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 a weak detection of a long GRB 200909A, which was also detected by Fermi GBM (GCN #28401), BALROG (Biltzinger B. et al., GCN #28402) and Global MASTER-Net (Lipunov V. et al., GCN #28403).
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 2020-09-09 04:01:27.86 UT. The measured peak count rate associated with the burst is 264 +/- 22 cts/s above the background in the combined data of four quadrants, with a total of 1437 +/- 20 cts. The local mean background count rate was 424 +/- 1 cts/s. Using cumulative rates, we measure a T90 of 21.68 +/- 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 2020-09-09 04:01:21.254 UT. The measured peak count rate is 354 +/- 45 cts/s above the background in the combined Veto data of four quadrants, with a total of 1126 +/- 32 cts. The local mean background count rate was 1744 +/- 1 cts/s. We measure a T90 of 21.12 +/- 0.01 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.