TITLE: GCN CIRCULAR NUMBER: 24121 SUBJECT: GRB 190407B: AstroSat CZTI detection DATE: 19/04/15 02:07:35 GMT FROM: Vidushi Sharma at IUCAA V. Sharma, D. Bhattacharya, A. Vibhute and T. Khanam (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 190407B, which was also detected by Fermi/GBM (Biltzinger B. et al., GCN # 24059). The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple peaks of emission with strongest peak at 18:54:42.500 UT. The measured peak count rate associated with the burst is 662 cts/s above the background in the combined data of four quadrants, with a total of 1147 cts. The local mean background count rate was 638 cts/s. Using cumulative rates, we measure a T90 of 2.3 s. It was also clearly 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.