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GCN Circular 33479

Subject
GRB 230313A: AstroSat CZTI detection
Date
2023-03-15T03:17:07Z (2 years ago)
From
Gaurav Waratkar at IIT,Bombay <gauravwaratkar@iitb.ac.in>
A. Ahmad (IITB), G. Waratkar (IITB), P K. Navaneeth (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 GRB 230313A which was 
also detected by Fermi GBM (GCN Circ. 33467).

The source was faintly detected in the 20-200 keV energy range. The 
light curve peaks at 2023-03-13 11:38:43.9 UTC. The measured peak count 
rate associated with the burst is 211.1 (+167.6 -9.9) counts/s above the 
background in the combined data of three quadrants (out of four), with a 
total of 259 (+104 -110) counts. The local mean background count rate 
was 371.0 (+8.7 -8.6) counts/s. Using cumulative rates, we measure a T90 
of 3.68 (+0.61 -2.44) s.

It was also faintly detected in the CsI anticoincidence (Veto) detector 
in the 100-500 keV energy range. The light curve peaks at 2023-03-13 
11:38:43.2 UTC. The measured peak count rate is 270.4 (+59.6 -65.5) 
counts/s above the background in the combined Veto data of three 
quadrants (out of four), with a total of 463 (+172 -181) counts. The 
local mean background count rate was 1116.0 (+5.4 -6.4) counts/s. We 
measure a T90 of 4.28 (+1.18 -3.20) 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
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