GRB 250922B
GCN Circular 41966
Subject
GRB 250922B: SVOM/GRM observation
Date
2025-09-24T14:10:14Z (2 days ago)
From
Chenwei Wang at IHEP <cwwang@ihep.ac.cn>
Via
Web form
SVOM/GRM team: Chen-Wei Wang. Wen-Jun Tan, Yue Huang, Shi-Jie Zheng, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Stéphane Schanne (CEA)
Report on behalf of the SVOM team:
SVOM/GRM was triggered on-ground by a burst GRB 250922B at 2025-09-22T21:13:25.900 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN#41944).
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 0.07 +0.05/-0.03 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb250922B.png
In addition, the position of this burst, as determined by Fermi/GBM (RA= 48.7, DEC= 30.7, GCN#41944), is located at about 52 degrees from the SVOM optical axis, which is just outside the ECLAIRs field of view.
With this localization, the time-averaged spectrum from T0-0.2 to T0+0.1 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.15 +0.12/-0.15 and the cutoff energy, parameterized as Epeak, is 1060 +110/-460 keV. The event fluence (10-1000 keV) in this time interval is (4.38 +0.55/-0.53)E-07 erg/cm^2. The 'Amati' relation of GRB 250922B is shown at:
https://www.bursthub.cn//admin/static/svgrb250922B_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 41949
Subject
Fermi GRB 250922B: Global MASTER-Net observations report
Date
2025-09-23T00:15:31Z (4 days 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-Kislovodsk robotic telescope (Global MASTER-Net: http://observ.pereplet.ru, Lipunov et al., 2010, Advances in Astronomy, vol. 2010, 30L) located in Russia (Lomonosov MSU, Kislovodsk Solar Station of Pulkovo observatory) started inspect of the Fermi GRB 250922B ( Fermi GBM team, GCN 41944) errorbox 5589 sec after notice time and 5627 sec after trigger time at 2025-09-22 22:47:13 UT, with upper limit up to 18.8 mag. The observations began at zenith distance = 30 deg. The sun altitude is -41.0 deg.
The galactic latitude b = -22 deg., longitude l = 156 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2997538
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
5658 | 2025-09-22 22:47:13 | MASTER-Kislovodsk | (02h 52m 08.73s , +16d 41m 59.3s) | C | 60 | 18.8 |
5658 | 2025-09-22 22:47:13 | MASTER-Kislovodsk | (02h 56m 55.92s , +16d 18m 34.3s) | C | 60 | 18.7 |
6457 | 2025-09-22 23:00:32 | MASTER-Kislovodsk | (02h 52m 08.19s , +16d 41m 21.3s) | C | 60 | 18.7 |
6457 | 2025-09-22 23:00:32 | MASTER-Kislovodsk | (02h 56m 45.35s , +16d 19m 01.1s) | C | 60 | 18.8 |
7065 | 2025-09-22 23:10:41 | MASTER-Kislovodsk | (02h 52m 03.78s , +16d 43m 29.5s) | C | 60 | 18.7 |
7065 | 2025-09-22 23:10:41 | MASTER-Kislovodsk | (02h 56m 46.03s , +16d 21m 14.1s) | C | 60 | 18.7 |
7673 | 2025-09-22 23:20:48 | MASTER-Kislovodsk | (02h 52m 13.12s , +16d 43m 24.9s) | C | 60 | 18.6 |
7673 | 2025-09-22 23:20:48 | MASTER-Kislovodsk | (02h 56m 52.90s , +16d 21m 12.4s) | C | 60 | 18.5 |
8471 | 2025-09-22 23:34:06 | MASTER-Kislovodsk | (02h 52m 00.64s , +16d 41m 56.3s) | C | 60 | 18.6 |
8471 | 2025-09-22 23:34:06 | MASTER-Kislovodsk | (02h 56m 50.35s , +16d 19m 34.7s) | C | 60 | 18.4 |
9420 | 2025-09-22 23:49:55 | MASTER-Kislovodsk | (02h 39m 41.84s , +18d 28m 07.8s) | C | 60 | 18.8 |
9420 | 2025-09-22 23:49:55 | MASTER-Kislovodsk | (02h 34m 54.00s , +18d 49m 39.5s) | C | 60 | 18.7 |
9916 | 2025-09-22 23:58:11 | MASTER-Kislovodsk | (02h 53m 47.82s , +18d 37m 01.6s) | C | 60 | 18.7 |
9916 | 2025-09-22 23:58:11 | MASTER-Kislovodsk | (02h 58m 39.92s , +18d 14m 12.0s) | C | 60 | 18.6 |
10088 | 2025-09-23 00:01:03 | MASTER-Kislovodsk | (02h 39m 42.06s , +18d 28m 10.1s) | C | 60 | 18.7 |
10088 | 2025-09-23 00:01:03 | MASTER-Kislovodsk | (02h 34m 54.63s , +18d 49m 36.5s) | C | 60 | 18.7 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 41944
Subject
GRB 250922B: Fermi GBM Final Real-time Localization
Date
2025-09-22T21:24:08Z (4 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 SHORT GRB
At 21:13:25 UT on 22 Sep 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250922B (trigger 780268410.863384 / 250922884).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 48.7, Dec = 30.7 (J2000 degrees, equivalent to J2000 03h 14m, 30d 41'), with a statistical uncertainty of 13.4 degrees.
The angle from the Fermi LAT boresight is 90.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250922884/quicklook/glg_skymap_all_bn250922884.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/bn250922884/quicklook/glg_healpix_all_bn250922884.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250922884/quicklook/glg_lc_medres34_bn250922884.gif