GRB 250910B
GCN Circular 41808
Subject
GRB 250910B: SVOM/GRM observation
Date
2025-09-12T04:13:28Z (16 hours ago)
From
Chenwei Wang at IHEP <cwwang@ihep.ac.cn>
Via
Web form
SVOM/GRM team: Chen-Wei Wang, Yue Huang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Jean-Luc Atteia (IRAP)
Report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by a burst GRB 250910B (SVOM trigger reference: sb25091008) at 2025-09-10T18:52:06.000 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM team, GCN #41778).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a single pulse with a T90 of 10.0 +4.5/-1.5 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb250910B.png
In addition, the position of this burst, as determined by Fermi/GBM (RA = 80.2, Dec = -46.4, GCN #41778), is located at about 54 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view. ECLAIRs was not collecting data at the time of this burst.
With the localization from Fermi/GBM, the time-averaged spectrum from T0-3 to T0+8.5 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -0.75 +0.12/-0.11 and the cutoff energy, parameterized as Epeak, is 218 +29/-22 keV. The event fluence (10-1000 keV) in this time interval is (5.77 +0.38/-0.36)E-06 erg/cm^2.
The 'Amati' relation diagram of GRB 250910B is shown at:
https://www.bursthub.cn//admin/static/svgrb250910B_amati.png
The Space Variable Objects Monitor (SVOM) is a China-France joint mission led by the Chinese National Space Administration (CNSA, China), National Center for Space Studies (CNES, France) and the Chinese Academy of Sciences (CAS, China), which is dedicated to observing gamma-ray bursts and other transient phenomena in the energetic universe. GRM is developed by the Institute of High Energy Physics (IHEP) of CAS.
The SVOM point of contact for this burst is: Chen-Wei Wang (IHEP)(cwwang@ihep.ac.cn)
GCN Circular 41791
Subject
Fermi GRB 250910B: Global MASTER-Net observations report
Date
2025-09-11T10:31:00Z (a day ago)
From
Vladimir Lipunov at Moscow State U/Krylov Obs <lipunov@xray.sai.msu.ru>
Via
email
V.Lipunov, E.Gorbovskoy, A.Kuznetsov, K.Zhirkov, I.Panchenko, N.Tiurina, P.Balanutsa, V.Topolev, D.Vlasenko,
G.Antipov, A.Sankovich, Yu.Tselik, Ya.Kechin, V.Senik, A.Chasovnikov, K.Labsina, I. Gorbunov (Lomonosov MSU),
O.Gress, N.Budnev (ISU),
C.Francile, F. Podesta, R.Podesta, E. Gonzalez (Observatorio Astronomico Felix Aguilar (OAFA),
A. Tlatov, D. Dormidontov (Kislovodsk Solar Station of the Pulkovo Observatory),
A.Sosnovskij (CrAO),
A. Gabovich, V.Yurkov (Blagoveschensk Educational StateUniversity),
D.Buckley (SAAO),
R.Rebolo (The Instituto de Astrofisica de Canarias),
L.Carrasco, J.R.Valdes, V.Chavushyan, V.M.Patino Alvarez, J.Martinez,
A.R.Corella, L.H.Rodriguez (INAOE, Guillermo Haro Astrophysics Observatory)
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 250910B ( Fermi GBM team, GCN 41778) errorbox 45057 sec after notice time and 45097 sec after trigger time at 2025-09-11 07:23:42 UT, with upper limit up to 19.9 mag. The observations began at zenith distance = 40 deg. The sun altitude is -41.7 deg.
