TITLE: GCN CIRCULAR NUMBER: 30378 SUBJECT: GRB 210704A: AstroSat CZTI detection DATE: 21/07/05 15:15:59 GMT FROM: Gaurav Waratkar at IIT,Bombay V. Prasad (IUCAA), P. Sawant (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al, 2020, arxiv:2011.07067) showed detection of a short GRB 210704A, which was also detected by Fermi - GBM (Trigger 647120009 / GRB210704815), Fermi-LAT (GCN 30375), and AGILE/MCAL (GCN 30372). The source was clearly detected in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2021-07-04 19:33:24.4 UT. The measured peak count rate associated with the burst is 706 (+179, -132) cts/s above the background in the combined data of four quadrants, with a total of 359 (+106, -109) cts. The local mean background count rate was 489 (+6, -8) cts/s. Using cumulative rates, we measure a T90 of 1.0 (+0.4, -0.4) s. It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. In one-second bins, the measured peak count rate associated with the burst is 1417.7 (+89.9 -97.4) cts/s above the background in the combined data of four quadrants, with a total of 2430 (+327 -361) cts. The local mean background count rate was 1743.4 (+4.2 -4.2) cts/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.