TITLE: GCN CIRCULAR NUMBER: 42580 SUBJECT: GRB 251028A: Insight-HXMT/HE detection DATE: 25/11/04 15:24:23 GMT FROM: guohx@ihep.ac.cn Hao-Xuan Guo, Chen-Wei Wang, Cheng-Kui Li, Shao-Lin Xiong, and Chao Zheng (IHEP) report on behalf of the Insight-HXMT team: At 2025-10-28T03:26:40.000 (T0), Insight-HXMT/HE detected a long burst, GRB 251028A, which is also detected by Fermi/GBM (Fermi GBM team, GCN#42497, GCN#42499), MAXI/GSC (MAXI team, GCN#42498), Glowbug (C.C. Cheung et al., GCN#42506), SVOM/GRM (SVOM/GRM team, SVOM/ECLAIRs team, GCN#42522), GECAM-B (GECAM team, GCN#42523), and Konus-Wind (Konus-Wind team, GCN#42527). The Insight-HXMT/HE light curve mainly consists of a single pulse with a T90 of 80 +21/-30 s. The 1s peak rate, measured from T0-4.5 s, is 450 cnts/sec. Insight-HXMT/HE detected a total of 9154 counts from this burst. The Insight-HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb251028A.png All measurements above are made with the CsI detectors of Insight-HXMT/HE operating in the regular mode with the energy range of about 60-900 keV (deposited energy). Only gamma-rays with energy greater than about 200 keV can penetrate the spacecraft and leave signals in the CsI detectors installed inside of the telescope. Insight-HXMT is the first Chinese space X-ray telescope, which was funded jointly by the China National Space Administration (CNSA) and the Chinese Academy of Sciences (CAS). More information about it could be found at: http://www.hxmt.org View this GCN Circular online at https://gcn.nasa.gov/circulars/42580. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...