R. Gopalakrishnan (IUCAA), V. Prasad (IUCAA), A. Suresh (IITB), G.
Waratkar (IITB), A. Vibhute (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 ML pipeline (Abraham et al.,
2021, MNRAS, 504, 3084) and the CIFT framework (Sharma et al., 2021,
JApA, 42, 73) showed detection of a bright long GRB 220320A which was
also detected by IPN (contributed by Konus-Wind at GCN Notices), and
Fermi - GBM (Trigger - 669443999).
The source was clearly detected in the 20-200 keV energy range. The
light curve peaks at 2022-03-20 04:39:59.25 UT. The measured peak count
rate associated with the burst is 2398 (+336, -71) counts/s above the
background in the combined data of four quadrants, with a total of 5427
(+307, -331) counts. The local mean background count rate was 507 (+5,
-9) counts/s. Using cumulative rates, we measure a T90 of 11 (+1, -1) s.
It was also clearly detected in the CsI anticoincidence (Veto) detector
in the 100-500 keV energy range. The light curve showed a peak at
2022-03-20 04:39:59.13 UT. The measured peak count rate is 3438 (+112,
-122) counts/s above the background in the combined Veto data of four
quadrants, with a total of 10543 (+502, -570) counts. The local mean
background count rate was 1529 (+5, -5) counts/s. We measure a T90 of 16
(+3, -3) 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.