TITLE: GCN CIRCULAR NUMBER: 32193 SUBJECT: GRB 220610B: AstroSat CZTI detection DATE: 22/06/12 04:01:10 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 the detection of a long GRB 220610B which was also detected by INTEGRAL SPI-ACS (TrigNum 9952.0) and Fermi-GBM (TrigNum 676537486). The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2022-06-10 07:04:43.50 UTC. The measured peak count rate associated with the burst is 125 (+32, -20) counts/s above the background in the combined data of two quadrants (out of four), with a total of 969 (+230, -221) counts. The local mean background count rate was 226 (+2, -2) counts/s. Using cumulative rates, we measure a T90 of 20 (+7, -8) s. It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2022-06-10 07:04:43.38 UTC. The measured peak count rate is 388 (+69, -71) counts/s above the background in the combined Veto data of four quadrants, with a total of 2179 (+368, -491) counts. The local mean background count rate was 1471 (+5, -5) counts/s. We measure a T90 of 13 (+5, -3) 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. 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.