TITLE:   GCN CIRCULAR
NUMBER:  32316
SUBJECT: GRB 220627A: AstroSat CZTI detection
DATE:    22/07/02 11:42:11 GMT
FROM:    Gaurav Waratkar at IIT,Bombay  <gauravwaratkar@iitb.ac.in>

A. Suresh (IITB), G. Waratkar (IITB), R. Gopalakrishnan (IUCAA), V. 
Prasad (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 the long (or possibly 
lensed) GRB 220627A which was also detected by Fermi GBM (Fermi GBM 
team, GCN 32278; Roberts et al., GCN 32288), Fermi-LAT (Lalla et al., 
GCN 32283), Swift-BAT-GUANO (Raman et al., GCN 32287), Konus-Wind 
(Frederiks et al., GCN 32295), and Swift-XRT (Gropp et al. GCN 32302).

AstroSat CZTI was in the South Atlantic Anomaly (SAA) region during the 
first burst episode. About 1000s after the first burst, CZTI detected 
the second burst episode that was also reported by Fermi-GBM (GCN 
32288), and Konus-Wind (GCN 32295). This burst was clearly detected in 
the 20-200 keV energy range. The light curve peaks at 2022-06-27 
21:38:49.500 UTC. The measured peak count rate associated with the burst 
is 233 (+43, -41) counts/s above the background in the combined data of 
all four quadrants, with a total of 2707 (+454, -447) counts. The local 
mean background count rate was 500 (+3, -4) counts/s. Using cumulative 
rates, we measure a T90 of 43 (+2, -12) s.

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.