TITLE: GCN CIRCULAR NUMBER: 24538 SUBJECT: GRB 190510B: AstroSat CZTI detection DATE: 19/05/14 12:45:27 GMT FROM: Prachee Ghumatkar at IUCAA/AstroSat P. Ghumatkar, V. Sharma, T. Khanam, D. Bhattacharya and A. Vibhute (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 190510B, which was also detected by Global-MASTER Net (Lipunov V. et al, GCN #24439). The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 02:52:21.5 UT. The measured peak count rate associated with the burst is 487 cts/s above the background in the combined data of four quadrants, with a total of 185 cts. The local mean background count rate was 103 cts/s. Using cumulative rates, we measure a T90 of 19.9 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.