bn230918412.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230918412/quicklook/glg_lc_medres34_bn230918412.gif


GRB_name: GRB230812B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34727
SUBJECT: GRB 230812B: Radio observations with the uGMRT
DATE:    23/09/18 11:41:40 GMT
FROM:    S. Mohnani at Indian Institute Of Technology Indore <phd2201121011@iiti.ac.in>

S. Mohnani (IIT Indore), S. Chatterjee (IIT Indore), B. Banerjee (GSSI), A. Shukla (IIT Indore), A. Datta (IIT Indore),  G. Oganesyan (GSSI), S. Agarwal (IIT Indore), M. Branchesi (GSSI), K.K Yadav (ApSD BARC), V. Chitnis (TIFR), G.C. Anupama (IIA), P. Tiwari (GSSI), S. Mangla (IIT Indore)
  
At 11:30:00 UT on 2023 September 17 (35.92 days post-burst) upgraded Giant Meterwave Radio Telescope (uGMRT) observed the field of GRB 230812B (Fermi GBM team, GCN 34386) at a central frequency of 1.26 GHz for about 2 hours.

The standard 3C286 was used as a bandpass and flux density calibrator, while 1635+381 was used as a phase calibrator.

Based on preliminary analysis, we do not detect any source consistent with the location of the afterglow (A.P. Beardmore et al., GCN 34400; S. Giarratana et al., GCN 34552). The 3-sigma upper limit achieved is ~ 43 micro Jy.

We would like to thank the staff of the uGMRT for approving, executing,
and processing the observations through the DDT proposal (ddtC304; PI- Shraddha Mohnani).

The uGMRT is operated by the National Center for Radio Astrophysics of the Tata Institute of Fundamental Research.


GRB_name: GRB230915A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34729
SUBJECT: GRB 230915A: Fermi GBM observation
DATE:    23/09/18 14:43:46 GMT
FROM:    rachel.hamburg@ijclab.in2p3.fr

R. Hamburg (CNRS/IJCLab) and C. Meegan (UAH)
report on behalf of the Fermi GBM Team:

"At 05:39:29.46 UT on 15 September 2023, the Fermi Gamma-Ray Burst Monitor (GBM)
triggered and located GRB 230915A (trigger 716449174 / 230915236),
which was also detected by Swift/BAT-GUANO (Tohuvavohu et al. 2023, GCN 34714)

The angle from the Fermi LAT boresight at the GBM trigger time is 56 degrees.

The GBM light curve shows a multi-peaked lightcurve
with a duration (T90) of about 42 s (50-300 keV).
The time-averaged spectrum from T0-9.73 s to T0+18.94 s is
best fit by a power law function with an exponential
high-energy cutoff.  The power law index is -1.13 +/- 0.06 and
the cutoff energy, parameterized as Epeak, is 177 +/- 19 keV.
A Band function fits the spectrum equally well with
Epeak = 141 +/- 23 keV, alpha = -1.03 +/- 0.10 and beta = -2.18 +/- 0.20.

The event fluence (10-1000 keV) in this time interval is
(5.60 +/- 0.29)E-06 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+4.54 s in the 10-1000 keV band
is 5.3 +/- 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: GRB230916B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34732
SUBJECT:  GRB 230916B: Glowbug gamma-ray detection
DATE:    23/09/18 22:19:51 GMT
FROM:    matthew.kerr@gmail.com

M. Kerr, C.C. Cheung, J. E. Grove, R. Woolf (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge (MSFC), and M.S. Briggs (UAH) report:

The Glowbug gamma-ray telescope [1,2], operating on the International Space Station, reports the detection of GRB 230916B, which was also detected by Fermi/GBM (trigger 716572242).

Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2023-09-16 15:50:37.040 with a duration of 14.3 s and a total significance of about 32.9 sigma.

Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission over this duration results in a photon index dN/dE~E^x of x=3.3 and a cutoff energy ("Epeak") of 94 keV.  The modeled 10-10000 keV fluence is 1.0e-06 erg/cm^2.

The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.

Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC.  It was launched on 2023 March 15 aboard the Department of Defense Space Test Programâ€™s STP-H9 to the ISS.  The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.

[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006

Distribution Statement A: Approved for public release.  Distribution is unlimited.


GRB_name: GRB230918A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34733
SUBJECT: GRB 230918A (short): Glowbug gamma-ray detection
DATE:    23/09/18 22:20:21 GMT
FROM:    matthew.kerr@gmail.com

M. Kerr, C.C. Cheung, J. E. Grove, R. Woolf (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge (MSFC), and M.S. Briggs (UAH) report:

The Glowbug gamma-ray telescope [1,2], operating on the International Space Station, reports the detection of the short GRB 230918A, which was also detected by Fermi/GBM (GCN 34726).

Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2023-09-18 09:52:35.360 with a duration of 0.128 s and a total significance of about 12.9 sigma.

Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission over this duration results in a photon index dN/dE~E^x of x=0.7 and a cutoff energy ("Epeak") of 417 keV.  The modeled 10-10000 keV fluence is 1.7e-07 erg/cm^2.

The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.

Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC.  It was launched on 2023 March 15 aboard the Department of Defense Space Test Programâ€™s STP-H9 to the ISS.  The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.

[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006

Distribution Statement A: Approved for public release.  Distribution is unlimited.


GRB_name: GRB230918B
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34734
SUBJECT: GRB 230918B: Fermi GBM Final Real-time Localization
DATE:    23/09/19 00:05:51 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

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

At 23:55:14 UT on 18 Sep 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230918B (trigger 716774119.92359 / 230918997).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 307.7, Dec = -48.4 (J2000 degrees, equivalent to J2000 20h 30m, -48d 23'), with a statistical uncertainty of 6.3 degrees.

The angle from the Fermi LAT boresight is 47.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230918997/quicklook/glg_skymap_all_bn230918997.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230918997/quicklook/glg_healpix_all_bn230918997.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230918997/quicklook/glg_lc_medres34_bn230918997.gif


GRB_name: GRB230812B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34735
SUBJECT: Detection of self-absorbed radio emission from GRB 230812B with the JVLA + uGMRT
DATE:    23/09/19 03:00:15 GMT
FROM:    pchandra@nrao.edu

Poonam Chandra (NRAO), Tomas Ahumada (UMD), Varun Bhalerao (IITB), Gaurav Waratkar (IITB), Gokul Srinivasaragavan (UMD), Suchindram Dasgupta (Rutgers), Mansi Kasliwal (Caltech), Shreya Anand (Caltech), Viswajit Swain (IITB), David Kaplan (UWM),  Harsh Kumar (IITB) and Daniel Perley (LJMU) report on behalf of a larger collaboration:

We observed GRB 230812B (Fermi GBM Team, GCN Circ. 34386) with Karl G. Jansky Very Large Array on Sep 2, 2023 during 18:24:52 - 19:53:33 UT (proposal # 23B-292) in X (8-12 GHz), C (4-8 GHz) and S (2-4 GHz) bands and with the upgraded Giant Metrewave Radio Telescope (uGMRT)  on Sep 17, 2023, 11:30:00 UT (proposal # DDT C305)  in band 5 (1000-1450 MHz). We detect the GRB in the three  observed JVLA bands with S, C, X bands flux densities to be  30.6+/-11.2, 49.2+/-7.9 uJy and 28.2+/-10.1 uJy, respectively. The GRB is not detected in the uGMRT band 5 with a 3-sigma upper limit of ~40 uJy, consistent with the results of Mohnani et al., (GCN Circ. 34727). This indicates that the GRB is in the optically thin regime at  C band and higher frequencies, however, it is self-absorbed at lower frequencies, i.e. JVLA S band and the uGMRT band 5.

We thank the VLA and GMRT staff for carrying out the observations. The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc.  GMRT is run by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research. More observations are planned. 


GRB_name: GRB230919A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34737
SUBJECT: GRB 230919A: Fermi GBM Final Real-time Localization
DATE:    23/09/19 17:06:22 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

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

At 16:58:23 UT on 19 Sep 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230919A (trigger 716835508.857072 / 230919707).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 58.2, Dec = 41.2 (J2000 degrees, equivalent to J2000 03h 52m, 41d 12'), with a statistical uncertainty of 6.7 degrees.

