GCN Circular 42740
Subject
GRB 251117A: AstroSat CZTI detection
Event
Date
2025-11-18T16:09:35Z (3 days ago)
From
Anuraag Arya at IIT Bombay <aryaanuraag910@gmail.com>
Via
Web form
A. Arya (IITB), A. Goyal (IITB), S. Salunke (IUCAA), M. Tembhurnikar (IUCAA), Harsha K. H. (IUCAA), G. Waratkar (Caltech/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 short GRB 251117A which was also detected by Fermi GBM (Fermi GBM Team, GCN Circ. 42719), Fermi LAT (Airasca et. al., GCN Circ. 42729), SVOM/GRM (Wang et. al., GCN Circ. 42731), and Swift BAT-GUANO (DeLaunay et. al., GCN Circ. 42732).
The source was clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-11-17 12:19:52.47 UTC. The measured peak count rate associated with the burst is 424 (+67, -72) counts/s above the background in the combined data of all quadrants, with a total of 561 (+156, -178) counts. The local mean background count rate was 1268 (+11, -12) counts/s.
Due to the intrinsic 1 s binning of veto data, we cannot reliably estimate a T90 from it.
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