TITLE: GCN CIRCULAR NUMBER: 42762 SUBJECT: GRB 251117A: Insight-HXMT/HE detection DATE: 25/11/19 15:10:34 GMT FROM: Yue Wang Yue Wang, Chen-Wei Wang, Chao Zheng, and Shao-Lin Xiong (IHEP) report on behalf of the Insight-HXMT team: At 2025-11-17T12:19:52.500 (T0), Insight-HXMT/HE detected a short-duration GRB 251117A, which is also detected by Fermi/GBM (Fermi GBM Team, GCN #42719), Fermi/LAT (A. Holzmann Airasca et. al., GCN #42729) and SVOM/GRM (Yue Wang et. al., GCN #42731). The Insight-HXMT/HE light curve mainly consists of multiple peaks with a T90 of 2.3 +2.2/-1.1 s. The 1s peak rate, measured from T0-0.05 s, is 1167 cnts/sec. Insight-HXMT/HE detected a total of 1604 counts from this burst. The Insight-HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb251117A.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