TITLE: GCN CIRCULAR NUMBER: 41900 SUBJECT: GRB 250919A / EP250919a: Insight-HXMT detection DATE: 25/09/20 13:01:19 GMT FROM: Chenwei Wang at IHEP <cwwang@ihep.ac.cn> Chen-Wei Wang, Shao-Lin Xiong, Shi-Jie Zheng, and Chao Zheng report on behalf of the Insight-HXMT team: At 2025-09-19T00:29:15.000 (T0), Insight-HXMT/HE detected the burst GRB 250919A, which is also detected by Fermi/GBM (Fermi GBM Team, GCN#41874), SVOM/GRM (Wang et al., GCN#41882), Fermi/LAT (A. Holzmann Airasca, GCN#41884), NuSTAR (G. Waratkar et al., GCN#41888), Glowbug (C.C. Cheung et al., GCN#41891), associated with EP250919a detected by EP/WXT (Liang et al., GCN Circ. 41879). The Insight-HXMT/HE light curve mainly consists of multi-pulses with a T90 of 117.0 +4.5/-3.0 s. The 1s peak rate, measured from T0+10.250 s, is 14624 cnts/sec. The total counts from this burst is 98750 counts. However, the HE detector was suffered from saturation from T0+6 s to T0+8 s and T0+10 s to T0+11 s due to the high-brightness. The HXMT/HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb250919A.png All measurements above are made with the CsI detectors 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/41900. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...