TITLE: GCN CIRCULAR NUMBER: 41072 SUBJECT: GRB 250711A: SVOM/GRM observation DATE: 25/07/12 09:36:26 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: Olivier Godet, Sébastien Guillot (IRAP)
Report on behalf of the SVOM team:
SVOM/GRM was triggered in-flight by a bright burst GRB 250711A (SVOM trigger reference: sb25071104) at 2025-07-11T14:40:14.00 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN#41064).
With the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of double pulses with a T90 of 38.5 +/-4.0 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250711A.png
In addition, the position of this burst, as determined by Fermi/GBM (RA= 261.2, DEC= 44.9, GCN#41064), is located at about 48 degrees from the SVOM optical axis, which is just outside the ECLAIRs field of view.
With this localization, the time-averaged spectrum from T0-10 to T0+70 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.20 +0.09/-0.10 and the cutoff energy, parameterized as Epeak, is 146 +23/-17 keV. The event fluence (10-1000 keV) in this time interval is (1.69 +0.12/-0.10)E-05 erg/cm^2.
The localization of GRB 250620C in the 'Amati' relation diagram is shown at: https://www.bursthub.cn//admin/static/grb250711A_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 point of contact for this burst is: Chen-Wei Wang (IHEP)(cwwang@ihep.ac.cn)
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