TITLE:   GCN CIRCULAR
NUMBER:  32246
SUBJECT: GRB 220623A: AstroSat CZTI detection
DATE:    22/06/23 11:15:23 GMT
FROM:    Gaurav Waratkar at IIT,Bombay  <gauravwaratkar@iitb.ac.in>

R. Gopalakrishnan (IUCAA), V. Prasad (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 220623A which was 
also detected by Swift-BAT (Sbarufatti et al., GCN 32243), Swift-XRT 
(Kennea et al., GCN 32244) and INTEGRAL SPI-ACS (TrigNum: 9966).

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 
2022-06-23 07:04:14.500 UTC. The measured peak count rate associated 
with the burst is 127 (+38, -17) counts/s above the background in the 
combined data of three (out of four) quadrants, with a total of 738 
(+204, -207) counts. The local mean background count rate was 360 (+2, 
-2) counts/s. Using cumulative rates, we measure a T90 of 9 (+9, -2) 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 2022-06-23 07:04:13.771 UTC. The 
measured peak count rate is 570 (+74, -60) counts/s above the background 
in the combined Veto data of all quadrants, with a total of 2919 (+440, 
-459) counts. The local mean background count rate was 1502 (+5, -5) 
counts/s. We measure a T90 of 8 (+4, -1) 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.