TITLE: GCN CIRCULAR NUMBER: 41978 SUBJECT: GRB 250914A: AstroSat CZTI detection DATE: 25/09/25 05:57:47 GMT FROM: Gaurav Waratkar at Caltech <gauravwaratkar@iitb.ac.in> A. Arya (IITB), A. Goyal (IITB), S. Salunke (IUCAA), M. Tembhurnikar (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 a long-duration GRB 250914A which was also detected by Konus-Wind (GCN Notices). 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 2025-09-14 20:52:17.50 UTC. The measured peak count rate associated with the burst is 234 (+35, -27) counts/s above the background in the combined data of all quadrants, with a total of 2354 (+246, -269) counts. The local mean background count rate was 221 (+3, -4) counts/s. Using cumulative rates, we measure a T90 of 18 (+2, -3) s. The source was also clearly detected in the CsI anticoincidence (Veto) detector in the 100-500 keV energy range. The light curve showed single peak of emission with the strongest peak at 2025-09-14 20:52:17.33 UTC. The measured peak count rate associated with the burst is 457 (+75, -67) counts/s above the background in the combined data of all quadrants, with a total of 2976 (+437, -444) counts. The local mean background count rate was 1776 (+8, -7) counts/s. We measure a T90 of 13 (+3, -3) 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/41978. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...