The galactic latitude b = -34 deg., longitude l = 252 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2989479
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
45128 | 2025-09-11 07:23:42 | MASTER-OAFA | (05h 21m 01.46s , -46d 16m 04.7s) | C | 60 | 19.9 |
45203 | 2025-09-11 07:24:58 | MASTER-OAFA | (05h 21m 06.25s , -46d 17m 02.2s) | C | 60 | 19.8 |
45277 | 2025-09-11 07:26:12 | MASTER-OAFA | (05h 21m 01.18s , -46d 17m 59.3s) | C | 60 | 19.9 |
45353 | 2025-09-11 07:27:28 | MASTER-OAFA | (05h 21m 05.78s , -46d 17m 54.0s) | C | 60 | 19.9 |
45428 | 2025-09-11 07:28:43 | MASTER-OAFA | (05h 21m 03.82s , -46d 16m 02.0s) | C | 60 | 19.8 |
45503 | 2025-09-11 07:29:58 | MASTER-OAFA | (05h 21m 03.84s , -46d 17m 30.1s) | C | 60 | 19.8 |
45579 | 2025-09-11 07:31:13 | MASTER-OAFA | (05h 21m 06.46s , -46d 16m 12.8s) | C | 60 | 19.8 |
45656 | 2025-09-11 07:32:31 | MASTER-OAFA | (05h 21m 00.95s , -46d 16m 45.4s) | C | 60 | 19.8 |
45734 | 2025-09-11 07:33:49 | MASTER-OAFA | (05h 21m 01.87s , -46d 15m 42.5s) | C | 60 | 19.8 |
45811 | 2025-09-11 07:35:06 | MASTER-OAFA | (05h 21m 07.33s , -46d 16m 40.1s) | C | 60 | 19.9 |
45888 | 2025-09-11 07:36:22 | MASTER-OAFA | (05h 21m 00.65s , -46d 17m 37.5s) | C | 60 | 19.8 |
45962 | 2025-09-11 07:37:36 | MASTER-OAFA | (05h 21m 07.79s , -46d 17m 14.3s) | C | 60 | 19.9 |
46036 | 2025-09-11 07:38:51 | MASTER-OAFA | (05h 21m 04.04s , -46d 15m 34.4s) | C | 60 | 19.9 |
46112 | 2025-09-11 07:40:06 | MASTER-OAFA | (05h 21m 04.05s , -46d 17m 27.2s) | C | 60 | 19.9 |
46187 | 2025-09-11 07:41:21 | MASTER-OAFA | (05h 21m 07.22s , -46d 15m 29.4s) | C | 60 | 19.9 |
46263 | 2025-09-11 07:42:38 | MASTER-OAFA | (05h 21m 00.93s , -46d 16m 25.0s) | C | 60 | 19.9 |
46340 | 2025-09-11 07:43:55 | MASTER-OAFA | (05h 21m 00.54s , -46d 15m 22.3s) | C | 60 | 19.9 |
46417 | 2025-09-11 07:45:11 | MASTER-OAFA | (05h 21m 06.25s , -46d 16m 20.5s) | C | 60 | 19.8 |
46495 | 2025-09-11 07:46:29 | MASTER-OAFA | (05h 21m 01.68s , -46d 17m 18.0s) | C | 60 | 19.9 |
46569 | 2025-09-11 07:47:43 | MASTER-OAFA | (05h 21m 06.17s , -46d 16m 51.8s) | C | 60 | 19.9 |
46645 | 2025-09-11 07:49:00 | MASTER-OAFA | (05h 21m 04.24s , -46d 15m 24.7s) | C | 60 | 19.9 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 41779
Subject
GRB 250910B: BALROG localization (Fermi Trigger 779223130 / GRB 250910786)
Date
2025-09-10T19:25:58Z (2 days ago)
From
Jochen Greiner at MPE <jcgrog@mpe.mpg.de>
Via
email
T. Preis (University of Innsbruck) & J. Greiner (MPE Garching) report:
The public trigdat data of the Fermi Gamma-ray Burst Monitor (GBM) trigger
779223130 at 18:52:05 on 10 Sept. 2025 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 is:
RA(2000.0) = 74.2 deg
Decl.(2000.0) = -47.5 deg
The 1 sigma statistical error radius is 3.6 deg.
We estimate an additional systematic error of 1 deg.
Further details are available at:
https://grb.mpe.mpg.de/grb/GRB250910786/
The Healpix map can be downloaded from:
https://grb.mpe.mpg.de/grb/GRB250910786/healpix
The location parameters are available as JSON at:
https://grb.mpe.mpg.de/grb/GRB250910786/json
GCN Circular 41778
Subject
GRB 250910B: Fermi GBM Final Real-time Localization
Date
2025-09-10T19:02:42Z (2 days ago)
From
Fermi GBM Team at MSFC/Fermi-GBM <do_not_reply@GIOC.nsstc.nasa.gov>
Via
email
The Fermi GBM team reports the detection of a likely LONG GRB
At 18:52:05 UT on 10 Sep 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250910B (trigger 779223130.045678 / 250910786).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 80.2, Dec = -46.4 (J2000 degrees, equivalent to J2000 05h 20m, -46d 23'), with a statistical uncertainty of 1.0 degrees.
The angle from the Fermi LAT boresight is 35.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250910786/quicklook/glg_skymap_all_bn250910786.png
The HEALPix FITS file, including the estimated localization systematic, can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250910786/quicklook/glg_healpix_all_bn250910786.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250910786/quicklook/glg_lc_medres34_bn250910786.gif