GCN Circular 34524

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 230818B which was also detected by Konus-Wind (reported in GCN notices).

The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2023-08-18 10:12:55.5 UTC. The measured peak count rate associated with the burst is 139 (+41, -20) counts/s above the background in the combined data of all quadrants, with a total of 1336 (+411, -462) counts. The local mean background count rate was 423 (+3, -4) counts/s. Using cumulative rates, we measure a T90 of 20 (+8, -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 2023-08-18 10:12:54.3 UTC. The measured peak count rate associated with the burst is 379 (+74, -41) counts/s above the background in the combined data of all quadrants, with a total of 4772 (+696, -879) counts. The local mean background count rate was 1568 (+7, -8) counts/s. We measure a T90 of 26 (+2, -5) 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