TITLE: GCN CIRCULAR NUMBER: 27425 SUBJECT: GRB 200317A: AstroSat CZTI detection DATE: 20/03/24 12:16:53 GMT FROM: Soumya Gupta at IUCAA/ASTROSAT S. Gupta, V. Sharma, A. Vibhute and D. Bhattacharya (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data showed the detection of a GRB 200317A, which was also detected by Fermi GBM (GCN #27392) and Global MASTER-Net (Lipunov V. et al., GCN #27393). The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with the strongest peak at 2020-03-17 00:40:30.0 UT. The measured peak count rate associated with the burst is 507 +/- 32.0 cts/s above the background in the combined data of four quadrants, with a total of 1355 +/- 8.6 cts. The local mean background count rate was 528 +/- 1.0 cts/s. Using cumulative rates, we measure a T90 of 6.1 +/- 0.025 s. 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, ISAC, IUCAA, SAC and PRL. The Indian Space Research Organisation funded, managed and facilitated the project.