TITLE: GCN CIRCULAR NUMBER: 44702 SUBJECT: GRB 260523B: AstroSat CZTI detection DATE: 26/05/25 11:38:44 GMT FROM: Anuraag Arya at IIT Bombay <aryaanuraag910@gmail.com> A. Arya (IITB), A. Goyal (IITB), Harsha K. H. (IUCAA), S. Salunke (IUCAA), M. Tembhurnikar (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 short GRB 260523B which was also detected by Fermi/GBM (Fermi GBM team, GCN Circ. 44699). The source was clearly detected in the CZT detectors in the 20-200 keV energy range. The light curve peaks at 2026-05-23 19:26:02.85 UTC. The measured peak count rate associated with the burst is 259 (+123, -28) counts/s above the background in the combined data of three quadrants (out of four), with a total of 259 (+56, -54) counts. The local mean background count rate was 184 (+4, -7) counts/s. Using cumulative rates, we measure a T90 of 1.74 (+0.57, -0.46) 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 2026-05-23 19:26:02.79 UTC. The measured peak count rate associated with the burst is 318 (+68, -53) counts/s above the background in the combined data of all quadrants, with a total of 408 (+166, -174) counts. The local mean background count rate was 1282 (+11, -12) counts/s. Due to the intrinsic 1 s binning of veto data, we cannot reliably estimate a T90 for our detection. 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/517260365.54/ET20260523T192602_... 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/44702. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...