GCN Circular 29074

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 201216C, 
which was also detected by Swift BAT (GCN #29061) and Fermi GBM (GCN 
#29063).

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 
2020-12-16 23:07:47.500 UT. The measured peak count rate associated with 
the burst is 1160 (+72, -40) cts/s above the background in the combined 
data of four quadrants, with a total of 18073 (+682, -728) cts. The 
local mean background count rate was 652 (+4, -4) cts/s. Using 
cumulative rates, we measure a T90 of 29 (+2, -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 2020-12-16 23:07:47.247 UT. The 
measured peak count rate is 1679 (+106, -78) cts/s above the background 
in the combined Veto data of four quadrants, with a total of 22904 
(+1443 -1654) cts. The local mean background count rate was 2400 (+7, 
-8) cts/s. We measure a T90 of 26 (+4, -2) 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.