GCN Circular 42542

Subject

GRB 251102A: AstroSat CZTI detection

Event

GRB 251102A

Date

2025-11-03T09:34:19Z (2 days ago)

From

Anuraag Arya at IIT Bombay <aryaanuraag910@gmail.com>

Via

Web form

M. Tembhurnikar (IUCAA), S. Salunke (IUCAA), Harsha K. H. (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 a long GRB 251102A which was also detected by Fermi GBM (Fermi GBM Team, GCN Circ. 42531Loading...
 
 ) and Konus-Wind (IPN notices) .

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2025-11-02 02:04:02.50 UTC. The measured peak count rate associated with the burst is 138 (+36, -15) counts/s above the background in the combined data of all quadrants, with a total of 1258 (+189, -199) counts. The local mean background count rate was 275 (+3, -4) counts/s. Using cumulative rates, we measure a T90 of 16.2 (+1.0, -0.9) s. 

The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-11-02 02:03:58.03 UTC. The measured peak count rate associated with the burst is 164 (+71, -18) counts/s above the background in the combined data of all quadrants, with a total of 1518 (+313, -350) counts. The local mean background count rate was 1256 (+5, -5) counts/s. We measure a T90 of 17.0 (+1.7, -2.0) 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