TITLE: GCN CIRCULAR NUMBER: 20060 SUBJECT: GRB161015A: AstroSat CZTI detection DATE: 16/10/17 07:03:29 GMT FROM: Varun Bhalerao at IUCAA V. Kumar, V. Sharma, D. Bhattacharya and V. Bhalerao (IUCAA), A. R. Rao (TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: Analysis of AstroSat CZTI data showed clear detection of a bright GRB161015A (Fermi LAT detection: Masanori Ohno et al., GCN Circ. 20054) in the 40-200 keV energy range. The light curve shows a complex structure with peak at 17:03:08.04 UT after 1 second of the Fermi Trigger at 17:03:07.04 UT. The measured peak count rate is 660.0 counts/sec above the background in combined data of four quadrants, with a total of 2942.0 counts. The local mean background count rate was 320.0 counts/sec. Using cumulative rates, we measure a T90 of 22.0 secs. 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.