GCN Circular 42098
Subject
GRB 251001A: AstroSat CZTI detection
Event
Date
2025-10-03T18:19:12Z (5 days ago)
From
Anuraag Arya at IIT Bombay <aryaanuraag910@gmail.com>
Via
Web form
Harsha K. H. (IUCAA), M. Tembhurnikar (IUCAA), S. Salunke (IUCAA), A. Arya (IITB), A. Goyal (IITB), 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 GRB 251001A which was also detected by Fermi/GBM (GCN Circ. 41993), Insight-HXMT (Wang et al., 42057). We detect only the second pulse as seen in the GBM lightcurve because the source is likely at a sky position where our effective area is low.
The source was detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-10-01 02:40:59.96 UTC. The measured peak count rate associated with the burst is 372 (+65, -75) counts/s above the background in the combined data of all four quadrants, with a total of 333 (+172, -206) counts. The local mean background count rate was 1380 (+11, -11) 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