GCN Circular 32853
Subject
GRB 221025A: AstroSat CZTI detection
Date
2022-10-26T13:42:23Z (2 years ago)
From
Gaurav Waratkar at IIT,Bombay <gauravwaratkar@iitb.ac.in>
R. Gopalakrishnan (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 short GRB 221025A which
was also detected by Fermi-GBM (Wood et al,. GCN 32851) and Fermi-LAT
(Arimoto et al,. GCN 32843).
The source was clearly detected in the 20-200 keV energy range. The
light curve peaks at 2022-10-25 00:58:18.6 UTC. The measured peak count
rate associated with the burst is 904 (+212, -102) counts/s above the
background in the combined data of all quadrants, with a total of 313
(+62, -63) counts. The local mean background count rate was 435 (+8,
-12) counts/s. Using cumulative rates, we measure a T90 of 0.45 (+0.6,
-0.2) s.
It was also detected in the CsI anticoincidence (Veto) detector in the
100-500 keV energy range. Due to the intrinsic 1 s binning of veto data,
we cannot reliably estimate a T90 from it.
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.