GCN Circular 35479

P. K. Navaneeth (IUCAA), 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 240102C which was also detected by Fermi (Trigger Num. 725857207), and Konus-IPN.

The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2024-01-02 03:00:04.50 UTC. The measured peak count rate associated with the burst is 170 (+35, -32) counts/s above the background in the combined data of all quadrants, with a total of 1021 (+191, -224) counts. The local mean background count rate was 336 (+2, -4) counts/s. Using cumulative rates, we measure a T90 of 10 (+4, -3) 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 2024-01-02 03:00:02.75 UTC. The measured peak count rate associated with the burst is 285 (+52, -45) counts/s above the background in the combined data of two quadrants (out of four), with a total of 2066 (+305, -324) counts. The local mean background count rate was 757 (+3, -4) counts/s. We measure a T90 of 19 (+2, -8) 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