GCN Circular 35190

G. Waratkar (IITB), P. K. Navaneeth (IUCAA),  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-duration GRB 231125A. We also inspected  INTEGRAL/SPI-ACS data, and see a detection there.

The source was clearly detected in the 20-200 keV energy range. The light curve peaks at 2023-11-25 17:47:20.75 UTC. The measured peak count rate associated with the burst is 1641.9 (+219.7, -187.4) counts/s above the background in the combined data of three quadrants (out of four), with a total of 901 (+67, -66) counts. The local mean background count rate was 255.6 (+3.7, -6.9) counts/s. Using cumulative rates, we measure a T90 of 1.09 (+0.31, -0.23) 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 2023-11-25 17:47:20.72 UTC. The measured peak count rate is 1315.6 (+87.4, -93.6) counts/s above the background in the combined Veto data of all quadrants, with a total of 2706 (+219, -253) counts. The local mean background count rate was 1618.4 (+11.8, -11.9) 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