//////////////////////////////////////////////////////////////////////// TITLE: GCN CIRCULAR NUMBER: 28354 SUBJECT: GRB200817B: AstroSat CZTI detection DATE: 20/09/03 09:58:27 GMT FROM: Varun Bhalerao at Indian Inst of Tech V. Shenoy (IITB), V. Bhalerao (IITB), S. Gupta, V. Sharma, A. Vibhute, D. Bhattacharya (IUCAA), A. R. Rao (TIFR), S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data showed the detection of a long GRB 200817B. The source was detected in the 20-200 keV energy range. The light curve showed multiple pulses of emission with the strongest peak at 2020-08-17 06:03:44 UT. The measured peak count rate associated with the burst is 453 cts/s above the background in the combined data of four quadrants, with a total of 3726 cts. The local mean background count rate was 488 cts/s. Using cumulative rates, we measure a T90 of 21.0 s. It was also detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. 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.