TITLE: GCN CIRCULAR NUMBER: 43918 SUBJECT: GRB 260304A: AstroSat CZTI detection of a long burst DATE: 26/03/04 18:56:56 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910@gmail.com> A. Arya (IITB), A. Goyal (IITB), M. Tembhurnikar (IUCAA), Harsha K. H. (IUCAA), S. Salunke (IUCAA), 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 260304A which was also detected by Konus-Wind (Priv. Comm. with T0 at 07:24:53.608 UT). 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 2026-03-04 07:25:02.120 UTC. The measured peak count rate associated with the burst is 121 (+29, -16) counts/s above the background in the combined data of two quadrants (out of four), with a total of 1569 (+602, -342) counts. The local mean background count rate was 142 (+2, -3) counts/s. Using cumulative rates, we measure a T90 of 32 (+23, -9) 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 2026-03-04 07:24:50.186 UTC. The measured peak count rate associated with the burst is 298 (+72, -28) counts/s above the background in the combined data of all quadrants, with a total of 2770 (+533, -517) counts. The local mean background count rate was 1221 (+5, -4) counts/s. We measure a T90 of 31 (+3, -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 View this GCN Circular online at https://gcn.nasa.gov/circulars/43918. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...