GRB 230120A: AstroSat CZTI detection

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of GRB 230120A which was also detected by GECAM-B (TrigNum 135). 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 2023-01-20 10:53:13.5 UTC, followed by another strong peak about 100 s later. The measured peak count rate associated with the burst is 139.8 (+28.1 -15.4) counts/s above the background in the combined data of all four quadrants, with a total of 1853 (+441 -318) counts. The local mean background count rate was 124.9 (+0.7 -1.2) counts/s. Using cumulative rates, we measure a T90 of 114.95 (+20.59 -8.86) 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 strong peak at 2023-01-20 10:53:11.6 UTC, followed by another peak about 100 s later. The measured peak count rate is 778.6 (+73.8 -60.0) counts/s above the background in the combined Veto data of all four quadrants, with a total of 12139 (+1359 -1526) counts. The local mean background count rate was 1325.6 (+3.0 -3.3) counts/s. We measure a T90 of 120.35 (+11.00 -11.32) 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.