The angle from the Fermi LAT boresight is 120.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230919707/quicklook/glg_skymap_all_bn230919707.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230919707/quicklook/glg_healpix_all_bn230919707.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230919707/quicklook/glg_lc_medres34_bn230919707.gif


GRB_name: GRB230918B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34738
SUBJECT: GRB 230918B: GOTO detection of a fast-rising transient in the GBM localisation region
DATE:    23/09/19 20:58:28 GMT
FROM:    Ben Gompertz at U of Birmingham <b.gompertz@bham.ac.uk>

B. P. Gompertz; M. R. Kennedy; D. O'Neill; K. Ulaczyk; T. Killestein; K. Ackley; D. B. Malesani; R. Starling; M. J. Dyer; J. Lyman; F. Jimenez-Ibarra; A. Kumar; D. Steeghs; D. K. Galloway; V. Dhillon; P. O'Brien; G. Ramsay; K. Noysena; R. Kotak; R. P. Breton; L. K. Nuttall; E. Pall'e and D. Pollacco report on behalf of the GOTO collaboration:

We report on observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022) in response to GRB 230918B (Fermi GBM team, GCN 34734). Three targeted observations were performed by GOTO-South between 09:15:23 UT and 11:31:06 UT on 2023-09-19, corresponding to 0.39, 0.44 and 0.48 days after trigger. Each observation consisted of 4x90 s exposures in the GOTO L-band (400-700 nm).

Images were processed immediately after acquisition using the GOTO pipeline. Difference imaging was performed using recent survey observations of the same pointings. Source candidates were initially filtered using a classifier (Killestein et al. 2021) and cross-matched against a variety of contextual and minor planet catalogues. Human vetting was carried out in real time on any candidates that passed the above checks.

We identify a fast-rising optical source within the GBM 90% localisation region:

Name | RA(J2000) | Dec(J2000)
GOTO23aky | 20:54:37.14 | -48:40:29.33

The L-band AB magnitudes at each epoch are measured to be 20.34 +/- 0.16, 20.18 +/- 0.11, and 20.03 +/- 0.10, respectively. This corresponds to a rise of 3.3 +/- 2.0 mag/day.

We find no evidence of this source prior to the GRB trigger time in previous GOTO observations (taken ~6 days prior to the GRB) or the ATLAS forced photometry server (Shingles et al. 2021, taken ~ 1 day prior to the GRB). No underlying source is present at the position in the Legacy Server (Dey et al. 2019).

Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction.

GOTO (https://goto-observatory.org) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC).


GRB_name: GRB230919A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34742
SUBJECT: GRB 230919A: AstroSat CZTI detection
DATE:    23/09/20 13:42:29 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

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

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of GRB 230919A which was also detected by Fermi-GBM (Fermi GBM Team, GCN Circ. 34737).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2023-09-19 16:58:23.95 UTC. The measured peak count rate associated with the burst is 1118 (+205, -166) counts/s above the background in the combined data of all quadrants, with a total of 921 (+115, -92) counts. The local mean background count rate was 406 (+10, -15) counts/s. Using cumulative rates, we measure a T90 of 1.58 (+1.38, -0.23) s. We caution that there are two 0.3 s readout dead time windows in CZTI data immediately after the detection of the burst. Hence, the T90 can be as large as 2.96 s for this GRB, with a lower limit of 1.35 s as estimated above by cumulative rates.

The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2023-09-19 16:58:23.55 UTC. The measured peak count rate associated with the burst is 1196 (+82, -86) counts/s above the background in the combined data of all quadrants, with a total of 1796 (+193, -200) counts. The local mean background count rate was 1280 (+6, -6) counts/s. We measure a T90 of 2.1 (+1.2, -0.5) s from the cumulative Veto light curve. Note that this result is limited due to the 1 s native resolution of veto data.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB230812B
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34743
SUBJECT: GRB 230812B : optical observations from MISTRAL at Observatoire de Haute-Provence
DATE:    23/09/20 16:25:03 GMT
FROM:    christophe.adami@lam.fr

C. Adami, P. Amram, S. Basa, K. Parra-Ramos (LAM), T. Adami (ENS Paris-Saclay), B. Schneider (MIT), A. Saccardi, S. D. Vergani, (GEPI, Obs. de Paris), S. Antier, A. de Ugarte Postigo (OCA), 
E. Le Floc'h, D. GÃ¶tz, F. SchÃ¼ssler, D. Turpin (CEA-Saclay), report, on behalf of a larger collaboration:

We observed the field of GRB 230812B (Fermi GBM Team GCN, 34386 and all subsequent GCNs) using the MISTRAL spectro-imager of Observatoire de Haute Provence (OHP) in imaging mode. We obtained 
during the 2023 09 17 night 1x1200s exposure in the r'-band with a mid-epoch of 19:20 UT, during the 2023 09 18 night 1x600s and 2x900s exposures in the r'-band with a mid-epoch of 21:06 UT, and during the 2023 09 19
night 8x600sec and 1x700sec in the r'-band with a mid epoch of 19:58 UT.

We derive the following photometry, calibrated against the Pan-STARRS catalog, not corrected for the underlying galaxy, and not corrected for Galactic dust reddening:


2023 09 17 19:20 UT r' = 22.36 +/- 0.16
2023 09 18 21:06 UT r' = 22.37 +/- 0.14
2023 09 19 19:58 UT r' = 22.45 +/- 0.10


We acknowledge the excellent support from Jerome Schmitt, Stephane Favard and Jean Balcaen (Observatoire de Haute Provence).


GRB_name: GRB230919A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34747
SUBJECT: GRB 230919A: Swift/BAT-GUANO detection of a possibly short burst outside the coded FOV 
DATE:    23/09/20 17:51:55 GMT
FROM:    Jimmy DeLaunay at University of Alabama  <delauj2@gmail.com>

James DeLaunay (U Alabama), Aaron Tohuvavohu (U Toronto), Samuele Ronchini (PSU), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC) report: 

Swift/BAT did not localize GRB 230919A onboard (T0: 2023-09-19T16:58:23.86 UTC, Fermi trig 716835508, AstroSat CZTI GCN 34742) 

The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). 

Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 90 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground. 

The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 16.6 in a 1.5 s analysis time bin, starting at T0 - 0.2 s. 

NITRATES results are consistent with a burst coming from outside the FOV, with DeltaLLHOut of -0.6 and are consistent with Fermi GBM's localization (GCN 34737).

See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretation of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut. 

GUANO is a fully autonomous, extremely low latency, spacecraft commanding pipeline designed for targeted recovery of BAT event mode data around the times of compelling astrophysical events to enable more sensitive GRB searches. 

A live reporting of Swift/BAT event data recovered by GUANO can be found at: https://www.swift.psu.edu/guano/


GRB_name: GRB230919A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34750
SUBJECT: GRB 230919A: Fermi GBM Observation
DATE:    23/09/20 20:49:41 GMT
FROM:    Lorenzo Scotton at UAH <lscottongcn@outlook.com>

L. Scotton (UAH), C. Fletcher (USRA) and C. Meegan (UAH) report on behalf of
the Fermi Gamma-ray Burst Monitor Team:

"At 16:58:23.86 UT on 19 September 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 230919A (trigger 716835508/230919707).
which was also detected by AstroSat (Navaneeth et al. 2023, GCN 34742)
and Swift/BAT-GUANO (DeLaunay et al. 2023, GCN 34747).

The Fermi GBM Final Real-time Localization was reported in GCN 34737.

The angle from the Fermi LAT boresight is 120 degrees.

The GBM light curve consists of multiple peaks 
with a duration (T90) of about 2.9s. The time-averaged spectrum
from T0-0.06 to T0+1.34 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -0.74 +/- 0.06 and the cutoff energy,
parameterized as Epeak, is 2023 +/- 271 keV. 
A Band function fits the spectrum equally well with
Epeak = 1617 +/- 352 keV, alpha = -0.68 +/- 0.08 and beta = -2.43 +/- 0.32.

The event fluence (10-1000 keV) in this time interval is
(3.3 +/- 0.1)E-06 erg/cm^2. The 64-msec peak photon flux measured
starting from T0+0.58 s in the 10-1000 keV band is 12 +/- 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: GRB230919A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34752
SUBJECT: IPN triangulation of GRB 230919A (short)
DATE:    23/09/20 21:46:04 GMT
FROM:    Anna Ridnaia at Ioffe Institute <ridnaia@mail.ioffe.ru>

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

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

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

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

and

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

The short-duration GRB 230919A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 34737;
Scotton et al., GCN Circ. 34750;
AstroSat CZTI detection: Navaneeth et al., GCN Circ. 34742;
Swift/BAT-GUANO detection: DeLaunay et al., GCN Circ. 34747)
has been detected by Fermi (GBM trigger 716835508), Konus-Wind,
Mars-Odyssey (HEND), Swift (BAT), and AstroSat (CZTI),
so far, at about 61103 s UT (16:58:23).
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:
   71.620 (04h 46m 29s) +44.076 (+44d 04' 35")
 Corners:
   70.812 (04h 43m 15s) +45.562 (+45d 33' 43")
   70.802 (04h 43m 12s) +45.703 (+45d 42' 10")
   72.402 (04h 49m 37s) +42.484 (+42d 29' 04")
   72.411 (04h 49m 39s) +42.324 (+42d 19' 28")
 ---------------------------------------------
The error box area is 543 sq. arcmin, and its maximum
dimension is 3.6 deg (the minimum one is 3 arcmin).
The Sun distance was 100 deg.

