TITLE:   GCN CIRCULAR
NUMBER:  44245
SUBJECT: GRB 260407A: Insight-HXMT/HE detection
DATE:    26/04/09 11:05:54 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 2026-04-07T09:11:07.000 (T0), Insight-HXMT/HE detected a long burst, GRB 260407A, which is also detected by Fermi GBM (GCN #44226), Glowbug (C.C. Cheung et al., GCN #44237) and CALET (M. L. Cherry et al., GCN #44242).

The Insight-HXMT/HE light curve mainly consists of a single pulse with a total duration (T90) of 23.5 +16/-9 s. The 1s peak rate, measured from T0+0.25 s, is 493 cnts/sec. Insight-HXMT/HE detected a total of 4651 counts from this burst.

The Insight-HXMT /HE light curve can be found here:
https://www.bursthub.cn//admin/static/hxmtgrb260407A.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/