TITLE: GCN CIRCULAR NUMBER: 30693 SUBJECT: GRB 210822A: AstroSat CZTI detection DATE: 21/08/23 09:13:47 GMT FROM: Gaurav Waratkar at IIT,Bombay V. Prasad (IUCAA), P. Sawant (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, 2020, arxiv:2011.07067) showed detection of a bright long GRB 210822A, which was also detected by Swift (Page et al., GCN 30677), GECAM (Wang et al., GCN 30678), and Fermi-LAT (Ohno et al., GCN 30687). 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 2021-08-22 09:18:17.50 UT. The measured peak count rate associated with the burst is 2190 (+85, -91) cts/s above the background in the combined data of four quadrants, with a total of 12961 (+301, -314) cts. The local mean background count rate was 530 (+2, -3) cts/s. Using cumulative rates, we measure a T90 of 10 (+0.2, -0.2) 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 2021-08-22 09:18:18.97 UT. The measured peak count rate is 3587 (+117, -127) cts/s above the background in the combined Veto data of four quadrants, with a total of 24196 (+541, -655) cts. The local mean background count rate was 1799 (+4, -4) cts/s. We measure a T90 of 12 (+0.5, -0.5) 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