GRB 240720A: AstroSat CZTI detection

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of GRB 240720A which was also detected by Swift/BAT (Gupta et al., GCN Circ. 36909), Fermi/GBM (Fletcher et al., GCN Circ. 36910), and INTEGRAL/SPI-ACS (Trigger 10797). The source was detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2024-07-20 00:24:52.25 UTC. The measured peak count rate associated with the burst is 121 (+42, -36) counts/s above the background in the combined data of three quadrants (out of four), with a total of 212 (+72, -75) counts. The local mean background count rate was 226 (+5, -6) counts/s. Using cumulative rates, we measure a T90 of 2.7 (+0.9, -1.1) s. The source was also detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2024-07-20 00:24:51.63 UTC. The measured peak count rate associated with the burst is 381 (+66, -71) counts/s above the background in the combined data of all quadrants, with a total of 598 (+150, -160) counts. The local mean background count rate was 1281 (+8, -8) counts/s. We measure a T90 of 2.2 (+0.3, -0.9) s from the cumulative Veto light curve. 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. CZTI GRB detections are reported regularly on the payload site at: http://astrosat.iucaa.in/czti/?q=grb