{
  "circularId": 41386,
  "format": "text/plain",
  "submitter": "Chenwei Wang at IHEP <cwwang@ihep.ac.cn>",
  "bibcode": "2025GCN.41386....1S",
  "createdOn": 1755250166936,
  "subject": "GRB 250814B: SVOM/GRM observation",
  "eventId": "GRB 250814B",
  "body": "SVOM/GRM team: Chen-Wei Wang, Shi-Jie Zheng, Yue Huang, Shao-Lin Xiong, Shuang-Nan Zhang (IHEP)\n\nSVOM/ECLAIRs team: Hui Yang (IRAP), Stéphane Schanne (CEA)\n\nReport on behalf of the SVOM team:\n\nSVOM/GRM was triggered on-ground by GRB 250814B at 2025-08-14T10:22:10.500 UTC (T0), which is also detected by Fermi/GBM (Fermi GBM Team, GCN #41366).\n\nWith the event-by-event data downloaded through the X-band ground station, the GRM light curve shows that this burst consists of a single pulse with a T90 of 9.0 +2.0/-3.0 s in the 15-5000 keV band.\n\nThe SVOM/GRM light curve can be found here:\nhttps://www.bursthub.cn//admin/static/svgrb250814B.png\n\nThe SVOM/GRM on-ground localization of this burst is (J2000):\nRA: 73.9 deg\nDEC: 22.2 deg\nError: 7.1 deg (1sigma, statistical only)\nWe caution that the calibration of SVOM/GRM is undergoing and this localization is subject to systematic errors. The SVOM/GRM on-ground localization is consistent with Fermi/GBM (Fermi GBM Team, GCN #41366)\n\nIn addition, the position of this burst, as determined by SVOM/GRM, is located at about 71 degrees from the SVOM optical axis, which is outside the ECLAIRs field of view, and is consistent with no indication for subthreshold targets either from CRT and IMT of ECLAIRs.\n\nWith this localization, the time-averaged spectrum from T0-5 to T0+7 s is best fitted by a power law function with an exponential high-energy cutoff. The power law index is -1.46 +0.16/-0.22 and the cutoff energy, parameterized as Epeak, is 250 +395/-91 keV. The event fluence (10-1000 keV) in this time interval is (2.99 +0.43/-0.41)E-06 erg/cm^2. Thus GRB 250814B is consistent with Type II GRBs in the 'Amati' relation diagram, as shown at:  \nhttps://www.bursthub.cn//admin/static/grb250814B_amati.png\n\nThe 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.\n\nThe SVOM point of contact for this burst is: Chen-Wei Wang (IHEP)(cwwang@ihep.ac.cn)\n",
  "submittedHow": "web"
}