TITLE: GCN CIRCULAR NUMBER: 31987 SUBJECT: GRB 220430A: AstroSat CZTI detection DATE: 22/05/02 07:40:42 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 220430A which was also reported by Swift (Ambrosi et al., GCN 31972; Osborne et al., GCN 31973; Barthelmy et al., GCN 31981), and AGILE (Ursi et al., GCN 31975). The source was clearly detected in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2022-04-30 13:53:58.50 UT. The measured peak count rate associated with the burst is 892 (+60, -62) counts/s above the background in the combined data of all the quadrants, with a total of 11896 (+669, -639) counts. The local mean background count rate was 484 (+2, -2) counts/s. Using cumulative rates, we measure a T90 of 40 (+4, -2) s. It was also 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 2022-04-30 13:53:58.52 UT. The measured peak count rate is 3131 (+109, -98) counts/s above the background in the combined Veto data of four quadrants, with a total of 48203 (+1134, -1252) counts. The local mean background count rate was 1614 (+3, -5) counts/s. We measure a T90 of 41 (+1, -2) 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