GCN Circular 34505

P. K. Navaneeth (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao (IITB), D. Bhattacharya (Ashoka University/IUCAA), A. R. Rao (IUCAA/TIFR), and S. Vadawale (PRL) report on behalf of the AstroSat CZTI collaboration:

Analysis of AstroSat CZTI data with the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long GRB 230820A which was also detected by Konus Wind (reported through IPN_RAW notices).

The source was clearly detected in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2023-08-20 11:05:11.65 UTC. The measured peak count rate associated with the burst is 1594 (+233, -173) counts/s above the background in the combined data of all quadrants, with a total of 1625 (+217, -130) counts. The local mean background count rate was 457 (+7, -14) counts/s. Using cumulative rates, we measure a T90 of 4.9 (+0.2, -0.1) s.

The source 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 2023-08-20 11:05:12.25 UTC. The measured peak count rate associated with the burst is 1477 (+88, -95) counts/s above the background in the combined data of all quadrants, with a total of 4814 (+453, -495) counts. The local mean background count rate was 1440 (+7, -8) counts/s. We measure a T90 of 8.5 (+4.0, -3.0) s from the cumulative Veto light curve.

CZTI is built by a TIFR-led consortium of institutes across India, including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research Organisation funded, managed, and facilitated the project.

CZTI GRB detections are reported regularly on the payload site at: 
http://astrosat.iucaa.in/czti/?q=grb