V. Prasad (IUCAA), 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 CIFT framework (Sharma et al.,
2021, JApA, 42, 73) showed detection of a long GRB 211219A which was
also detected by Fermi (GCN 31265), MASTER-Net (Lipunov et al. GCN
31268), Swift/BAT-GUANO (Tohuvavohu et al., GCN 31269) and AGILE (Ursi
et al., GCN 31270).
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
2021-12-19 14:55:22.50 UT. The measured peak count rate associated with
the burst is 178 (+42, -26) cts/s above the background in the combined
data of two quadrants, with a total of 912 (+201, -218) cts. The local
mean background count rate was 382 (+2, -3) cts/s. Using cumulative
rates, we measure a T90 of 15 (+3, -8) s.
It was also clearly detected in the CsI anticoincidence (Veto) detector
in the 100-500 keV energy range. The light curve peaks at 2021-12-19
14:55:23.063 UT. The measured peak count rate is 740 (+72, -70) cts/s
above the background in the combined Veto data of four quadrants, with a
total of 3100 (+285, -308) cts. The local mean background count rate was
1243 (+4, -5) cts/s. We measure a T90 of 11.0 (+0.3, -5.2) 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.