GCN Circular 31178
Subject
GRB 211204C: AstroSat CZTI detection
Event
Date
2021-12-07T06:17:15Z (4 years ago)
From
Gaurav Waratkar at IIT,Bombay <gauravwaratkar@iitb.ac.in>
V. Prasad (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V. Bhalerao
(IITB), D. Bhattacharya (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 detection of the long GRB 211204C, which was
also detected by Fermi (GCN 31171), GECAM (Zhang et al., GCN 31173) and
Swift/BAT-GUANO (DeLaunay et al., GCN 31174) with IPN triangulation
reported (GCN 31177).
The source was clearly detected in the 20-200 keV energy range. The
light curve peaks at 2021-12-04 21:37:06.50 UT. The measured peak count
rate associated with the burst is 426 (+57, -23) cts/s above the
background in the combined data of two quadrants, with a total of 3173
(+195, -220) cts. The local mean background count rate was 500 (+2, -2)
cts/s. Using cumulative rates, we measure a T90 of 13 (+2, -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 2021-12-04
21:37:04.16 UT. The measured peak count rate is 592 (+80, -46) cts/s
above the background in the combined Veto data of four quadrants, with a
total of 4150 (+285, -354) cts. The local mean background count rate was
1677 (+4, -4) cts/s. We measure a T90 of 10 (+1, -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, ISAC, IUCAA, SAC,
and PRL. The Indian Space Research Organisation funded, managed, and
facilitated the project.