TITLE: GCN CIRCULAR NUMBER: 44885 SUBJECT: GRB 260604C: AstroSat CZTI detection DATE: 26/06/09 13:26:28 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910@gmail.com> A. Arya (IITB), A. Goyal (IITB), 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 GRB 260604C which was also detected by Fermi/GBM (Fermi GBM team, GCN Circ. 44822) and SVOM/ECLAIRs (D. Gotz et.al., GCN Circ. 44823). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2026-06-04 20:18:49 UTC. The measured peak count rate associated with the burst is 1274 (+126, -136) counts/s above the background in the combined data of all quadrants, with a total of 1904 (+116, -105) counts. The local mean background count rate was 282 (+4, -7) counts/s. Using cumulative rates, we measure a T90 of 2.7 (+0.5, -0.2) 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 2026-06-04 20:18:48 UTC. The measured peak count rate associated with the burst is 3712 (+112, -126) counts/s above the background in the combined data of all quadrants, with a total of 8150 (+207, -252) counts. The local mean background count rate was 1332 (+7, -6) counts/s. We measure a T90 of 3.3 (+0.2, -0.1) 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 data products like interactive and downloadable light curves for this GRB can be found at: https://astrosat.iucaa.in/cift/cift_products/ET20260604T201844/ET20260604T20... 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/44885. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...