GCN Circular 33482

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 230304D which was 
also detected by Fermi - GBM (Trigger Number - 699634754).

The source was clearly detected in the 20-200 keV energy range. The 
light curve showed multiple peaks of emission with the strongest peak at 
2023-03-04 14:59:21.50 UTC. The measured peak count rate associated with 
the burst is 313 (+45, -41) counts/s above the background in the 
combined data of all quadrants, with a total of 2489 (+402, -322) 
counts. The local mean background count rate was 443 (+2, -4) counts/s. 
Using cumulative rates, we measure a T90 of 25.52 (+5, -2) s.

The source 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 2023-03-04 
14:59:20.91 UTC. The measured peak count rate associated with the burst 
is 390 (+67, -68) counts/s above the background in the combined data of 
all quadrants, with a total of 2433 (+610, -813) counts. The local mean 
background count rate was 1355 (+5, -5) counts/s. We measure a T90 of 
25.84 (+11, -17) 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