TITLE: GCN CIRCULAR NUMBER: 32028 SUBJECT: GRB 220511A: AstroSat CZTI detection DATE: 22/05/12 11:33:37 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 GRB 220511A which was also reported by Fermi GBM (GCN #32018), AGILE (Ursi et al., GCN #32021), and Swift/BAT-GUANO (DeLaunay et al., GCN #32023). The source was clearly detected in the 20-200 keV energy range. The light curve peaked at 2022-05-11 13:41:57.45 UT. The measured peak count rate associated with the burst is 802 (+197, -74) counts/s above the background in the combined data of four quadrants, with a total of 1126 (+156, -184) counts. The local mean background count rate was 525 (+9, -9) counts/s. Using cumulative rates, we measure a T90 of 1.8 (+0.8, -0.4) s. It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=grb. 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.