TITLE:   GCN CIRCULAR
NUMBER:  43865
SUBJECT: GRB 260226A: Insight-HXMT/HE detection of the very bright burst
DATE:    26/02/27 16:11:28 GMT
FROM:    yzh807926@163.com

Zheng-Hang Yu, Chen-Wei Wang and Shao-Lin Xiong (IHEP) report on behalf of the Insight-HXMT team:

At 2026-02-26T10:38:11.100 (T0), Insight-HXMT/HE detected the long bright burst GRB 260226A, which is also detected by Fermi/GBM (Fermi GBM Team, GCN #43840), Fermi/LAT(D. Depalo et al., GCN #43844) , AstroSat-CZTI (Harsha et al., GCN #43846), Glowbug (Woolf et al., GCN #43855), CALET-GBM (Kobayashi et al., GCN #43860), and Konus-Wind(D. Svinkin et al., GCN #43864)
	
The Insight-HXMT/HE light curve mainly consists of two eposides with a T90 of about 76 s. The 1s peak rate, measured from T0+1.5 s, is 15858 cnts/sec. Insight-HXMT/HE detected a total of 264251 counts form this burst. However, the HE detector was suffered from saturation during the brightest peak due to the high-brightness.

The HXMT/HE light curve can be found here:
https://www.bursthub.cn//admin/static/hxmtgrb260226A.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/