[vsnet-grb-info 27307] GRB 210204A: AstroSat CZTI Detection
GCN Circulars
gcncirc at capella2.gsfc.nasa.gov
Sat Feb 6 19:47:41 JST 2021
TITLE: GCN CIRCULAR
NUMBER: 29410
SUBJECT: GRB 210204A: AstroSat CZTI Detection
DATE: 21/02/06 10:46:42 GMT
FROM: Gaurav Waratkar at IIT,Bombay <gauravwaratkar at iitb.ac.in>
G. Waratkar (IITB), V. Shenoy (IITB), A. Vibhute (IUCAA), S. Gupta
(IUCAA), P. Sawant (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,
2020, arxiv:2011.07067) showed detection of a bright long GRB 210204A,
which was also detected by Fermi-GBM (GCN #29390, #29393) and GECAM-B
(GCN #29392).
The source was clearly detected in the 20-200 keV energy range. The
light curve showed two isolated emission peaks with the stronger peak at
2021-02-04 06:32:45 UT in all four quadrants. The measured peak count
rate associated with the burst is 789 (+58, -61) cts/s above the
background in the combined data of four quadrants, with a total of 18141
(+1631, -1364) cts. The initial fainter peak contributed to about 6% of
the reported total counts. The local mean background count rate was 480
(+2, -3) cts/s. Using cumulative rates, we measure a T90 of 200 (+7,
-10) s.
It was also clearly detected in the CsI anticoincidence (Veto) detector
in the 100-500 keV energy range. The light curve showed two isolated
peaks of emission with the stronger peak at 2021-02-04 06:32:45 UT. The
initial fainter peak contributed less than 5% of total counts and hence
was excluded from the following analysis. The measured peak count rate
is 754 (+76, -80) cts/s above the background in the combined Veto data
of four quadrants, with a total of 15971 (+827, -996) cts. The local
mean background count rate was 1575 (+2, -3) cts/s. We measure a T90 of
57 (+7, -5) 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.
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