TITLE:   GCN CIRCULAR
NUMBER:  36000
SUBJECT: GRB 240331A: AstroSat CZTI detection
DATE:    24/04/01 10:25:36 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar24@gmail.com>

J. Joshi (IUCAA), G. Waratkar (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-duration GRB 240331A which was also detected by the Fermi-GBM (Fermi-GBM Team, GCN Circ. 35998).

The source was clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2024-03-31 23:55:20.01 UTC. The measured peak count rate associated with the burst is 266 (+69, -53) counts/s above the background in the combined data of all quadrants, with a total of 1926 (+501, -548) counts. The local mean background count rate was 1448 (+8, -9) counts/s. We measure a T90 of 20 (+2, -6) s from the cumulative Veto light curve.

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