The IPN localization is consistent with, but reduces the area of,
the Fermi-GBM final localization (GCN Circ. 34737).

This localization may be improved.

A triangulation map and HEALPix FITS file are posted at
http://www.ioffe.ru/LEA/GRBs/GRB230919_T61103/IPN/

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


GRB_name: GRB230918B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34753
SUBJECT: GRB 230918B: VLT/X-shooter classification of AT 2023tbf (GOTO23aky) as a dwarf nova
DATE:    23/09/20 22:32:36 GMT
FROM:    Daniele B. Malesani at IMAPP / Radboud University <d.malesani@astro.ru.nl>

A. Saccardi (GEPI/Paris Obs.), L. Izzo (INAF/OACn & DARK/NBI), J. T. Palmerio (GEPI/Paris Obs. & IAP), D. B. Malesani (Radboud Univ. & DAWN/NBI), P. D'Avanzo (INAF-OABr), V. Dâ€™Elia (ASI-SSDC & INAF-OAR), M. Della Valle (INAF/OAC), D. H. Hartmann (Clemson Univ.),  K. E. Heintz (DAWN/NBI), P. Jakobsson (U. of Iceland), L. Kaper (U. of Amsterdam), G. Leloudas (DTU Space), A. J. Levan (Radboud Univ.), A. Martin-Carrillo (UCD), B. Schneider (MIT), S. Schulze (OKC), A. de Ugarte Postigo (OCA), and K. Wiersema (U. of Hertfordshire) report on behalf of the Stargate collaboration:

We observed the transient AT 2023tbf (GOTO23aky; Gompertz et al., GCN 34738), spatially and temporally consistent with the Fermi GBM GRB 230918B (Fermi GBM team; GCN 34734). We used the ESO VLT UT3 (Melipal) equipped with the X-shooter spectrograph, starting on 2023 September 20.093 UT. Our data cover the wavelength range 3000-24800 AA and consist of 4 exposures of 600 s each.

In the acquisition image, taken on 2023 Sep 20.086 UT, we measure for the transient a magnitude r = 19.64 +- 0.05 AB (calibrated against a single nearby star from the SkyMapper catalog).

A strong continuum is detected in the blue end of the spectrum, with a decreasing signal towards the VIS and NIR arms. The UVB shows several broad undulations, not seen in GRB afterglow spectra; in the VIS and NIR arms, the continuum is smoother.

The source shows narrow absorption from Ca H and K a z = 0, as well as broad features in correspondence of the Balmer lines, at least H-beta to H-eta, all at z = 0. No features are identified at z > 0. Comparison with template spectra (e.g. Morales-Rueda & Marsh, 2002, MNRAS, 332, 814) allows us to classify AT 2023tbf as a dwarf nova. We thus conclude that AT 2023tbf is not a GRB afterglow and is not associated with GRB 230918B.

We acknowledge excellent support from the observing staff at Paranal, in particular Ditte Slumstrup, Xavier Haubois, Francisco Caceres and Paulina Venegas. 


GRB_name: GRB230921A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34754
SUBJECT: GRB 230921A: Fermi GBM Final Real-time Localization
DATE:    23/09/21 02:51:55 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 02:41:32 UT on 21 Sep 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230921A (trigger 716956897.615146 / 230921112).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 239.4, Dec = -33.4 (J2000 degrees, equivalent to J2000 15h 57m, -33d 23'), with a statistical uncertainty of 6.9 degrees.

The angle from the Fermi LAT boresight is 39.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230921112/quicklook/glg_skymap_all_bn230921112.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230921112/quicklook/glg_healpix_all_bn230921112.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230921112/quicklook/glg_lc_medres34_bn230921112.gif


GRB_name: GRB230812B
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34762
SUBJECT: GRB 230812B: r'-band observations from MISTRAL at Observatoire de Haute-Provence
DATE:    23/09/24 19:28:39 GMT
FROM:    Christophe Adami at LAM <christophe.adami@lam.fr>

P. Amram, C. Adami, S. Basa (LAM/PythÃ©as), T. Adami (ENS Paris-Saclay), B. 
Schneider (MIT), A. Saccardi, S. D. Vergani, (GEPI, Obs. de Paris), S. 
Antier, A. de Ugarte Postigo (OCA), E. Le Floc'h, D. GÃ¶tz, F. SchÃ¼ssler, 
D. Turpin (CEA-Saclay), report, on behalf of a larger collaboration:

We observed the field of GRB 230812B (Fermi GBM Team GCN, 34386 and all 
subsequent GCNs) using the MISTRAL spectro-imager of Observatoire de Haute 
Provence (OHP) in imaging mode. We obtained during the 2023 09 22 night 12x600s 
exposure in the r'-band with a mid-epoch of 20:30 UT.

We derive the following photometry, calibrated against the Pan-STARRS catalog, 
not corrected for the underlying galaxy, and not corrected for Galactic dust reddening:

2023 09 22 20:30 UT r' = 22.37 +/- 0.14

We acknowledge the excellent support from Yoann Degot-Longhi (Observatoire de Haute 
Provence) and we thank Isabelle Boisse.


GRB_name: GRB230916A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34779
SUBJECT: transient AT2023sva: A Binary Driven Hypernova with a possible associated supernova
DATE:    23/09/28 16:05:44 GMT
FROM:    Remo Ruffini at ICRA <ruffini@icra.it>

R. Ruffini, Y. Aimuratov, L. Becerra, C.L. Bianco, C. Cherubini, S. Filippi, Liang Li, R. Moradi, F. Rastegar Nia, J.A. Rueda, N. Sahakyan, Y. Wang, S.S. Xue, S.R. Zhang, on behalf of the ICRANet team, report:


Following the BdHN classification [Aimuratov, et al., ApJ 955 (2023) 93] and the determination of the redshift z=2.2 of transient AT2023sva (de Ugarte Postigo, et al., GCN 34740), from the energetics evaluated by Liang Li (2023) from Fermi GBM data in (2.15+/-0.13)x10^{52} erg (see attached figure), we conclude that the source is a BdHN II (GRB230916A).

We Propose to look with the James Webb Space Telescope the appearance of the associated supernova (SN) on October 31 (+/-1 day), in order to extend the GRB-SN connection in the range 1<z<3 and verify the standard candle nature of SNe Ib/c.

Figure: http://www.icranet.org/documents/GRB230916A.pdf


GRB_name: GRB230916B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34780
SUBJECT: AT2023sva / GRB230916B: GIT observations of the afterglow
DATE:    23/09/28 18:27:31 GMT
FROM:    Varun Bhalerao at IIT Bombay <varunb@iitb.ac.in>

A. Salgundi, V. Swain, R. Kumar, G. Waratkar, R. Sharma, V. Bhalerao (IITB), G.C. Anupama, S. Barway (IIA) and K. Angail (IAO) report on behalf of the GIT team:

We observed AT2023sva (Vail et al., GCN 34730; Tonry et al. 2023, TNS report 188327) which is confirmed as an orphan afterglow (Roberts et al., GCN Circ. 34748; GCN Circ. 34749) with the 0.7m GROWTH-India Telescope (GIT). The observations started at 16:42:17 UT on 2023-09-19, roughly 2.3 days after the first ZTF report. We obtained 10 images of 300s exposure in the r' filter. We clearly detect the candidate in our stacked image at the position reported by Vail et al., GCN Circ. 34730. It was not detected in deep observations on later days. The photometry of the candidate is reported below.

----------------------------------------------------------------
| JD (mid)          | Filter | Total Exposure (s) | Magnitude (AB) | Limiting Mag (AB) |
| ----------------- | ------ | ------------------ | -------------- | ----------------- |
| 2460207.214532005 | r'     | 10x300             | 21.89 +/- 0.07 | 22.63             |
| 2460209.289487210 | r'     | 14x300             | --             | 22.28             |
| 2460210.459151377 | r'     | 14x300             | --             | 22.36             |

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

The measurement is calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.

Based on the publicly avialable photometry (Vail et al., GCN Circ. 34730; Malesani et al., GCN Circ. 34731; Parra-Ramos et al., GCN Circ. 34744) and our measurements, we find that the source is consistently fading as a power-law with flux proportional to (tâˆ’t0)^âˆ’alpha where t0 is MJD 60203.08 +/- 0.25 (2023-09-16 01:55:12) and alpha = 3.79 +/- 0.48. This decline is much faster than typical afterglows. This t0 is consistent with Fermi GBM trigger 716527670/230916144, which is also spatially coincident with the afterglow as reported by Roberts et al. (GCN 34748). The t0 fit confirms the association between the two events, which we name GRB 230916B. 

The t0 is not consistent with GRB 230916A (Grefenstette et al., GCN 34721). We note that Ruffini et al (GCN 34779) also are referring to this GRB rather than the NuSTAR-reported trigger.  

Further imaging of the field is encouraged to find any potential host galaxy.

The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.


GRB_name: GRB230930A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34784
SUBJECT: GRB 230930A: Fermi GBM Final Real-time Localization
DATE:    23/09/30 22:11:01 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 22:00:25 UT on 30 Sep 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 230930A (trigger 717804030.135796 / 230930917).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 105.6, Dec = -9.2 (J2000 degrees, equivalent to J2000 07h 02m, -9d 11'), with a statistical uncertainty of 6.8 degrees.

The angle from the Fermi LAT boresight is 70.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230930917/quicklook/glg_skymap_all_bn230930917.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230930917/quicklook/glg_healpix_all_bn230930917.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn230930917/quicklook/glg_lc_medres34_bn230930917.gif


GRB_name: GRB231003A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34793
SUBJECT: GRB 231003A: Fermi GBM Final Real-time Localization
DATE:    23/10/03 21:12:36 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 21:01:59 UT on 3 Oct 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231003A (trigger 718059724.905152 / 231003876).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 300.8, Dec = 71.1 (J2000 degrees, equivalent to J2000 20h 03m, 71d 05'), with a statistical uncertainty of 1.4 degrees.

The angle from the Fermi LAT boresight is 169.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231003876/quicklook/glg_skymap_all_bn231003876.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231003876/quicklook/glg_healpix_all_bn231003876.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231003876/quicklook/glg_lc_medres34_bn231003876.gif


GRB_name: GRB231003A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34794
SUBJECT: GRB 231003A is not a GRB
DATE:    23/10/04 02:17:22 GMT
FROM:    Cori Fletcher at USRA <cfletcher@usra.edu>

C. Fletcher (USRA) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:

"The Fermi Gamma-ray Burst Monitor (GBM) trigger 718059724/231003876 at 21:01:59.91 UT on 03 October 2023, tentatively classified as GRB 231003A (GCN34793), is in fact not due to a GRB. This trigger is likely due to local particles."


GRB_name: GRB231004A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34795
SUBJECT: GRB 231004A: Fermi GBM Final Real-time Localization
DATE:    23/10/04 08:33:54 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 08:23:35 UT on 4 Oct 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231004A (trigger 718100620.108376 / 231004350).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 68.3, Dec = -9.9 (J2000 degrees, equivalent to J2000 04h 33m, -9d 54'), with a statistical uncertainty of 3.4 degrees.

The angle from the Fermi LAT boresight is 94.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231004350/quicklook/glg_skymap_all_bn231004350.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231004350/quicklook/glg_healpix_all_bn231004350.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231004350/quicklook/glg_lc_medres34_bn231004350.gif


GRB_name: GRB231004A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34804
SUBJECT: GRB 231004A: CALET Gamma-Ray Burst Monitor detection
DATE:    23/10/05 18:15:41 GMT
FROM:    Yuta Kawakubo at Louisiana State University <kawakubo1@lsu.edu>

S. Ricciarini (U of Florence), A. Yoshida, T. Sakamoto,
S. Sugita (AGU), Y. Kawakubo (LSU), K. Yamaoka (Nagoya U),
S. Nakahira (JAXA), Y. Asaoka (ICRR), S. Torii, Y. Akaike, 
K. Kobayashi (Waseda U), Y. Shimizu, T. Tamura (Kanagawa U),
N. Cannady (GSFC/UMBC), M. L. Cherry (LSU), P. S. Marrocchesi (U of Siena),
and the CALET collaboration:

The long GRB 231004A (Fermi GBM Final Real-time Localization: Fermi GBM team,
GCN Circ. 34795) triggered the CALET Gamma-ray
Burst Monitor (CGBM) at 08:23:32.70 UTC on 4 October 2023
(http://cgbm.calet.jp/cgbm_trigger/flight/1380443018/).
The burst signal was seen by only the SGM detector.

The burst light curve shows a multi-peaked structure that starts
at T+2.1 sec, peaks at T+2.9 sec, and ends at T+4.1 sec.
The T90 and T50 durations measured by the SGM data are 1.7 +/- 0.2 sec
and 1.1 +/- 0.3 sec (40-1000 keV), respectively.

The ground-processed light curve is available at

http://cgbm.calet.jp/cgbm_trigger/ground/1380443018/index.html

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


GRB_name: GRB231004A
Detection_method: CALET
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34812
SUBJECT: GRB 231004A: Glowbug gamma-ray detection
DATE:    23/10/11 19:55:47 GMT
FROM:    C.C. Cheung at Naval Research Lab <Teddy.Cheung@nrl.navy.mil>

M. Kerr, C.C. Cheung, J. E. Grove, R. Woolf (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge (MSFC), and M.S. Briggs (UAH) report:
 
The Glowbug gamma-ray telescope [1,2], operating on the International Space Station, reports the detection of GRB 231004A, which was also detected by Fermi/GBM and CALET (GCN 34795, 34804).
 
Using an adaptive window with a resolution of 32-ms, the burst onset is determined to be 2023-10-04 08:23:33.360 with a duration of 4.1 s and a total significance of about 29.0 sigma. The light curve comprises a single broad peak.
 
Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission over this duration results in a photon index dN/dE~E^x of x=1.3 and a cutoff energy ("Epeak") of 298 keV. The modeled 10-10000 keV fluence is 2.2e-06 erg/cm^2.
 
The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.
 
Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC.  It was launched on 2023 March 15 aboard the Department of Defense Space Test Programâ€™s STP-H9 to the ISS.  The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.
 
[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006
 
Distribution Statement A: Approved for public release.  Distribution is unlimited.


GRB_name: GRB231012A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34813
SUBJECT: GRB 231012A: Fermi GBM Final Real-time Localization
DATE:    23/10/12 05:42:50 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 05:32:20 UT on 12 Oct 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231012A (trigger 718781545.556372 / 231012231).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 29.6, Dec = 19.7 (J2000 degrees, equivalent to J2000 01h 58m, 19d 41'), with a statistical uncertainty of 4.8 degrees.

The angle from the Fermi LAT boresight is 113.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231012231/quicklook/glg_skymap_all_bn231012231.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231012231/quicklook/glg_healpix_all_bn231012231.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231012231/quicklook/glg_lc_medres34_bn231012231.gif


GRB_name: GRB231012A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34814
SUBJECT: GRB 231012A: Fermi GBM Final Real-time Localization
DATE:    23/10/12 17:05:29 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 16:54:51 UT on 12 Oct 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231012A (trigger 718822496.021004 / 231012705).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 144.5, Dec = 64.7 (J2000 degrees, equivalent to J2000 09h 37m, 64d 42'), with a statistical uncertainty of 10.7 degrees.

The angle from the Fermi LAT boresight is 155.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231012705/quicklook/glg_skymap_all_bn231012705.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231012705/quicklook/glg_healpix_all_bn231012705.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231012705/quicklook/glg_lc_medres34_bn231012705.gif


GRB_name: GRB231012B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34815
SUBJECT: Correction in GCN 34814: GRB 231012B (not GRB 231012A)
DATE:    23/10/12 20:30:28 GMT
FROM:    Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov>

V. Sharma (NASA GSFC/UMBC) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:

"The Fermi Gamma-ray Burst Monitor (GBM) trigger 718822496.021004 / 231012705, which occurred at 16:54:51 UT on 12 Oct 2023, is misnamed as GRB 231012A (GCN 34814). It is in fact the second GRB (refer GCN 34813 for the first GRB 231012A) trigger on the same date and should be a new GRB 231012B. We apologize for any confusion caused."


GRB_name: GRB231017A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34822
SUBJECT: GRB231017A: Fermi GBM Final Localization
DATE:    23/10/17 14:51:29 GMT
FROM:    Joe Mangan at IJCLab <joseph.mangan@ijclab.in2p3.fr>

The Fermi GBM team reports the detection of a likely Long GRB.

