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GCN Circular 33686

Subject
GRB 230426A: AstroSat CZTI detection
Date
2023-04-27T05:36:14Z (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 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 230426A which was also detected by Fermi (Fermi GBM Team, GCN Circ. 33684Not found
 
 
).

The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2023-04-26 20:29:23.50 UTC. The measured peak count rate associated with the burst is 1773 (+77, -81) counts/s above the background in the combined data of all quadrants, with a total of 14876 (+653, -615) counts. The local mean background count rate was 454 (+2, -3) counts/s. Using cumulative rates, we measure a T90 of 23 (+3, -2) s. In the preliminary analysis, we find 1069 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 2023-04-26 20:29:23.50 UTC. The measured peak count rate associated with the burst is 1179 (+82, -77) counts/s above the background in the combined data of all quadrants, with a total of 8609 (+655, -665) counts. The local mean background count rate was 1491 (+4, -5) counts/s. We measure a T90 of 18 (+5, -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