TITLE:   GCN CIRCULAR
NUMBER:  45738
SUBJECT: GRB 260923A: Insight-HXMT/HE detection
DATE:    26/09/25 04:25:59 GMT
FROM:    yzh807926@163.com

Zheng-Hang Yu, Wen-Jun Tan and Shao-Lin Xiong (IHEP) report on behalf of the Insight-HXMT team:

At 2026-09-23T23:41:36 (T0), Insight-HXMT/HE detected GRB 260923A, which is also detected by Fermi/GBM (Fermi GBM team, GCN #45710)

The Insight-HXMT/HE light curve mainly consists of multiple pulses with a T90 of 13.8 +8.0/-4.2 s. The 1 s peak rate, measured from T0+30 s, is 667.90 cnts/sec. Insight-HXMT/HE detected a total of 4029 counts from this burst.

The Insight-HXMT/HE light curve can be found here:
https://www.bursthub.cn/gcn/2026/9/hxmtgrb260923A.png

All measurements above are made with the CsI detectors of Insight-HXMT/HE operating in the Normal 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