At 08:05:03.30 UT on 17 October 2023, the Fermi Gamma-Ray Burst Monitor (GBM) triggered and located GRB231017A (trigger 719222708 / 231017337).

The on-ground calculated location, using the GBM trigger data, is RA = 88.8, DEC = 57.2 (J2000 degrees, equivalent to 5h 55m, 57d 09'), with a statistical uncertainty of 5.7 degrees (radius, 1-sigma containment, statistical only; there is additionally a systematic error which we have characterized as a core-plus-tail model, with 90% of GRBs having a 3.7 deg error and a small tail suffering a larger than 10 deg systematic error. [Connaughton et al. 2015, ApJS, 216, 32] ).

The angle from the Fermi LAT boresight at the GBM trigger time is 58 degrees.

The skymap can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231017337/quicklook/glg_skymap_all_bn231017337.png

The HEALPix FITS file, including the estimated localization systematic, can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231017337/quicklook/glg_healpix_all_bn231017337.fit

The GBM light curve can be found here: https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231017337/quicklook/glg_lc_medres34_bn231017337.gif


GRB_name: GRB231017A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34824
SUBJECT: GRB 231017A: Swift/BAT-GUANO candidate arcminute localization of a burst
DATE:    23/10/17 15:30:08 GMT
FROM:    Jimmy DeLaunay at University of Alabama  <delauj2@gmail.com>

James DeLaunay (U Alabama, PSU), Aaron Tohuvavohu (U Toronto), Gayathri Raman (PSU), Jamie A. Kennea (PSU), Tyler Parsotan (NASA GSFC)  report:

Swift/BAT did not localize GRB 231017A onboard (T0: 2023-10-17T08:05:03.30 UTC, Fermi/GBM GCN 34822, Trigger 719222708).

The Fermi notice, distributed in near real-time, triggered the Swift Mission Operations Center operated Gamma-ray Urgent Archiver for Novel Opportunities (GUANO; Tohuvavohu et al. 2020, ApJ, 900, 1). 

Upon trigger by this notice, GUANO sent a command to the Swift Burst Alert Telescope (BAT) to save 200 seconds of BAT event-mode data from [-50,+150] seconds around the time of the burst. All the requested event mode data was delivered to the ground.

The BAT likelihood search, NITRATES (DeLaunay + Tohuvavohu 2022, ApJ, 941, 169), performed on the temporal window [T0-20 s, T0+20 s], detects the burst with a sqrt(TS) of 15 in a 2.048 s analysis time bin, starting at T0 - 0.512 s. 

A candidate arcminute localization is found with DeltaLLHOut of 17 and a DeltaLLHPeak of 6.

See Section 9.1 and Figures 10 and 17 in the NITRATES paper for brief descriptions and interpretations of sqrt(TS), DeltaLLHPeak, and DeltaLLHOut.

The BAT position is
RA, Dec = 86.191, +56.666 deg which is
   RA(J2000)  = 05 44m 45.84s
   Dec(J2000) = +56d 39â€² 57.6â€³
with an estimated uncertainty of 6 arcmin radius.

XRT and UVOT follow-up has been requested.
Results of follow-up observations will be reported in future circulars.

GUANO is a fully autonomous, extremely low latency, spacecraft
commanding pipeline designed for targeted recovery of BAT event mode
data around the times of compelling astrophysical events to enable
more sensitive GRB searches.

A live reporting of Swift/BAT event data recovered by GUANO can be
found at: https://www.swift.psu.edu/guano/


GRB_name: GRB231017A
Detection_method: Swift Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34825
SUBJECT: GRB 231017A: Swift ToO observations
DATE:    23/10/17 17:27:04 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

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

Swift has initiated a ToO observation of the Swift/BAT-GUANO GRB 231017A. 
Automated analysis of the XRT data will be presented online at
https://www.swift.ac.uk/ToO_GRBs/00021623

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

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

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


GRB_name: GRB231018A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34826
SUBJECT: GRB 231018A: Fermi GBM Final Real-time Localization
DATE:    23/10/18 12:40:39 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 LONG GRB

At 12:30:10 UT on 18 Oct 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231018A (trigger 719325015.663762 / 231018521).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 3.0, Dec = 50.7 (J2000 degrees, equivalent to J2000 00h 12m, 50d 42'), with a statistical uncertainty of 1.0 degrees.

The angle from the Fermi LAT boresight is 131.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231018521/quicklook/glg_skymap_all_bn231018521.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231018521/quicklook/glg_healpix_all_bn231018521.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231018521/quicklook/glg_lc_medres34_bn231018521.gif


GRB_name: GRB231018A
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34827
SUBJECT: GRB 231018A: BALROG localization (Fermi Trigger  / GRB 231018521)
DATE:    23/10/18 13:15:13 GMT
FROM:    Jochen Greiner at MPE <jcgrog@mpe.mpg.de>

T. Preis, B. Biltzinger, J. Burgess & J. Greiner (all MPE Garching) report:

The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
 at 12:30:10 on 18 Oct. 2023 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) = 1.2+/-0.5 deg
Decl.(2000.0) = 51.5+/-0.2 deg
We estimate an additional systematic error of 1 deg.

Further details are available at:
https://grb.mpe.mpg.de/grb/GRB231018521/

The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB231018521/healpix

The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB231018521/json

                        


GRB_name: GRB231012B
Detection_method: Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34828
SUBJECT: GRB 231012B may not be a GRB
DATE:    23/10/18 14:37:59 GMT
FROM:    Vidushi Sharma at NASA GSFC/UMBC <vidushi.sharma@nasa.gov>

V. Sharma (NASA GSFC/UMBC) reports on behalf of the Fermi Gamma-ray Burst Monitor Team:

The Fermi Gamma-ray Burst Monitor (GBM) trigger 718822496/231012705, which occurred at 16:54:51 UT on 12 October 2023, was tentatively classified as GRB 231012B (GCN 34815). However, we are uncertain about its classification as a GRB and can likely be due to distant particles.


GRB_name: GRB231017A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34829
SUBJECT: GRB 231017A: Swift-XRT observations
DATE:    23/10/18 15:56:18 GMT
FROM:    Phil Evans at U of Leicester <pae9@star.le.ac.uk>

S. Dichiara (PSU), J.A. Kennea (PSU), J.P. Osborne (U. Leicester), K.L.
Page (U. Leicester), A.P. Beardmore (U. Leicester), E. Ambrosi 
(INAF-IASFPA) , M. Capalbi (INAF-IASFPA), M. Perri (SSDC & INAF-OAR),
A. Tohuvavohu (U. Toronto) and P.A. Evans (U. Leicester) reports on
behalf of the Swift-XRT team:

Swift-XRT has performed follow-up observations of the
Swift/BAT-GUANO-detected burst GRB 231017A (GCN Circ. 34824, DeLaunay
et al.), collecting 4.2 ks of Photon Counting (PC) mode data between
T0+32.7 ks and T0+101.7 ks. 

One uncatalogued X-ray source has been detected consistent with being
within 493 arcsec of the Swift/BAT-GUANO position, it is below the RASS
limit and shows no definitive signs of fading. Therefore, at the
present time we cannot confirm this as the afterglow. Details of this
source are given below:

Source 2:
  RA (J2000):  86.1666  =  05:44:39.99
  Dec (J2000): +56.7487  =  +56:44:55.3
  Error: 8.4 arcsec (radius, 90% conf.)
  Count-rate: (2.09 [+1.11, -0.84])e-3 ct s^-1  
  Distance: 301 arcsec from Swift/BAT-GUANO position.
  Flux: (3.3 [+1.8, -1.3])e-14 erg cm^-2 s^-1 (observed, 0.3-10 keV)

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

The results of the XRT-team automatic analysis of the XRT observations,
including a position-specific upper limit calculator, are available at
https://www.swift.ac.uk/ToO_GRBs/00021623.

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


GRB_name: GRB231017A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34830
SUBJECT: GRB 231017A: Fermi GBM Detection
DATE:    23/10/18 16:19:02 GMT
FROM:    Joe Mangan at IJCLab <joseph.mangan@ijclab.in2p3.fr>

J.Mangan (CNRS/IJCLab), E. Bissaldi (Politecnico and INFN Bari) and C. Meegan (UAH) report on behalf of the Fermi Gamma-ray Burst Monitor Team:

"At 08:05:03.30 UT on 17 October 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 231017A (trigger 719222708/231017337), which was also 
detected by the Swift/BAT-GUANO (DeLaunay et al. 2023, GCN 34824). 

The Fermi GBM Final Real-time Localization is reported in GCN 34822.

