TITLE:   GCN CIRCULAR
NUMBER:  29746
SUBJECT: GRB 210328A: AstroSat CZTI detection
DATE:    21/04/03 04:49:11 GMT
FROM:    Gaurav Waratkar at IIT Bombay  <gauravwaratkar24@gmail.com>

P.  Sawant (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), S. Gupta
(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 long GRB 210328A, which was also
detected by Fermi-GBM (GCN #29732, #29733) and GECAM-B (GCN #29737).

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
2021-03-28 20:45:21.5 UT. The measured peak count rate associated with the
burst is 338 (+48, -45) cts/s above the background in the combined data of
four quadrants, with a total of 4242 (+496, -511) cts. The local mean
background count rate was 528 (+2, -3) cts/s. Using cumulative rates, we
measure a T90 of 39 (+10, -13) 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 2021-03-28 20:45:18.1 UT. The measured
peak count rate is 296 (+85, -28) cts/s above the background in the
combined Veto data of four quadrants, with a total of 3378 (+447, -604)
cts. The local mean background count rate was 1740 (+6, -5) cts/s. We
measure a T90 of 18 (+3, -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.