TITLE:   GCN CIRCULAR
NUMBER:  36996
SUBJECT: GRB 240801B: AstroSat CZTI detection of a bright long burst
DATE:    24/08/01 10:32:32 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>

A. Dasgupta (BITS Pilani, Hyderabad), S. Srijan (IITB), G. Waratkar (IITB), M. Tembhurnikar (IUCAA), J. Joshi (IUCAA), 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-duration GRB 240801B which was also detected by Fermi/GBM (Trigger 744179961).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2024-08-01 04:39:49.5 UTC. The measured peak count rate associated with the burst is 1206 (+62, -67) counts/s above the background in the combined data of three quadrants (out of four), with a total of 8862 (+301, -352) counts. The fourth quadrant has data quality issues and is excluded from the analysis. The local mean background count rate was 263 (+3, -4) counts/s. Using cumulative rates, we measure a T90 of 15 (+1, -1) s.

It 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 2024-08-01 04:39:48.3 UTC. The measured peak count rate is 2215 (+94, -84) counts/s above the background in the combined Veto data of all quadrants, with a total of 17867 (+476, -714) counts. The local mean background count rate was 1405 (+7, -6) counts/s. We measure a T90 of 15 (+1, -1) 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