The GBM light curve consists of a single emission episode with a duration (T90)
of about 4.8 s (50-300 keV). The time-averaged spectrum
from T0-3.5 to T0+4.7 s is best fit by
a power law function with an exponential high-energy cutoff.
The power law index is -1.1 +/- 0.2 and the cutoff energy,
parameterized as Epeak, is 270 +/- 82 keV.

A Band function fits the spectrum equally well
with Epeak= 175 +/- 92 keV, alpha = -0.9 +/- 0.3 and beta = -1.9 +/- 0.3.

The event fluence (10-1000 keV) in this time interval is
(1.7 +/- 0.2)E-06 erg/cm^2. The 64-msec peak photon flux measured
starting from T0+0.77 s in the 10-1000 keV band is 7.8 +/- 1.6 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: GRB231018A
Detection_method: Fermi GBM Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34831
SUBJECT: GRB 231018A: Fermi GBM Detection
DATE:    23/10/18 17:36:50 GMT
FROM:    Stephen Lesage at Fermi-GBM Team <sjl0014@uah.edu>

S. Lesage (UAH), E. Bissaldi (Politecnico and INFN Bari) and C. Meegan (UAH)
report on behalf of the Fermi Gamma-ray Burst Monitor Team:

"At 12:30:10 UT on 18 October 2023, the Fermi Gamma-ray Burst Monitor (GBM)
triggered and located GRB 231018A (trigger 719325015/231018521).
The Fermi GBM Final Real-time Localization is reported in GCN 34826.

The angle from the Fermi LAT boresight is 131 degrees.

The GBM light curve consists of multiple multiple pulses with a duration (T90)
of about 39.4 s (50-300 keV). The time-averaged spectrum
from T0-4.6 to T0+92.7 s is best fit by
a Band function with Epeak = 109 +/- 3 keV,
alpha = -1.24 +/- 0.02, and beta = -2.56 +/- 0.05.

The event fluence (10-1000 keV) in this time interval is
(1.192 +/- 0.009)E-04 erg/cm^2. The 1-sec peak photon flux measured
starting from T0+57 s in the 10-1000 keV band is 75 +/- 1 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: GRB231015A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34832
SUBJECT: GRB 231015A: AstroSat CZTI detection
DATE:    23/10/18 17:40:44 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

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

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 231015A which was also detected by Konus-Wind (reported in IPN_RAW GCN notices).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2023-10-15 23:49:53.50 UTC. The measured peak count rate associated with the burst is 477 (+43, -43) counts/s above the background in the combined data of two quadrants (out of four), with a total of 5641 (+323, -329) counts. The local mean background count rate was 239 (+3, -3) counts/s. Using cumulative rates, we measure a T90 of 24 (+1, -1) s. 

The source 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 2023-10-15 23:49:53.42 UTC. The measured peak count rate associated with the burst is 864 (+76, -87) counts/s above the background in the combined data of all quadrants, with a total of 10039 (+610, -910) counts. The local mean background count rate was 1514 (+7, -6) counts/s. We measure a T90 of 25 (+4, -2) s from the cumulative Veto light curve.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb


GRB_name: GRB231017A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34833
SUBJECT: GRB231017A: GROWTH-India upper limits on the optical afterglow
DATE:    23/10/18 20:23:19 GMT
FROM:    Anirudh Salgundi <salgundi.anirudh@gmail.com>

R. Kumar, A. Salgundi, R. Sharma, Y. Wagh, V. Swain, V. Bhalerao (IIT Bombay), S. Barway, G. C. Anupama (IIA), K. Angail (IAO)

We observed the field of GRB 231017A detected by Fermi (Fermi GBM team GCN 34822) with 0.7m GROWTH-India Telescope (GIT). GIT was triggered at 2023-10-18 15:49:46.29 UT, i.e., 1.32 days after the Fermi trigger, as a response to the Swift/GUANO trigger (J DeLaunay et al., GCN 34824). We obtained multiple frames in the g' and r' bands, covering the localisation reported by Swift/XRT (P. A. Evans et al., GCN 34825). We searched individual images and the stacked image for an afterglow, but do not detect any. Our upper limits on the magnitude of the afterglow are:

JD (mid) | t_mid-t0 (days)| Filter | Exposure (s) | Limiting Magnitude (5 sigma) |

2460236.187750 | 1.351 | g' | 3 x 300 | 19.27 |
2460236.171885 | 1.335 | r' | 6 x 300 | 21.08 |
2460236.250104 | 1.413 | g' | 2 x 400 | 19.98 |

The magnitudes are calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.

The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.


GRB_name: GRB231017A
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34834
SUBJECT: GRB 231017A: LCOGT Optical Upper Limits
DATE:    23/10/18 20:47:26 GMT
FROM:    Robert Strausbaugh at Eastern Illinois University <rstrausbaugh@eiu.edu>

R. Strausbaugh (Eastern Illinois University), A. Cucchiara (NASA) report on behalf of a larger collaboration:

We observed the Fermi GRB 231017A field (Fermi GBM team, GCN 34822) with the LCOGT 1-meter Sinistro instrument at the Teide Observatory, Tenerife site, on October 18, from 01:01 to 01:34 UT (corresponding to 15.93 to 16.48 hours from the GRB trigger time) with the SDSS r and i filters.

We performed a series of 3x300s exposures in each band.  We do not detect a source within the Swift-XRT error region around the candidate X-ray source (Dichiara et al., GCN 34829) in either band.

The following upper limits are calculated using the PanSTARRS catalog as reference:

r > 23.0
i > 22.6

These magnitudes are not corrected for galactic extinction.


GRB_name: GRB231015A
Detection_method: AstroSat CZTI
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34835
SUBJECT: GRB 231015A: Glowbug gamma-ray detection
DATE:    23/10/18 22:27:07 GMT
FROM:    C.C. Cheung at Naval Research Lab <Teddy.Cheung@nrl.navy.mil>

M. Kerr, C.C. Cheung, J. E. Grove, R. Woolf (NRL), A. Goldstein (USRA), C.A. Wilson-Hodge (MSFC), and M.S. Briggs (UAH) report:

The Glowbug gamma-ray telescope [1,2], operating on the International Space Station, reports the detection of GRB 231015A, which was also detected by AstroSat and Konus-Wind (GCN 34832). AstroSat CZTI detected multiple peaks of emission with the strongest peak at 2023-10-15 23:49:53.50 UTC.

Using an adaptive window with a resolution of 32-ms, the onset for the multi-peaked emission reported by AstroSat is determined to be 2023-10-15 23:49:21.128 with a duration of 36.9 s and a total significance of about 95.4 sigma. The light curve comprises two primary peaks separated by about 15 s.

Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission over this duration results in a photon index dN/dE~E^x of x=0.1 and a cutoff energy ("Epeak") of 292 keV.  The modeled 10-10000 keV fluence is 3.4e-05 erg/cm^2.

Additional analysis of Glowbug data revealed an earlier component to the two main emission peaks. Using an adaptive window with a resolution of 32-ms, the burst onset of this earlier emission is determined to be 2023-10-15 23:47:03.912 with a duration of 10.3 s and a total significance of about 13.4 sigma.  The light curve comprises a single broad peak.

Using a standard power-law function with an exponential high-energy cutoff [3] to model the emission in the earlier component over this duration results in a photon index dN/dE~E^x of x=2.0 and a cutoff energy ("Epeak") of 193 keV.  The modeled 10-10000 keV fluence is 8.9e-07 erg/cm^2.

The analysis results presented here are preliminary and use a response function that lacks a detailed characterization of the surrounding passive structure of the ISS.

Glowbug is a NASA-funded technology demonstrator for sensitive, low-cost gamma-ray transient telescopes developed, built, and operated by the U.S. Naval Research Laboratory (NRL) with support from the University of Alabama in Huntsville, USRA, and NASA MSFC.  It was launched on 2023 March 15 aboard the Department of Defense Space Test Programâ€™s STP-H9 to the ISS.  The detector comprises 12 large-area (15 cm x 15 cm) CsI:Tl panels covering the surface of a half cube, and two hexagonal (5-cm diameter, 10-cm length) CLLB scintillators, giving it a large field of view (instantaneous FoV ~2/3 sky) over a wide energy band of 50 keV to >2 MeV.

