GRB 251013B
GCN Circular 42234
Subject
Fermi GRB 251013B: Global MASTER-Net observations report
Date
2025-10-13T23:31:09Z (2 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-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 251013B ( Fermi GBM team, GCN 42215) errorbox 48818 sec after notice time and 48841 sec after trigger time at 2025-10-13 21:58:28 UT, with upper limit up to 19.4 mag. The observations began at zenith distance = 41 deg. The sun altitude is -49.5 deg.
The galactic latitude b = -52 deg., longitude l = 97 deg.
Real time updated cover map and OT discovered available here:
https://master.sai.msu.ru/site/master2/observ.php?id=3013666
We obtain a following upper limits.
Tmid-T0 | Date Time | Site | Coord (J2000) |Filt.| Expt. | Limit| Comment
_________|_____________________|_____________________|____________________________________|_____|_______|_______|________
48872 | 2025-10-13 21:58:28 | MASTER-SAAO | (23h 34m 30.91s , +04d 40m 04.5s) | C | 60 | 19.4 |
48872 | 2025-10-13 21:58:29 | MASTER-SAAO | (23h 32m 43.17s , +04d 55m 22.1s) | C | 60 | 19.2 |
Filter C is a clear (unfiltred) band.
The observation and reduction will continue.
The message may be cited.
GCN Circular 42219
Subject
GRB 251013B: SVOM/GRM observation
Date
2025-10-13T15:20:56Z (3 days ago)
From
Yue Wang <m18509381757@163.com>
Via
Web form
SVOM/GRM team: Yue Wang, Chen-Wei Wang, Wen-Jun Tan, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Stéphane Schanne (CEA), Hui Yang (IRAP)
Report on behalf of the SVOM team:
SVOM/GRM was triggered on-ground by GRB 251013B at 2025-10-13T08:24:36.250 (T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN #42215).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of mutli-peaks with a T90 of 55 +16/-7 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here:
https://www.bursthub.cn//admin/static/svgrb251013B.png
In addition, the position of this burst, as determined by Fermi/GBM (RA=356.5, DEC=7.5, GCN #42215), is located at about 68.2 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view.
With this localization, the time-averaged spectrum from T0-30 to T0+50 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.63 +0.10/-0.13 and the cutoff energy, parameterized as Epeak, is 324 +567/-129 keV. The event fluence (10-1000 keV) in this time interval is (1.08 +0.09/-0.11)E-05 erg/cm^2.
The localization of GRB 251013B in the 'Amati' relation diagram is shown at:
https://www.bursthub.cn//admin/static/svgrb251013B_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/GRM point of contact for this burst is: Yue Wang (IHEP) (yuewang@ihep.ac.cn)
GCN Circular 42215
Subject
GRB 251013B: Fermi GBM Final Real-time Localization
Date
2025-10-13T08:33:39Z (3 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 08:24:27 UT on 13 Oct 2025, the Fermi Gamma-ray Burst Monitor (GBM) triggered and located GRB 251013B (trigger 782036672.403254 / 251013350).
The on-ground calculated location, using the Fermi GBM trigger data, is RA = 356.5, Dec = 7.5 (J2000 degrees, equivalent to J2000 23h 45m, 7d 30'), with a statistical uncertainty of 5.7 degrees.
The angle from the Fermi LAT boresight is 87.0 degrees.
The skymap can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251013350/quicklook/glg_skymap_all_bn251013350.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/bn251013350/quicklook/glg_healpix_all_bn251013350.fit
The GBM light curve can be found here:
https://heasarc.gsfc.nasa.gov/FTP/fermi/data/gbm/triggers/2025/bn251013350/quicklook/glg_lc_medres34_bn251013350.gif