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GCN Circular 31412

Subject
GRB 220107B: AstroSat CZTI detection
Date
2022-01-08T13:20:02Z (2 years ago)
From
Gaurav Waratkar at IIT,Bombay <gauravwaratkar@iitb.ac.in>
A. Suresh (IITB), 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 220107B, which was
also detected by Fermi-GBM (trigger 663274898/220107793), Fermi-LAT
(Axelsson et al., GCN 31409) and Swift-XRT (Gropp et al., GCN 31411). 

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
2022-01-07 19:01:45.50 UT. Quadrant B was noisy, and we exclude it from
further analysis. The measured peak count rate associated with the burst
is 372 (+44 -42) cts/s above the background in the combined data of
three quadrants (out of four), with a total of 2558 (+225 -239) cts. The
local mean background count rate was 382 (+2 -2) cts/s. Using cumulative
rates, we measure a T90 of 19 (+3 -1) 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 2022-01-07 19:01:35.775 UT. The
measured peak count rate is 826 (+81 -85) cts/s above the background in
the combined Veto data of four quadrants, with a total of 5424 (+496
-555) cts. The local mean background count rate was 1721 (+4 -5) cts/s.
We measure a T90 of 22 (+2 -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 [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
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