TITLE:   GCN CIRCULAR
NUMBER:  46065
SUBJECT: GRB 261024D: Insight-HXMT/HE detection
DATE:    26/10/28 04:41:34 GMT
FROM:    Xinghao Luo at IHEP <2952704891@qq.com>

Xing-Hao Luo, Chen-Wei Wang, Chao Zheng, and Shao-Lin Xiong (IHEP) report on behalf of the Insight-HXMT team:

At 2026-10-24T21:33:06.850 (T0), Insight-HXMT/HE detected the GRB 261024D, which is also detected by AstroSat CZTI (A. Goyal et.al., GCN#46040), NuSTAR (G. Waratkar et.al, GCN#46051), Glowbug gamma-ray telescope (C. C. Cheung et.al., GCN#46053), and GECAM-B (Xing-Hao Luo et.al., GCN#46061).
	
The Insight-HXMT/HE light curve mainly consists of multiple pulses with a T90 of 9.0 +1.5/-0.5 s. The 1s peak rate, measured from T0+0.25 s, is 2957 cnts/sec. Insight-HXMT/HE detected a total of 11613 counts from this burst.

The HXMT/HE light curve can be found here:
https://www.bursthub.cn/gcn/2026/hxmtgrb261024D.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/