GCN Circular 26129

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

Analysis of AstroSat CZTI data showed the detection of a GRB 191031D, which was also detected by Fermi GBM Real-time Localization (GCN #26111), Swift (D'Elia et al., GCN #26112), Swift-XRT (Osborne et al., GCN #26117), Fermi GBM (Mailyan et al., GCN #26118), VLA (Laskar T. et al., GCN #26120), RATIR (Butler N. et al., GCN #26121), COATLI (Watson A. M. et al., GCN #26122), AGILE/MCAL (Ursi A. et al., GCN #26123), MITSuME Akeno (Ogawa F. et al., GCN #26125) and Konus-Wind (Frederiks D. et al., GCN #26126).

The source was clearly detected in the 40-200 keV energy range. The light curve showed single pulse of emission peaking at 2019-10-31 21:23:31.0 UT. The measured peak count rate associated with the burst is 628 cts/s above the background in the combined data of four quadrants, with a total of 393 cts. The local mean background count rate was 556 cts/s. Using cumulative rates, we measure a T90 of 0.35 s.

It was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.

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.