GCN Circular 33562
Subject
GRB 230402A: AstroSat CZTI detection
Date
2023-04-04T14:11:20Z (2 years 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 ML pipeline (Abraham et al.,
2021, MNRAS, 504, 3084) and the CIFT framework (Sharma et al., 2021,
JApA, 42, 73) showed the detection of a bright long GRB 230402A which
was also detected by Fermi (Fermi GBM Team, GCN 33553), and AGILE
(Casentini et al., GCN 33555).
The source was clearly detected in the 20-200 keV energy range. The
light curve peaks at 2023-04-02 07:32:36.5 UTC. The measured peak count
rate associated with the burst is 517 (+50, -55) counts/s above the
background in the combined data of all quadrants, with a total of 4283
(+374, -394) counts. The local mean background count rate was 456 (+3,
-4) counts/s. Using cumulative rates, we measure a T90 of 37 (+3, -5) s.
In the preliminary analysis, we find 588 Compton events associated with
this event.
The source was also clearly detected in the CsI anticoincidence (Veto)
detector in the 100-500 keV energy range. The light curve peaks at
2023-04-02 07:32:36.1 UTC. The measured peak count rate associated with
the burst is 692 (+67, -76) counts/s above the background in the
combined data of three quadrants (out of four), with a total of 5504
(+695, -805) counts. The local mean background count rate was 1185 (+2,
-2) counts/s. We measure a T90 of 37 (+21, -9) 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