[vsnet-grb-info 27239] GRB 210116A: AstroSat CZTI detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29342
SUBJECT: GRB 210116A: AstroSat CZTI detection
DATE:    21/01/22 03:24:25 GMT
FROM:    Gaurav Waratkar at IIT Bombay  <gauravwaratkar24 at gmail.com>

D. Nadella (NITK), G. Waratkar (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 210116A, which was
also detected by AstroSat LAXPC (GCN #29340).

The source was clearly detected in the 20-200 keV energy range. The light
curve showed a single strong peak at 2021-01-16 05:53:37.500 UT, in all
four quadrants of CZTI. Quadrant D was noisy, and we exclude it from
further analysis. The measured peak count rate associated with the burst is
781 (+54, -60) cts/s above the background in the combined data of three
quadrants (out of four), with a total of 3156 (+232, -222) cts. The local
mean background count rate was 395 (+3, -3) cts/s. Using cumulative rates,
we measure a T90 of 9.5 (+4.1, -1.8) s.

It was also clearly detected in the CsI anticoincidence (Veto) detector in
the 100-500 keV energy range. The light curve showed a single strong peak
of emission in all four quadrants, with the strongest peak consistent with
the above timing. The measured peak count rate is 3039 (+131, -62) cts/s
above the background in the combined Veto data of four quadrants, with a
total of 13614 (+475, -578) cts. The local mean background count rate was
1842 (+6, -6) cts/s. We measure a T90 of 8.8 (+1.7, -1.0) 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.