GCN Circular 36858

A. Dasgupta (BITS Hyderabad), G. Waratkar (IITB), 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 240713B. Inspection of INTEGRAL/SPI-ACS data also showed the detection of the burst. We note that while the GOES data shows solar activity around this time, the Sun was Earth-occulted for CZTI.

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2024-07-13 23:34:53.5 UTC. The measured peak count rate associated with the burst is 178 (+37, -32) counts/s above the background in the combined data of all quadrants, with a total of 1630 (+300, -282) counts. The local mean background count rate was 324 (+2, -3) counts/s. Using cumulative rates, we measure a T90 of 19 (+9, -6) s.

It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2024-07-13 23:34:52.2 UTC. The measured peak count rate is 456 (+68, -69) counts/s above the background in the combined Veto data of all quadrants, with a total of 4210 (+558, -603) counts. The local mean background count rate was 1342 (+5, -5) counts/s. We measure a T90 of 22 (+7, -5) 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