TITLE:   GCN CIRCULAR
NUMBER:  35892
SUBJECT: GRB 240306A: AstroSat CZTI detection
DATE:    24/03/07 08:00:05 GMT
FROM:    Gaurav Waratkar at IIT Bombay <gauravwaratkar24@gmail.com>

J. Joshi (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-duration GRB 240306A which was also detected by Fermi-GBM (Fermi GBM team, GCN Circ. 35885), and Swift-BAT (Parsotan et al., GCN Circ. 35889).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2024-03-06 06:45:51.65 UTC. The measured peak count rate associated with the burst is 256 (+160, -4) counts/s above the background in the combined data of all quadrants, with a total of 633 (+225, -236) counts. The local mean background count rate was 301 (+7, -9) counts/s. We caution that there is a 0.3 s readout dead time in CZTI data during the burst which affects the calculated total count rate. Using cumulative rates, we measure a T90 of 7.1 (+1.6, -2.4) s. 

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