TITLE: GCN CIRCULAR NUMBER: 41386 SUBJECT: GRB 250814B: SVOM/GRM observation DATE: 25/08/15 09:29:26 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: Hui Yang (IRAP), Stéphane Schanne (CEA) Report on behalf of the SVOM team: SVOM/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). With 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. The SVOM/GRM light curve can be found here: https://www.bursthub.cn//admin/static/svgrb250814B.png The SVOM/GRM on-ground localization of this burst is (J2000): RA: 73.9 deg DEC: 22.2 deg Error: 7.1 deg (1sigma, statistical only) We 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) In 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. With 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: https://www.bursthub.cn//admin/static/grb250814B_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) View this GCN Circular online at https://gcn.nasa.gov/circulars/41386. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...