TITLE:   GCN CIRCULAR
NUMBER:  28526
SUBJECT: GRB 200928B: AstroSat CZTI detection
DATE:    20/09/29 08:30:54 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 long GRB 200928B, which was also detected by Fermi GBM (GCN #28521) and BALROG (Biltzinger B. et al., GCN #28522).

The source was clearly detected in the 40-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2020-09-28 13:14:43.203 UT. The measured peak count rate associated with the burst is 221 +/- 22 cts/s above the background in the combined data of four quadrants, with a total of 1755 +/- 19 cts. The local mean background count rate was 448 +/- 1 cts/s. Using cumulative rates, we measure a T90 of 15.20 +/- 0.02 s.

It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2020-09-28 13:14:44.792 UT. The measured peak count rate is 209 +/- 29 cts/s above the background in the combined Veto data of four quadrants, with a total of 1401 +/- 40 cts. The local mean background count rate was 1561 +/- 2  cts/s. We measure a T90 of 15.81 +/- 0.89 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.