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 211219B which was
also detected by Fermi-GBM (GCN 31267).
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 21:49:45.50 UT. The measured peak count rate associated with
the burst is 95 (+38, -18) cts/s above the background in the combined
data of two quadrants, with a total of 573 (+196, -205) cts. The local
mean background count rate was 398 (+2, -2) cts/s. Using cumulative
rates, we measure a T90 of 14 (+6, -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
21:49:45.056 UT. The measured peak count rate is 280 (+63, -50) cts/s
above the background in the combined Veto data of four quadrants, with a
total of 1460 (+257, -400) cts. The local mean background count rate was
1339 (+5, -3) cts/s. We measure a T90 of 8 (+5, -2) s from the
cumulative Veto light curve.
We also detected another fainter burst, likely from the same source,
that lasted for around 6 s in the CsI anticoincidence (Veto) detector
about 70 s after the primary burst.
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.