TITLE:   GCN CIRCULAR
NUMBER:  25258
SUBJECT: GRB 190731A: AstroSat CZTI detection
DATE:    19/08/03 04:09:06 GMT
FROM:    Prachee Ghumatkar at IUCAA/AstroSat  <prachee@iucaa.in>

P. Ghumatkar, V. Sharma, D. Bhattacharya and A. Vibhute (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 long GRB 190731A, which was also detected by Fermi GBM (GCN #25240), Global MASTER-Net (Lipunov V. et al., GCN #25242), Fermi-LAT (Ohno M. et al., GCN #25244), Swift ToO (Evans P. A. et al., GCN #25245), CALET Gamma-Ray Burst Monitor detection (Asaoka Y. et al., GCN #25246), IPN Triangulation (Hurley K. et al., GCN #25250) and Swift-XRT (Osborne J.P. et al., GCN #25251).

The source was clearly detected in the 40-200 keV energy range. The light curve shows multiple pulses of emission with the strongest peak at 22:38:24.0 UT. The measured peak count rate associated with the burst is 2165 cts/s above the background in the combined data of four quadrants, with a total of 18049 cts. The local mean background count rate was 520 cts/s. Using cumulative rates, we measure a T90 of 20 s. In preliminary analysis, we find that 1455 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.

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.