GCN Circular 27766

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 200519A, which was also detected by Swift (Sbarufatti B. et al., GCN #27756), iTelescope (Kong A.et al., GCN # 27757), LCO (Strausbaugh R. et al., GCN # 27759), BOOTES-3/YA (Hu Y. et al., GCN # 27760), 1.3m DFOT (Kumar A. et al., GCN # 27764) and Global MASTER-Net (Lipunov V. et al., GCN # 27765).

The source was clearly detected in the 40-200 keV energy range. Of the ~80-second duration reported by Swift/BAT, CZTI detected only the brightest segment peaking at 2020-05-19 11:20:46.500 UT. The measured peak count rate associated with the burst is 983 +/- 39 cts/s above the background in the combined data of four quadrants, with a total of 3616 +/- 17 cts. The local mean background count rate was 519 +/- 1 cts/s. Using cumulative rates, we measure a T90 of 8.46 +/- 0.05 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 2020-05-19 11:20:46.000 UT. The measured peak count rate is 2339 +/- 62 cts/s above the background in the combined Veto data of four quadrants, with a total of 8499 +/- 21 cts. The local mean background count rate was 1541 +/- 1 cts/s.  We measure a T90 of 8.64 +/- 0.02 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.