GRB 250826A
GCN Circular 41566
Subject
GRB 250826A: SVOM/GRM observation
Date
2025-08-27T16:10:33Z (a month ago)
From
Chenwei Wang at IHEP <cwwang@ihep.ac.cn>
Via
Web form
SVOM/GRM team: Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Sebastien Guillot (IRAP), Frédéric Piron (CEA)
Report on behalf of the SVOM team:
SVOM/GRM was triggered on-ground by GRB 250826A at 2025-08-26T07:24:03.000 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN #41545).
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 8.0 +4.0/-1.5 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb250826A.png
In addition, the position of this burst, as determined by Fermi/GBM (RA = 141.8, Dec = 34.7, GCN #41545), is located at about 136 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view.
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 41551
Subject
Fermi GRB 250826A: Global MASTER-Net observations report
Date
2025-08-27T00:30:41Z (a month 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 250826A ( Fermi GBM team, GCN 41545) errorbox 61289 sec after notice time and 61324 sec after trigger time at 2025-08-27 00:26:06 UT, with upper limit up to 16.5 mag. The observations began at zenith distance = 80 deg. The sun altitude is -20.9 deg.
The galactic latitude b = 47 deg., longitude l = 190 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=2977441
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
61355 | 2025-08-27 00:26:06 | MASTER-Kislovodsk | (09h 12m 54.84s , +37d 15m 47.2s) | C | 60 | 16.2 |
61355 | 2025-08-27 00:26:06 | MASTER-Kislovodsk | (09h 17m 46.54s , +36d 51m 26.0s) | C | 60 | 16.5 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 41545
Subject
GRB 250826A: Fermi GBM Final Real-time Localization
Date
2025-08-26T07:34:29Z (a month 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 07:24:01 UT on 26 Aug 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 250826A (trigger 777885846.969916 / 250826308).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 141.8, Dec = 34.7 (J2000 degrees, equivalent to J2000 09h 27m, 34d 42'), with a statistical uncertainty of 3.6 degrees.
The angle from the Fermi LAT boresight is 40.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250826308/quicklook/glg_skymap_all_bn250826308.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/bn250826308/quicklook/glg_healpix_all_bn250826308.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn250826308/quicklook/glg_lc_medres34_bn250826308.gif