GCN Circular 41200
Subject
GRB 250725A: AstroSat CZTI detection
Event
Date
2025-07-30T10:10:49Z (a month ago)
From
Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in>
Via
Web form
M. Tembhurnikar (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-duration GRB 250725A which was also detected by Fermi/GBM (Fermi GBM Team, GCN Circ. 41150), Swift/BAT (Evans et. al., GCN Circ. 41152), Konus/Wind (Frederiks et. al., GCN Circ. 41166), and SVOM/GRM (Wang et. al., GCN Circ. 41164).
The source was detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve contained two peaks with the strongest peak at 2025-07-25 01:51:36.83 UTC. The measured peak count rate associated with the burst is 500 (+81, -28) counts/s above the background in the combined data of all quadrants, with a total of 3013 (+264, -366) counts. The local mean background count rate was 1367 (+9, -7) counts/s. We measure a T90 of 10.0 (+0.6, -1.3) s from the cumulative Veto light curve.
The source was also faintly detected in the CZT detectors in the 20-200 keV energy range.
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