GCN Circular 35799

J. Joshi (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 240225C which was also detected by Calet (Trigger Num. 1392873321), INTEGRAL/SPI-ACS (Trigger Num. 10590), and Konus-WIND (IPN RAW notices).

The source was detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2024-02-25 05:19:38.80 UTC. The measured peak count rate associated with the burst is 289 (+71, -45) counts/s above the background in the combined data of all quadrants, with a total of 1297 (+320, -349) counts. The local mean background count rate was 1387 (+7, -7) counts/s. We measure a T90 of 6.7 (+2.6, -1.6) 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