TITLE:   GCN CIRCULAR
NUMBER:  28451
SUBJECT: GRB 200916B: AstroSat CZTI detection
DATE:    20/09/18 14:41:34 GMT
FROM:    Soumya Gupta at IUCAA/ASTROSAT  <soumya@iucaa>

S. Gupta, V. Sharma and D. Bhattacharya (IUCAA), V. Bhalerao (IIT-B), A. R. Rao (IUCAA/TIFR) and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration: 

Analysis of AstroSat CZTI data showed detection of a short GRB 200916B, which was also detected by IPN ( Ridnaia A. et al., GCN #28440). 

The source was clearly detected in the 40-200 keV energy range. The light curve showed a single peak of emission peaking at 2020-09-16 15:41:29.437 UT. The measured peak count rate associated with the burst is 143 +/- 23 cts/s above the background in the combined data of four quadrants, with a total of 230 +/- 2 cts. The local mean background count rate was 422 +/- 1 cts/s. Using cumulative rates, we measure a T90 of 1.7 s. 

It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed a single peak of emission peaking at 2020-09-16 15:41:28.00 UT. The measured peak count rate is 378 +/- 46 cts/s above the background in the combined Veto data of four quadrants, with a total of 727 +/- 5 cts. The local mean background count rate was 1739 +/- 2 cts/s. We measure a T90 of 1.7 s from the cumulative Veto light curve. 

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.