TITLE:   GCN CIRCULAR
NUMBER:  32186
SUBJECT: GRB 220609B: AstroSat CZTI detection
DATE:    22/06/10 04:31:26 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 220609B which was 
also detected by CALET GBM (Asaoka et al., GCN Circ. 32185).

The source was clearly detected in the 20-200 keV energy range. The 
light curve peaks at 2022-06-09 12:21:15.65 UTC. The measured peak count 
rate associated with the burst is 1230 (+239, -53) counts/s above the 
background in the combined data of four quadrants, with a total of 6095 
(+298, -291) counts. The local mean background count rate was 411 (+3, 
-6) counts/s. Using cumulative rates, we measure a T90 of 11 (+1, -1) s.

It was also clearly detected in the CsI anticoincidence (Veto) detector 
in the 100-500 keV energy range. The light curve peaks at 2022-06-09 
12:21:15.42 UTC. The measured peak count rate is 4988 (+127, -136) 
counts/s above the background in the combined Veto data of four 
quadrants, with a total of 24547 (+545, -597) counts. The local mean 
background count rate was 1421 (+5, -5) counts/s. We measure a T90 of 11 
(+2, -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.