Skip to main content
New Swift-BAT/GUANO and IceCube Notice Types Available! See news and announcements

GCN Circular 33415

Subject
GRB 230307A: AstroSat CZTI detection
Date
2023-03-08T06:17:52Z (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 the extremely bright long 
GRB 230307A which was also detected by Fermi-GBM (Fermi GBM team, GCN 
33405), GECAM (Xiong et al., GCN 33406), Solar Orbiter STIX (Xiao et 
al., GCN 33410), AGILE/MCAL (Casentini et al., GCN 33412) and IPN 
(Kozyrev et al., GCN 33413).

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 
2023-03-07 15:44:10.0 UTC. The measured peak count rate associated with 
the burst is 4041 (+33, -37) counts/s above the background in the 
combined data of all quadrants, with a total of 90900 (+758, -850) 
counts. The local mean background count rate was 453 (+1, -1) counts/s. 
Using cumulative rates, we measure a T90 of 33 (+1, -1) s. In the 
preliminary analysis, we find 5484 Compton events associated with this 
event.

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 2023-03-07 15:44:15.17 UTC. The 
measured peak count rate is 276156 (+268, -300) counts/s above the 
background in the combined Veto data of all quadrants, with a total of 
5571313 (+4953, -6044) counts. The local mean background count rate was 
14750 (+7, -6) counts/s. We measure a T90 of 40 (+0.2, -0.2) 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
Looking for U.S. government information and services? Visit USA.gov