TITLE:   GCN CIRCULAR
NUMBER:  41827
SUBJECT: GRB 250911A: Insight-HXMT detection
DATE:    25/09/13 18:17:46 GMT
FROM:    Chenwei Wang at IHEP <cwwang@ihep.ac.cn>

Chen-Wei Wang, Jin-Peng Zhang, Shao-Lin Xiong, and Chao Zheng report on behalf of the Insight-HXMT team:

At 2025-09-11T01:29:28.250 (T0), Insight-HXMT/HE detected the burst GRB 250911A, which is also detected by Swift/BAT (Palmer et al., GCN 41781) and GECAM-B (Zhang et al., GCN#41813.

The Insight-HXMT/HE light curve mainly consists of multi-pulses with a T90 of 24.5 +2.5/-1.5 s. The 1s peak rate, measured from T0+5.250 s, is 1857 cnts/sec. The total counts from this burst is 11720 counts.

The HXMT/HE light curve can be found here:
https://www.bursthub.cn//admin/static/hxmtgrb250911A.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.