GCN Circular 34447

B. Pari (IITB), 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 230815B which was also detected by GECAM-B (TrigNum 211).

The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2023-08-15 16:08:28.5 UTC. The measured peak count rate associated with the burst is 271.4 (+40.4, -41.4) counts/s above the background in the combined data of all quadrants, with a total of 2148 (+375, -381) counts. The local mean background count rate was 335.7 (+2.4, -3.0) counts/s. Using cumulative rates, we measure a T90 of 33.2 (+8.9, -11.6) s. 

The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2023-08-15 16:08:27.3 UTC. The measured peak count rate associated with the burst is 725.5 (+75.8, -66.6) counts/s above the background in the combined data of all quadrants, with a total of 9598 (+1234, -1292) counts. The local mean background count rate was 1481.2 (+5.7, -6.9) counts/s. We measure a T90 of 43.5 (+8.7, -12.6) 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