TITLE: GCN CIRCULAR NUMBER: 43080 SUBJECT: GRB 251211B: AstroSat CZTI detection DATE: 25/12/13 04:13:33 GMT FROM: Utkarsh Pathak at IIT Bombay <utkarshpathak.07@gmail.com> A. Arya (IITB), A. Goyal (IITB), U. Pathak (IITB), M. Tembhurnikar (IUCAA), S. Salunke (IUCAA), Harsha K. H. (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 GRB 251211B, which was also detected by Fermi/GBM (Fermi GBM Team, GCN Circ. 43072). The source was faintly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2025-12-11 20:32:04.31 UTC. The measured peak count rate associated with the burst is 176 (+60, -53) counts/s above the background in the combined data of all quadrants, with a total of 367 (+222, -238) counts. The local mean background count rate was 1180 (+8, -8) counts/s. Due to the intrinsic 1 s binning of veto data and the relatively faint detection, we cannot reliably estimate a T90 for this burst. 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/43080. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...