TITLE: GCN CIRCULAR NUMBER: 44197 SUBJECT: GRB 260402C: AstroSat CZTI detection of a long burst DATE: 26/04/03 07:19:42 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910@gmail.com> M. Tembhurnikar (IUCAA), Harsha K. H. (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 a long-duration GRB 260402C. The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve showed multiple peaks of emission with the strongest peak at 2026-04-02 13:13:05.78 UTC. The measured peak count rate associated with the burst is 254 (+34, -26) counts/s above the background in the combined data of three quadrants (out of four), with a total of 1786 (+230, -307) counts. The local mean background count rate was 210 (+2, -3) counts/s. Using cumulative rates, we measure a T90 of 27 (+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 showed multiple peaks of emission with the strongest peak at 2026-04-02 13:13:05.08 UTC. The measured peak count rate associated with the burst is 570 (+82, -42) counts/s above the background in the combined data of all quadrants, with a total of 3647 (+569, -635) counts. The local mean background count rate was 1405 (+6, -7) counts/s. We measure a T90 of 25 (+4, -1) 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 View this GCN Circular online at https://gcn.nasa.gov/circulars/44197. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...