TITLE: GCN CIRCULAR NUMBER: 38490 SUBJECT: GRB 241209C: AstroSat CZTI detection DATE: 24/12/09 12:29:50 GMT FROM: Gaurav Waratkar at IIT Bombay <gauravwaratkar@iitb.ac.in> J. Joshi (IUCAA), G. Waratkar (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 241209C which was also detected by Fermi/GBM (Fermi-GBM Team, GCN Circ. 38482). The source was clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve peaks at 2024-12-09 07:22:58.21 UTC. The measured peak count rate associated with the burst is 255 (+79, -35) counts/s above the background in the combined data of all quadrants, with a total of 1341 (+212, -365) counts. The local mean background count rate was 1635 (+16, -10) counts/s. We measure a T90 of 6.6 (+0.5, -0.9) 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/38490. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...