GRB 260327A

Xue-Yuan Zao, Chen-Wei Wang, Cheng-Kui Li, Shao-Lin Xiong, and Chao Zheng (IHEP) report on behalf of the Insight-HXMT team:

At 2026-03-27T02:28:50.350 (T0), Insight-HXMT/HE detected a long burst, GRB 260327A, which is also detected by AstroSat CZTI (A. Arya et. al., GCN #44130
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 ) and Konus-Wind (IPN notice).

The Insight-HXMT/HE light curve mainly consists of two emission episodes with a total duration (T90) of 98 +14/-6 s. The 1s peak rate, measured from T0-1 s, is 2435 cnts/sec. Insight-HXMT/HE detected a total of 22378 counts from this burst.  

The Insight-HXMT /HE light curve can be found here: 
https://www.bursthub.cn//admin/static/hxmtgrb260327A.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/

A. Arya (IITB), A. Goyal (IITB), S. Salunke (IUCAA), Harsha K. H. (IUCAA), M. Tembhurnikar (IUCAA), G. Waratkar (Caltech/IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 260327A which was also detected by Konus-Wind (IPN Notices).

The source was clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve shows two emission episodes: a fainter episode preceding a brighter, longer episode by ~50 s. The brighter episode peaks at 2026-03-27 02:28:49.45 UTC. The measured peak count rate associated with the burst is 526 (+68, -68) counts/s above the background in the combined data of all quadrants, with a total of 7557 (+1305, -1387) counts. The local mean background count rate was 1236 (+5, -5) counts/s. We measure a T90 of 88 (+3, -4) s from the cumulative Veto light curve for both episodes.

The source was also faintly detected in the 20-200 keV energy range.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb