GCN Circular 37018

G. Waratkar (IITB), A. Dasgupta (BITS Pilani, Hyderabad), J. Joshi (IUCAA), 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 240802A which was also detected by INTEGRAL/SPI-ACS (Trigger 10829) and Konus/WIND (IPN notices).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2024-08-02 10:34:04.5 UTC. The measured peak count rate associated with the burst is 213 (+35, -29) counts/s above the background in the combined data of three quadrants (out of four), with a total of 2026 (+291, -328) counts. We caution that there is a 0.3 s readout dead time in CZT data during the burst which affects the calculated peak count rate and total counts. The local mean background count rate was 259 (+2, -2) counts/s. Using cumulative rates, we measure a T90 of 39 (+3, -8) s.

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 2024-08-02 10:34:07.1 UTC. The measured peak count rate associated with the burst is 205 (+63, -71) counts/s above the background in the combined data of all quadrants, with a total of 4553 (+1494, -1658) counts. The local mean background count rate was 1332 (+9, -9) counts/s. We measure a T90 of 46 (+1, -2) 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