TITLE: GCN CIRCULAR NUMBER: 40683 SUBJECT: GRB 250610B: SVOM/GRM analysis DATE: 25/06/11 06:39:58 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: A. Saccardi, J. Rodriguez, N. Dagoneau (CEA)
Report on behalf of the SVOM team:
SVOM/GRM detected the burst GRB 250610B at 2025-06-10T16:32:58 UTC (T0), which is also detected by SVOM/ECLAIRs (A. Saccardi et al., GCN #40671) and Fermi/GBM (Yun Wang et al., GCN #40682)
With the event-by-event data downloaded through the X-band ground station, we conducted the standard analysis pipeline of GRB 250610B. The GRM light curve shows that this burst consists of a single pulse with a T90 of 94 +/-14 s in the 15-5000 keV band.
The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250610B.png
With the localization of ECLAIRs (RA=200.1831, DEC=31.1028), the time-averaged spectrum from T0-10 to T0+80 s is best fitted by a Blackbody function. The temperature, parameterized as kT, is 13 +/- 1 keV. The event fluence (10-1000 keV) in this time interval is (2.3 +/- 0.2)E-06 erg/cm^2.
The time-averaged spectrum can also be fitted by a power law function with an exponential high-energy cutoff adequately. The power law index is -1.2 +/- 0.5 and the cutoff energy, parameterized as Epeak, is 66 +15/-12 keV. The event fluence (10-1000 keV) in this time interval is (2.2 +/- 0.3)E-06 erg/cm^2. Thus GRB 250610B is consistent with Type II GRBs in the 'Amati' relation diagram, as shown at: https://www.bursthub.cn//admin/static/grb250610B_amati.png
We note that the calibration of SVOM/GRM is undergoing thus these results are preliminary. 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/GRM point of contact for this burst is: Chen-Wei Wang (IHEP) (cwwang@ihep.ac.cn)
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