GCN Circular 33492

P K. Navaneeth (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 230320B which was 
also detected by Fermi GBM (TrigNum: 701039550), CALET (ID Num: 
1363381768) and GECAM (TrigNum: 163).

The source was clearly detected in the 20-200 keV energy range. The 
light curve peaks at 2023-03-20 21:12:27.50 UTC. The measured peak count 
rate associated with the burst is 415 (+48, -33) counts/s above the 
background in the combined data of three quadrants (out of four), with a 
total of 1976 (+332, -251) counts. The local mean background count rate 
was 360 (+2, -3) counts/s. Using cumulative rates, we measure a T90 of 
11.27 (+6, -4) s.

The source was also clearly detected in the CsI anticoincidence (Veto) 
detector in the 100-500 keV energy range. The light curve peaks at 
2023-03-20 21:12:26.59 UTC. The measured peak count rate associated with 
the burst is 377 (+80, -44) counts/s above the background in the 
combined data of all quadrants, with a total of 1527 (+371, -423) 
counts. The local mean background count rate was 1564 (+4, -4) counts/s. 
We measure a T90 of 12.92 (+8, -4) 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 [1]

Links:
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[1] http://astrosat.iucaa.in/czti/?q=grb