TITLE: GCN CIRCULAR NUMBER: 39602 SUBJECT: GRB 250305A: SVOM/GRM observation of a burst DATE: 25/03/06 09:51:52 GMT FROM: zhangjinpeng@ihep.ac.cn
SVOM/GRM team: Jin-Peng Zhang, Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Nicolas Dagoneau (CEA), Maria-Grazia Bernardini (INAF-OAB), Jean-Luc Atteia (IRAP), Frédéric Piron (LUPM)
Report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by GRB 250305A (SVOM burst-id sb25030508) at 2025-03-05T15:28:58.100 (T0), which was also observed by Fermi/GBM (Fermi GBM team, GCN #39597).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of multi-pulses with a T90 of 4.6 +1.5/-0.9 s in the 15-5000 keV band.
In addition, the position of this burst, as determined by Fermi/GBM (GCN #39597, RA: 223.7 deg, DEC: -3.0 deg, Error: 5.0 deg), is located at about 63 degrees from the SVOM optical axis, and outside the ECLAIRs field of view.
The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250305A.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: Jin-Peng Zhang (IHEP) (zhangjinpeng@ihep.ac.cn)
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