TITLE: GCN CIRCULAR NUMBER: 44311 SUBJECT: GRB 260415A: Insight-HXMT/HE detection DATE: 26/04/16 12:39:40 GMT FROM: renyz16607@163.com Yang-Zhao Ren, Chen-Wei Wang, Cheng-Kui Li, Shao-Lin Xiong, and Chao Zheng (IHEP) report on behalf of the Insight-HXMT team: At 2026-04-15T04:44:27.200 (T0), Insight-HXMT/HE detected a long burst, GRB 260415A, which is also detected by Fermi/GBM (Fermi GBM team, GCN #44299). The Insight-HXMT/HE light curve mainly consists of multi-pulses with T90 of 39 +3/-2 s. The 1s peak rate, measured from T0+0.75 s, is 2212 cnts/sec. Insight-HXMT/HE detected a total of 27305 counts from this burst. The Insight-HXMT /HE light curve can be found here: https://www.bursthub.cn/admin/static/hxmtgrb260415A.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://hxmten.ihep.ac.cn/