GCN Circular 32549
Subject
GRB 220912A: AstroSat CZTI detection
Date
2022-09-12T18:06:24Z (3 years ago)
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 a weak detection of a long GRB 220912A which
was also detected by Fermi GBM (GCN 32546).
The source was clearly detected in the 20-200 keV energy range. The
light curve peaks at 2022-09-12 00:50:39.3 UTC. The measured peak count
rate associated with the burst is 294 (+173, -15) counts/s above the
background in the combined data of all quadrants, with a total of 1224
(+364, -386) counts. The local mean background count rate was 444 (+3,
-4) counts/s. Using cumulative rates, we measure a T90 of 26 (+7, -7) s.
It was also detected in the CsI anticoincidence (Veto) detector in the
100-500 keV energy range. The light curve peaks at 2022-09-12 00:50:25.0
UTC. The measured peak count rate is 188 (+76, -25) counts/s above the
background in the combined Veto data of all quadrants, with a total of
1476 (+545, -575) counts. The local mean background count rate was 1458
(+3, -4) counts/s. We measure a T90 of 24 (+14, -12) 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.