TITLE: GCN CIRCULAR NUMBER: 43677 SUBJECT: GRB 260208B: AstroSat CZTI detection of a bright long burst DATE: 26/02/10 02:01:04 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910@gmail.com> Harsha K. H. (IUCAA), M. Tembhurnikar (IUCAA), S. Salunke (IUCAA), U. Pathak (IITB), 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 ML pipeline (Abraham et al., 2021, MNRAS, 504, 3084) and the CIFT framework (Sharma et al., 2021, JApA, 42, 73) showed the detection of a long, bright GRB 260208B which was also detected by Fermi/GBM (Fermi GBM Team, GCN Circ. 43638), Fermi/LAT (F. Longo et al., GCN Circ. 43647), and SVOM/GRM (SVOM GRM Team, GCN Circ. 43650). We also see a relatively faint burst episode about 100 s after the initial bright burst in both CZT & CsI detectors. 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 2026-02-08 09:52:59.50 UTC. The measured peak count rate associated with the burst is 1334 (+64, -68) counts/s above the background in the combined data of all quadrants, with a total of 14112 (+381, -416) counts. The local mean background count rate was 272 (+2, -3) counts/s. Using cumulative rates, we measure a T90 of 24 (+6, -2) s. In the preliminary analysis, we find 2125 Compton events associated with this event. 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 2026-02-08 09:52:58.95 UTC. The measured peak count rate associated with the burst is 3595 (+111, -118) counts/s above the background in the combined data of all quadrants, with a total of 32443 (+740, -736) counts. The local mean background count rate was 1199 (+4, -5) counts/s. We measure a T90 of 22 (+1, -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/43677. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...