TITLE:   GCN CIRCULAR
NUMBER:  27864
SUBJECT: GRB 200530A: AstroSat CZTI detection
DATE:    20/05/30 11:18:25 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 the detection of a long GRB 200530A, which was also detected by Fermi GBM (GCN #27861) and Global MASTER-Net (Lipunov V. et al., GCN # 27862).

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 2020-05-30 00:44:20.150 UT. The measured peak count rate associated with the burst is 669 +/- 29 cts/s above the background in the combined data of four quadrants, with a total of 8172 +/- 74 cts. The local mean background count rate was 498 +/- 2 cts/s. Using cumulative rates, we measure a T90 of 20.98 +/- 0.08 s. In preliminary analysis, we find that 605 Compton events are associated with this event.

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 2020-05-30 00:44:19.000 UT. The measured peak count rate is 709 +/- 46 cts/s above the background in the combined Veto data of four quadrants, with a total of 5449 +/- 134 cts. The local mean background count rate was 1431 +/- 3 cts/s.  We measure a T90 of 20.87 +/- 0.31 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.