GCN Circular 29437

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.