[1] Grove, J.E. et al. 2020, Proc. Yamada Conf. LXXI, arXiv:2009.11959
[2] Woolf, R.S. et al. 2022, Proc. SPIE, 12181, id. 121811O
[3] Goldstein, A. et al. 2020, ApJ 895, 40, arXiv :1909.03006


GRB_name: GRB231017A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34836
SUBJECT: GRB 231017A: Las Cumbres optical upper limit 
DATE:    23/10/18 23:23:48 GMT
FROM:    Manisha Shrestha at University of Arizona <mshrestha1@arizona.edu>

M. Shrestha (Univ. of Arizona),  D. Sand (Univ. of Arizona), K. D. Alexander (Univ. of Arizona), J. Andrews (Gemini), J. Pearson (Univ. of Arizona), N. Smith (Univ. of Arizona), K. Bostroem (Univ. of Arizona) D. A. Howell (LCO/UCSB), C. McCully (LCO/UCSB), M. Newsome (LCO/UCSB), E Padilla Gonzalez (LCO/UCSB), C. Pellegrino (LCO/UCSB), G. Terreran (LCO/UCSB), J. Farah (LCO/UCSB) report on behalf of a wider Global Supernova Project collaboration:
 
We observed the field of GRB 231017A (Fermi GBM team GCN 34822, Trigger 719222708) localized by Swift/BAT-GUANO (DeLaunay et al. GCN 34824) with the 1-m telescope, on 2023-10-18T02:56:38.021 UT (60235.12 MJD, ~0.8 days after the trigger) using the Sinistro instrument in V, g, r, i bands. We do not detect any new optical counterpart within the error region of BAT-GUANO with upper limit of:

g> 22.5
r> 21.2
i> 20.9

These values were calculated with respect to ATLAS-REFCAT2 (Tonry et al. 2018, ApJ 867 105) catalog are not corrected for galactic extinction. This non-detection is in agreement with Strausbaugh et al., GCN 34834 and Kumar et al., GCN 34833.


GRB_name: GRB231018A
Detection_method: Fermi GBM Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34839
SUBJECT: GRB 231018A: GROWTH-India Follow-Up of a Fermi Long GRB
DATE:    23/10/19 07:33:47 GMT
FROM:    Varun Bhalerao at IIT Bombay <varunb@iitb.ac.in>

R. Kumar, Y. Wagh, R. Sharma, A. Salgundi, V. Swain, D. Raman, T. Roychowdhury, V. Bhalerao (IIT Bombay), S. Barway, G. C. Anupama (IIA), K. Angail (IAO)

We observed the field of GRB 231018A detected by Fermi (Fermi GBM Team, GCN Circ. 34826; GCN Circ. 34831) with 0.7m GROWTH-India Telescope (GIT). GIT started observing the field at 2023-10-18 17:28:08.912 UT, i.e., 4.96 hours after the Fermi trigger. We obtained a series of 25 r' band images each of 300s exposure, covering 9.44 square degrees. This corresponds to 21.7% of the probability enclosed in the Fermi GBM Final Real-time Localisation (Fermi GBM Team, GCN Circ. 34826) and 20.17% of the probability enclosed in the BALROG localization (Preis et al., GCN Circ. 34827). Where available, PanSTARRS images (Chambers et al., 2016) were used as references for image subtraction. In other fields, we looked for new point sources absent in the GSC2.3 catalog. We did not find any suitable afterglow candidate, reaching a median limiting magnitude of 18.95 in the r' band. The detailed observing log is:

| Tile ID | RA (deg) | Dec (deg) | Lim Mag (AB) | Method |

| 54910 | 0.12 | 50.1 | 18.54 | Catalog     |
| 55565 | 1.25 | 51.5 | 18.93 | Subtraction |
| 55567 | 3.51 | 51.5 | 18.96 | Subtraction |
| 55883 | 0.13 | 51.5 | 18.82 | Catalog     |
| 54579 | 3.36 | 49.4 | 18.66 | Subtraction |
| 55238 | 0.12 | 50.1 | 18.25 | Catalog     |
| 54912 | 2.32 | 50.1 | 19.02 | Subtraction |
| 55241 | 2.35 | 50.8 | 19.01 | Subtraction |
| 55564 | 0.13 | 51.5 | 18.74 | Catalog     |
| 55242 | 3.46 | 50.8 | 18.96 | Subtraction |
| 55240 | 1.24 | 50.8 | 19.02 | Subtraction |
| 55243 | 4.57 | 50.8 | 18.98 | Subtraction |
| 54577 | 1.20 | 49.4 | 18.22 | Subtraction |
| 54914 | 4.51 | 50.1 | 17.48 | Subtraction |
| 54578 | 2.28 | 49.4 | 18.76 | Subtraction |
| 56201 | 2.45 | 52.9 | 15.70 | Subtraction |
| 55885 | 1.27 | 52.2 | 18.97 | Subtraction |
| 55887 | 3.56 | 52.2 | 19.03 | Subtraction |
| 55568 | 4.64 | 51.5 | 18.85 | Subtraction |
| 55886 | 2.42 | 52.2 | 18.97 | Subtraction |
| 54913 | 3.42 | 50.1 | 19.05 | Subtraction |
| 55563 | 0.13 | 50.8 | 18.64 | Catalog     |
| 54911 | 1.22 | 50.1 | 19.12 | Subtraction |

The magnitudes are calibrated against PanSTARRS DR1 (Chambers et al., 2016) and not corrected for Galactic extinction.

The GROWTH India Telescope (GIT; Kumar et al. 2022) is a 70-cm telescope with a 0.7-degree field of view, set up by the Indian Institute of Astrophysics (IIA) and the Indian Institute of Technology Bombay (IITB) with funding from DST-SERB and IUSSTF. It is located at the Indian Astronomical Observatory (Hanle), operated by IIA. We acknowledge funding by the IITB alumni batch of 1994, which partially supports the operations of the telescope. Telescope technical details are available at https://sites.google.com/view/growthindia/.


GRB_name: GRB231017A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34840
SUBJECT: GRB 231017A: JinShan optical upper limit
DATE:    23/10/19 13:18:13 GMT
FROM:    Dong Xu at NAOC/CAS <dxu@nao.cas.cn>

D. Xu, X. Liu, S.Q. Jiang, Z.P. Zhu, S.Y. Fu, J. An, T.H. Lu (NAOC), J.Z. Liu (XAO) report on behalf of a large collaboration:

We observed the field of GRB 231017A detected by Fermi/GBM (Fermi GBM team, GCN 34822) and Swift/BAT-GUANO (DeLaunay et al. GCN 34824) using the No.2 50cm telescope (50B) located at Altay, Xinjiang, China. We obtained 20x180 s frames in the Sloan r-band, starting at 15:41:21 UT on 2023-10-17, i.e. 7.6 hr after the trigger.

No optical transient is detected in our stacked image within the error region of the Swift/BAT-GUANO, with the Swift-XRT Source 2 candidate inside the error region (Dichiara et al. GCN 34829), down to a limiting magnitude of r>20.5, calibrated with the nearby PanSTARRS field.

Altay Astronomical Time-Domain Project (JinShan Project for short) is located on the southern side of the Altay mountains in Xinjiang, China. It has geographical Longitude 88 43 35 E, Latitude +47 35 24 N, and Altitude 1025 meters. Altay and JinShan have the same meaning of Gold Mountain. The project consists of four 50cm telescopes with FOV of 1.7x1.7 deg^2 for each (50A, 50B, 50C, and 50D), two 100cm telescopes with FOV of 1.4x1.4 deg^2 for each (100A and 100B), and one 100cm telescope with FOV of 14x14 arcmin^2 (100C). Each telescope has different filters. JinShan is now at its early commissioning stage.


GRB_name: GRB231017A
Detection_method: Optical
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34841
SUBJECT: GRB 231017A: GOTO optical upper limits
DATE:    23/10/19 16:24:59 GMT
FROM:    Ben Gompertz at U of Birmingham <b.gompertz@bham.ac.uk>

S. Belkin; K. Ackley; A. Kumar; B. P. Gompertz; B. Godson; R. Starling; M. J. Dyer; J. Lyman; K. Ulaczyk; F. Jimenez-Ibarra; D. O'Neill; D. Steeghs; D. K. Galloway; V. Dhillon; P. O'Brien; G. Ramsay; K. Noysena; R. Kotak; R. P. Breton; L. K. Nuttall; E. Pall'e and D. Pollacco report on behalf of the GOTO collaboration:

We report on observations with the Gravitational-wave Optical Transient Observer (GOTO; Steeghs et al. 2022) in response to GRB 231017A (Fermi GBM team, GCN 34822). Targeted observations were performed between 00:20:50 UT on 2023-10-18 and 02:37:04 UT on 2023-10-18 (starting ~16.25 hours after trigger). Each observation consisted of 4x90s exposures in the GOTO L-band (400-700 nm).

