TITLE: GCN CIRCULAR NUMBER: 40708 SUBJECT: GRB 250612C: SVOM/GRM observation an intermedium duration burst DATE: 25/06/12 16:01:33 GMT FROM: Chenwei Wang at IHEP cwwang@ihep.ac.cn
SVOM/GRM team: Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)
SVOM/ECLAIRs team: Ulysse Jacob (LUPM), Jean-Luc Atteia (IRAP)
Report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by a bright burst GRB 250612C (SVOM trigger reference: sb25061214) at 2025-06-12T14:53:16.700 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN#40704).
The real-time alert data and light curves of SVOM/GRM were downlinked to the ground through the VHF system with low latency. With the VHF data, the GRM light curve shows that this burst consists of a single spike with a T90 of 2.4 +/-0.8 s in the 15-5000 keV band. This burst is clearly detected in GRM VHF data beyond 550 keV, indicating a hard spectrum.
The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250612C.png
At the time of the burst, ECLAIRs was not taking data.
Refined analysis will be reported later.
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)
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