TITLE:   GCN CIRCULAR
NUMBER:  42013
SUBJECT: GRB 250926A: Insight-HXMT detection
DATE:    25/09/27 15:01:50 GMT
FROM:    Chenwei Wang at IHEP <cwwang@ihep.ac.cn>

Chen-Wei Wang, Cheng-Kui Li, Shao-Lin Xiong, and Chao Zheng report on behalf of the Insight-HXMT team:

At 2025-09-26T00:21:24.600 (T0), Insight-HXMT/HE was trigger by the burst GRB 250926A, which is also detected by Fermi/GBM (Fermi GBM Team, GCN#41993) and AstroSat (A. Goyal et al., GCN#42008).

The Insight-HXMT/HE light curve mainly consists of a precursor followed by a main pulse with a T90 of 2.1 +2.3/-0.7 s. The 1s peak rate, measured from T0-0.050 s, is 3838 cnts/sec. The total counts from this burst is 4746 counts.

The HXMT/HE light curve can be found here:
https://www.bursthub.cn//admin/static/hxmtgrb250926A.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.