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GCN Circular 31863

Subject
GRB 220408B: AstroSat CZTI detection
Date
2022-04-09T11:38:11Z (2 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 220408B which was
also detected by Fermi-GBM (GCN 31854).

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
2022-04-08 07:28:08.50 UT. The measured peak count rate associated with
the burst is 1181 (+79, -36) counts/s above the background in the
combined data of all four quadrants, with a total of 12408 (+531, -419)
counts. The local mean background count rate was 516 (+2, -4) counts/s.
Using cumulative rates, we measure a T90 of  25 (+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 2022-04-08 07:28:08.19 UT. The
measured peak count rate is 1215 (+93, -70) counts/s  above the
background in the combined Veto data of four quadrants, with a total of
10873 (+743, -663) counts. The local mean background count rate was 1882
(+4, -5) counts/s. We measure a T90 of 24 (+2, -6) 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:
------
[1] http://astrosat.iucaa.in/czti/?q=grb
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