TITLE:   GCN CIRCULAR
NUMBER:  43919
SUBJECT: GRB 260303B: AstroSat CZTI detection
DATE:    26/03/04 19:43:04 GMT
FROM:    Anuraag Arya at IIT Bombay <aryaanuraag910@gmail.com>

M. Tembhurnikar (IUCAA), Harsha K. H. (IUCAA), S. Salunke (IUCAA), A. Arya (IITB), A. Goyal (IITB), G. Waratkar (Caltech/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 260303B which was also detected by Fermi GBM (Fermi GBM Team., GCN Circ. 43907), and NuSTAR (Waratkar et. al. , GCN Circ. 43914).

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2026-03-03 13:24:23.50 UTC. The measured peak count rate associated with the burst is 59 (+29, -5) counts/s above the background in the combined data of two quadrants (out of four), with a total of 504 (+69, -193) counts. The local mean background count rate was 167 (+1, -5) counts/s. We measure a T90 of 11 (+1, -3) s.

The source was also faintly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range.

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