//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 31788 SUBJECT: GRB 220324A: AstroSat CZTI detection DATE: 22/03/25 17:47:32 GMT FROM: Gaurav Waratkar at IIT,Bombay R. Gopalakrishnan (IUCAA), V. Prasad (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (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 detection of a long GRB 220324A which was also detected by Fermi - GBM (Trigger Number - 669782349). The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2022-03-24 02:39:09.50 UT. The measured peak count rate associated with the burst is 200 (+44, -28) counts/s above the background in the combined data of all four quadrants, with a total of 2304 (+346, -331) counts. The local mean background count rate was 502 (+2, -2) counts/s. Using cumulative rates, we measure a T90 of 22 (+5, -4) s. It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed a single peak of emission at 2022-03-24 02:38:00.95 UT. The measured peak count rate is 169 (+83, -10) counts/s above the background in the combined Veto data of four quadrants, with a total of 1428 (+566, -627) counts. The local mean background count rate was 1687 (+5, -6) counts/s. We measure a T90 of 18 (+5, -9) s from the cumulative Veto light curve. CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb [1]. CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, ISAC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. Links: ------ [1] http://astrosat.iucaa.in/czti/?q=grb