GCN Circular 33575
Subject
GRB 230405B: AstroSat CZTI detection
Date
2023-04-06T07:26:20Z (a year ago)
From
Gaurav Waratkar at IIT,Bombay <gauravwaratkar@iitb.ac.in>
P K. Navaneeth (IUCAA), G. Waratkar (IITB), A. Vibhute (IUCAA), V.
Bhalerao (IITB), D. Bhattacharya (Ashoka University/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 the detection of a long GRB 230405B which was
also detected by Fermi (Fermi GBM Team, GCN 33570), and Swift (Page et
al., GCN 33571).
The source was clearly detected in the 20-200 keV energy range. The
light curve peaks at 2023-04-05 19:58:05.65 UTC. The measured peak count
rate associated with the burst is 894 (+200, -92) counts/s above the
background in the combined data of three quadrants (out of four), with a
total of 1098 (+189, -189) counts. The local mean background count rate
was 336 (+8, -10) counts/s. Using cumulative rates, we measure a T90 of
4.3 (+1.0, -1.7) s.
The source was also clearly detected in the CsI anticoincidence (Veto)
detector in the 100-500 keV energy range. The light curve peaks at
2023-04-05 19:58:05.12 UTC. The measured peak count rate associated with
the burst is 1564 (+88, -98) counts/s above the background in the
combined data of all quadrants, with a total of 3078 (+369, -404)
counts. The local mean background count rate was 1466 (+5, -6) counts/s.
We measure a T90 of 4.1 (+5.1, -1.5) s from the cumulative Veto light
curve.
CZTI is built by a TIFR-led consortium of institutes across India,
including VSSC, URSC, IUCAA, SAC, and PRL. The Indian Space Research
Organisation funded, managed, and facilitated the project.
CZTI GRB detections are reported regularly on the payload site at:
http://astrosat.iucaa.in/czti/?q=grb