GCN Circular 33399

P K. Navaneeth (IUCAA), R. Gopalakrishnan (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 230304A which was 
also detected by Fermi GBM (GCN Circ. 33395
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 ).

The source was detected in the 20-200 keV energy range. The light curve 
showed multiple peaks of emission with the strongest peak at 2023-03-04 
06:21:01.35 UTC. The measured peak count rate associated with the burst 
is 292 (+147, -18) counts/s above the background in the combined data of 
three quadrants (out of four), with a total of 577 (+223, -214) counts. 
The local mean background count rate was 325 (+4, -6) counts/s. Using 
cumulative rates, we measure a T90 of 9.73 (+3, -4) s.

It was also detected in the CsI anticoincidence (Veto) detector in the 
100-500 keV energy range. The light curve peaks at 2023-03-04 06:21:00.9 
UTC. The measured peak count rate is 927 (+77, -84) counts/s above the 
background in the combined Veto data of all quadrants, with a total of 
5710 (+511, -579) counts. The local mean background count rate was 1423 
(+5, -6) counts/s. We measure a T90 of 10.23 (+4, -2) s from the 
cumulative Veto light curve.

CZTI GRB detections are reported regularly on the payload site at 
http://astrosat.iucaa.in/czti/?q=grb. 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.