TITLE: GCN CIRCULAR NUMBER: 31412 SUBJECT: GRB 220107B: AstroSat CZTI detection DATE: 22/01/08 13:20:02 GMT FROM: Gaurav Waratkar at IIT,Bombay A. Suresh (IITB), 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 220107B, which was also detected by Fermi-GBM (trigger 663274898/220107793), Fermi-LAT (Axelsson et al., GCN 31409) and Swift-XRT (Gropp et al., GCN 31411). 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 2022-01-07 19:01:45.50 UT. Quadrant B was noisy, and we exclude it from further analysis. The measured peak count rate associated with the burst is 372 (+44 -42) cts/s above the background in the combined data of three quadrants (out of four), with a total of 2558 (+225 -239) cts. The local mean background count rate was 382 (+2 -2) cts/s. Using cumulative rates, we measure a T90 of 19 (+3 -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 2022-01-07 19:01:35.775 UT. The measured peak count rate is 826 (+81 -85) cts/s above the background in the combined Veto data of four quadrants, with a total of 5424 (+496 -555) cts. The local mean background count rate was 1721 (+4 -5) cts/s. We measure a T90 of 22 (+2 -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 [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