[vsnet-grb-info 27334] GRB 210207B: AstroSat CZTI detection

[GCN Circulars]

TITLE:   GCN CIRCULAR
NUMBER:  29437
SUBJECT: GRB 210207B: AstroSat CZTI detection
DATE:    21/02/09 11:42:14 GMT
FROM:    Gaurav Waratkar at IIT,Bombay  <gauravwaratkar at iitb.ac.in>

G. Waratkar (IITB), D. Nadella (NITK), 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 210207B, 
which was also detected by Swift (BAT - GCN #29420, #29435, XRT - 
#29422, #29427) Konus-Wind (GCN #29426), AGILE-MCAL (GCN #29428) and 
Insight-HXMT/HE (GCN #29434).

The source was clearly detected in the 20-200 keV energy range. The 
light curve showed multiple peaks of emission with the strongest peak at 
2021-02-07 21:52:49 UT in all four quadrants. The measured peak count 
rate associated with the burst is 517 (+52, -57) cts/s above the 
background in the combined data of four quadrants, with a total of 3408 
(+384, -451) cts. The local mean background count rate was 560 (+3, -3) 
cts/s. Using cumulative rates, we measure a T90 of 42 (+10, -2) s.

It was also clearly detected in the CsI anticoincidence (Veto) detector 
in the 100-500 keV energy range. The light curve showed multiple peaks 
of emission with the strongest peak at 2021-02-07 21:52:48 UT. The 
measured peak count rate is 994 (+88, -93) cts/s above the background in 
the combined Veto data of four quadrants, with a total of 6364 (+849, 
-894) cts. The local mean background count rate was 1931.8 (+5, -5) 
cts/s. We measure a T90 of 44 (+9, -4) 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.