TITLE: GCN CIRCULAR NUMBER: 19661 SUBJECT: GRB 160623A: Astrosat CZTI detection DATE: 16/07/06 06:58:47 GMT FROM: Varun Bhalerao at IUCAA V. Bhalerao (IUCAA), V. Kumar (IUCAA), D. Bhattacharya (IUCAA), A. R. Rao (TIFR), S. Vadawale (PRL) report on behalf of the Astrosat CZTI collaboration: Analysis of Astrosat data showed the detection of very bright GRB 160623A (Fermi-LAT detection: Vianello et al., GCN 19553, Mailyan et al., GCN 19555; Mingo et al. GCN 19558; Frederiks et al. GCN 19554) The source was clearly detected in the 40-200 keV energy range. The light curve shows a single peak at UT 04:59:45.0, 49.23 seconds before the fermi trigger At 05:00:34.23 (trigger 488350837 / 160623209). The peak count rate was 2940 counts/sec above the background (four quadrants summed together), with a total of 20385 counts. The local mean background count rate of 193.2 is counts/sec. Using cumulative rates, we measure a T90 of 14.2 sec. CZTI GRB detections are reported regularly on the payload site at http://astrosat.iucaa.in/czti/?q=node/9 . 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. [GCN OPS NOTE(07jul16): Per operator, the GRB name as corrected from 1600625 to 160625.]