TITLE: GCN CIRCULAR NUMBER: 42893 SUBJECT: GRB 251128A: Insight-HXMT/HE detection DATE: 25/11/29 14:43:15 GMT FROM: zhangjinpeng@ihep.ac.cn Jin-Peng Zhang, Chen-Wei Wang, Chao Zheng, and Shao-Lin Xiong (IHEP) report on behalf of the Insight-HXMT team: At 2025-11-28T04:22:22.000 (T0), Insight-HXMT/HE detected a long GRB 251128A, which is also detected by Fermi/GBM (Fermi GBM Team, GCN #42865). The Insight-HXMT/HE light curve mainly consists of multiple pulses with a T90 of 44 +11/-18 s. The 1s peak rate, measured from T0+9.5 s, is 604 cnts/sec. Insight-HXMT/HE detected a total of 3694 counts from this burst. The Insight-HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb251128A.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/42893. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...