TITLE: GCN CIRCULAR NUMBER: 32140 SUBJECT: GRB 220527A: AstroSat CZTI detection DATE: 22/05/28 05:23:18 GMT FROM: Gaurav Waratkar at IIT,Bombay R. Gopalakrishnan (IUCAA), V. Prasad (IUCAA), G. Waratkar (IITB), 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 detection of a long GRB 220527A which was also reported by AGILE (Ursi et al. GCN 32129), Fermi-GBM (GCN 32130), Fermi-LAT (Bissaldi et al., GCN 32131), Swift-XRT (Sbarufatti et al., GCN 32135), Swift-UVOT (Tohuvavohu et al., GCN 32136) and CALET (Yamaoka et al., GCN 32139). 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 2022-05-27 09:17:23.55 UTC. The measured peak count rate associated with the burst is 1879 (+251, -171) counts/s above the background in the combined data of four quadrants, with a total of 5318 (+224, -235) counts. The local mean background count rate was 496 (+4, -5) counts/s. Using cumulative rates, we measure a T90 of 7 (+1, -1) 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 2022-05-27 09:17:19.39 UTC. The measured peak count rate is 1880 (+96, -93) counts/s above the background in the combined Veto data of four quadrants, with a total of 11483 (+534, -559) counts. The local mean background count rate was 1644 (+6, -6) counts/s. We measure a T90 of 14 (+3, -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, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project. Links: ------ [1] http://astrosat.iucaa.in/czti/?q=grb