We identify no candidate optical counterparts within the Swift/BAT-GUANO localisation region (DeLaunay et al., GCN 34824) or at the positions of the 9 sources identified in XRT pointed observations (Evans et al., GCN 34825; Dichiara et al., GCN 34829). The mean 5-sigma limiting magnitude was L > 20.2 mag. This result is consistent with other observations (â€‹â€‹Kumar et al., GCN 34833; Strausbaugh et al., GCN 34834; Shrestha et al., GCN 34836; Xu et al., GCN 34840).

Magnitudes were calibrated using ATLAS-REFCAT2 (Tonry et al. 2018) and are not corrected for Galactic extinction.
GOTO (https://goto-observatory.org<https://goto-observatory.org/>) is a network of telescopes that is principally funded by the STFC and operated at the Roque de los Muchachos Observatory on La Palma, Spain, and Siding Spring Observatory in NSW, Australia, on behalf of a consortium including the University of Warwick, Monash University, Armagh Observatory & Planetarium, the University of Leicester, the University of Sheffield, the National Astronomical Research Institute of Thailand (NARIT), the University of Turku, the University of Portsmouth, the University of Manchester and the Instituto de Astrofisica de Canarias (IAC).


GRB_name: GRB231019A
Detection_method: Fermi GBM final loc
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34842
SUBJECT: GRB 231019A: Fermi GBM Final Real-time Localization
DATE:    23/10/19 17:20:27 GMT
FROM:    Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>

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

At 17:09:58 UT on 19 Oct 2023, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 231019A (trigger 719428203.333452 / 231019715).

The on-ground calculated location, using the Fermi GBM trigger data, is RA = 343.1, Dec = 45.7 (J2000 degrees, equivalent to J2000 22h 52m, 45d 42'), with a statistical uncertainty of 7.2 degrees.

The angle from the Fermi LAT boresight is 92.0 degrees.

The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231019715/quicklook/glg_skymap_all_bn231019715.png

The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231019715/quicklook/glg_healpix_all_bn231019715.fit

The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2023/bn231019715/quicklook/glg_lc_medres34_bn231019715.gif


GRB_name: GRB230911C
Detection_method: Swift-XRT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34843
SUBJECT: GRB 230911C: ATCA detection of possible radio counterpart
DATE:    23/10/19 17:29:14 GMT
FROM:    Sarah Chastain at University of New Mexico <sarahichastain@gmail.com>

S. Chastain (UNM),  G. E. Anderson (Curtin), J. K. Leung (UofT/HUJI), S. D. Ryder (Macquarie), A. J. van der Horst (GWU), A. Gulati (USyd), and L. Rhodes (Oxford) on behalf of the ATCA PanRadio GRB collaboration

The Australia Telescope Compact Array (ATCA) observed long GRB 230911C (E. Sonbas et al., GCN 34655) as part of the ATCA "PanRadio GRB" Large Project C3542 (PI: G. Anderson) on 2023-09-11 UT, 2023-09-13 UT, 2023-09-26 UT, and 2023-10-16 UT.

We detect a possible radio afterglow at 9 GHz in the second epoch, which continues to brighten in the third, and fourth epoch. At 5.5 GHz this source is not detected in any of the observations.
In the fourth epoch at 5.5 GHz, we find 3-sigma upper limit of 105 microJy/beam. In the fourth epoch at 9.0 GHz, the source detected in the previous observations is detected at 150 +/- 35 microJy/beam.
The fitted position is:
RAJ2000  = 15:07:13 +/- 8 arcseconds
DECJ2000 = -41:19:51 +/- 1 arcsecond
This is approximately 18 arcseconds away from the reported Swift/XRT enhanced position (P. A. Evans et al., GCN 34658).

 

Further observations are planned.

We thank the CSIRO Space and Astronomy staff for supporting these observations.
We acknowledge the Gomeroi people as the traditional owners of the Observatory site. The Australia Telescope Compact Array is part of the Australia Telescope National Facility (https://ror.org/05qajvd42) which is funded by the Australian Government for operation as a National Facility managed by CSIRO.


GRB_name: GRB231017A
Detection_method: Swift-UVOT Other
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34844
SUBJECT: GRB 231017A: Swift/UVOT Upper Limit
DATE:    23/10/19 18:34:36 GMT
FROM:    Alice Breeveld at MSSL-UCL <a.breeveld@ucl.ac.uk>

A. A. Breeveld (UCL-MSSL) and T. Parsotan (GSFC/UMBC) report on behalf of the Swift/UVOT team:

The Swift/UVOT began settled observations of the field of GRB 231017A 73640 s after the GBM trigger (Mangan et al., GCN Circ. 34822).
No new sources are seen in the UVOT data.
A preliminary 3-sigma upper limit using the UVOT photometric system, (Breeveld et al. 2011, AIP Conf. Proc. 1358, 373) at the position of the XRT candidate (Source 2) given by Dichiara et al. (GCN Circ. 34829) is:

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

u                73640       101690        4839          >21.0

The magnitude in the table is not corrected for the Galactic extinction due to the reddening of E(B-V) = 0.252 in the direction of the burst (Schlegel et al. 1998).


GRB_name: GRB231018A
Detection_method: IPN Triangulation
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34845
SUBJECT: IPN triangulation of GRB 231018A
DATE:    23/10/19 18:41:19 GMT
FROM:    Dmitry Svinkin at Ioffe Institute <svinkin@mail.ioffe.ru>

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

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

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,
report:

The bright, long-duration GRB 231018A
(Fermi-GBM detection: The Fermi GBM team, GCN Circ. 34826;
BALROG localization: Preis et al., GCN Circ. 34827)
has been detected by Fermi (GBM trigger 719325015), CALET (GBM),
GECAM-B, INTEGRAL (SPI-ACS), Konus-Wind, and Swift (BAT),
so far, at about 45010 s UT (12:30:10).
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:
    1.122 (00h 04m 29s) +47.410 (+47d 24' 36")
 Corners:
    6.422 (00h 25m 41s) +50.650 (+50d 39' 01")
  356.061 (23h 44m 15s) +43.842 (+43d 50' 31")
  357.865 (23h 51m 28s) +44.479 (+44d 28' 43")
   10.820 (00h 43m 17s) +51.565 (+51d 33' 55")
 ---------------------------------------------
The error box area is 6.6 sq. deg, and its maximum
dimension is 12.54 deg (the minimum one is 38 arcmin).
The Sun distance was 137 deg.

The IPN localization is consistent with, but reduces the area of,
the final Fermi-GBM and the BALROG localizations.

This localization may be improved.

A triangulation map and HEALPix FITS files are posted at
http://www.ioffe.ru/LEA/GRBs/GRB231018_T45043/IPN

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


GRB_name: GRB231018A
Detection_method: Konus-Wind Det
Circular_text:
TITLE:   GCN CIRCULAR
NUMBER:  34846
SUBJECT: Konus-Wind detection of GRB 231018A
DATE:    23/10/19 18:44:04 GMT
FROM:    Dmitry Frederiks at Ioffe Institute <fred@mail.ioffe.ru>

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

The long, bright GRB 231018A (Fermi GBM detection: Lesage et al., GCN 34831;
IPN triangulation: Svinkin et al., GCN 34845)
triggered Konus-Wind (KW) at T0=45043.083 s UT (12:30:43.083).

The burst light curve shows a multi-peaked emission complex,
which starts at ~T0-32 s, peaks at ~T0+28 s,
and has a total duration of ~90 s.
The emission is seen up to ~10 MeV.

The Konus-Wind light curve of this GRB is available at
http://www.ioffe.ru/LEA/GRBs/GRB231018_T45043/

As observed by Konus-Wind, the burst had
a fluence of (1.17 Â± 0.04)x10^-4 erg/cm^2 and
a 64-ms peak energy flux, measured from T0 + 28.352 s,
of (2.44 Â± 0.10)x10^-5 erg/cm^2/s (both in the 20 keV - 10 MeV energy range).

The time-integrated spectrum (measured from T0 to T0+38.912 s)
is best fit in the 20 keV - 15 MeV range
by a GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -1.34 (-0.05,+0.05),
the high energy photon index beta = -2.92 (-0.17,+0.12),
the peak energy Ep = 114 (-4,+4) keV,
chi2 = 90/96 dof.

The spectrum near the peak count rate (measured from T0+24.576 to T0+29.696 s)
is best fit in the 20 keV - 15 MeV range
by a GRB (Band) function with the following model parameters:
the low-energy photon index alpha = -1.19 (-0.05,+0.06),
the high energy photon index beta = -3.15 (-0.37,+0.24),
the peak energy Ep = 146 (-7,+8) keV,
chi2 = 67/73 dof.

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


