TITLE: GCN CIRCULAR NUMBER: 43299 SUBJECT: GRB 251230A / EP251230a: Insight-HXMT/HE detection DATE: 26/01/02 12:17:17 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 2025-12-30T01:22:22.000 (T0), Insight-HXMT/HE detected a burst, GRB 251230A / EP251230a, which is also detected by Swift (Lanava et al., GCN #43252) and EP-WXT (Li et al., GCN #43255 and Wang et al., GCN #43272). The Insight-HXMT/HE light curve mainly consists of multiple pulses with T90 of 54.4 +11.6/-8.4 s. The 1s peak rate, measured from T0-0.70 s, is 797 cnts/sec. Insight-HXMT/HE detected a total of 10,311 counts from this burst. The Insight-HXMT /HE light curve can be found here: https://www.bursthub.cn//admin/static/hxmtgrb251230A.png All measurements above are made with the CsI detectors of Insight-HXMT/HE operating in the Low-Gain mode with the energy range of about 300-3000 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/43299. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...