GCN Circular 31879
Subject
GRB 220411A: AstroSat CZTI detection
Date
2022-04-12T04:22:16Z (3 years ago)
From
Gaurav Waratkar at IIT,Bombay <gauravwaratkar@iitb.ac.in>
R. Gopalakrishnan (IUCAA), 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 220411A which was
also detected by Fermi - GBM (Trigger No. 220411306, GCN 31871) with
BALROG localisation reported (Kunzweiler et al., GCN 31872).
The source was clearly detected in the 20-200 keV energy range in three
quadrants (out of four). Two quadrants were noisy and we exclude them in
further analysis. The light curve peaked at 2022-04-11 07:20:02.25 UT.
The measured peak count rate associated with the burst is 337 (+151,
-22) counts/s above the background in the combined data of two
quadrants, with a total of 1155 (+298, -200) counts. The local mean
background count rate was 254 (+4, -5) counts/s. Using cumulative rates,
we measure a T90 of 19 (+1, -2) s.
It was also clearly detected in the CsI anticoincidence (Veto) detector
in the 100-500 keV energy range. The light curve showed a single peak of
emission at 2022-04-11 07:20:01.00 UT. The measured peak count rate is
499 (+73, -77) counts/s above the background in the combined Veto data
of four quadrants, with a total of 2897 (+734, -604) counts. The local
mean background count rate was 1722 (+3, -5) counts/s. We measure a T90
of 26 (+13, -10) 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 [1]. 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.
Links:
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[1] http://astrosat.iucaa.in/czti/?q=grb