GCN Circular 32364

A. Suresh (IITB), 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 220707A. It was 
also reported by INTEGRAL (Notice 9976,0).

The source was clearly detected in the 20-200 keV energy range. The 
light curve peaks at 2022-07-07 20:37:31.0 UTC. The measured peak count 
rate associated with the burst is 73 (+10 -9) counts/s above the 
background in the combined data of three quadrants, with a total of 3687 
(+409 -429) counts. The local mean background count rate was 332 (+1 -1) 
counts/s. Using cumulative rates, we measure a T90 of 75 (+11 -11) s.

It 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 2022-07-07 20:37:29.6 UTC. The 
measured peak count rate is 380 (+82 -10) counts/s above the background 
in the combined Veto data of all quadrants, with a total of 15340 (+1048 
-1023)  counts. The local mean background count rate was 1343 (+3 -4) 
counts/s. We measure a T90 of 81 (+7 -6) 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.