TITLE: GCN CIRCULAR NUMBER: 39335 SUBJECT: GRB 250215A: SVOM/GRM observation DATE: 25/02/15 11:26:40 GMT FROM: zhengchao_astro@foxmail.com
SVOM/GRM team: Chao Zheng, Chen-wei Wang, Shi-Jie Zheng, Shao-Lin Xiong, Yue Huang, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Frédéric Piron (LUPM), Nicolas Dagoneau (CEA), Maria-Grazia Bernardini (INAF-OAB), Jean-Luc Atteia (IRAP)
report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by a long burst GRB 250215A (sb25021501) at 2025-02-15T02:32:03.300 UTC (T0), which was also observed by Fermi/GBM (Fermi GBM team, GCN #39327), AstroSat (M. Tembhurnikar et al., GCN #39334) and INTEGRAL (Patrizia Barria et al., GCN 39331).
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 about 29.8 +7.8/-8.0 seconds in the 15-5000 keV band.
The time-averaged spectrum from T0-25 to T0+25 s could be fit by a power law with high energy exponential cutoff function. The power law index is -1.39 +/- 0.15 and the cutoff energy, parameterized as Epeak, is 134 +/- 36 keV. The event fluence (10-1000 keV) in this time interval is (6.02 +/- 0.47)E-06 erg/cm^2.
The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250215A.png
In addition, the position of this burst, as determined by EP/WXT (Wang et al., GCN #39329), is located at about 72 degrees from the SVOM optical axis, and 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/GRM point of contact for this burst is: Chao Zheng (IHEP) (zhengchao97@ihep.ac.cn)
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