TITLE: GCN CIRCULAR NUMBER: 44796 SUBJECT: EP260602d: Einstein Probe detection of a fast X-ray transient DATE: 26/06/03 09:46:29 GMT FROM: EP Team at NAOC/CAS <ep_ta@bao.ac.cn> J.Y. Cao, Z. X. Li, G. L. Huang, (IHEP, CAS), J. W. Hu, Y. Liu (NAO, CAS) on behalf of the Einstein Probe (EP) team: We report on the detection of a fast X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP260602d. The source did not trigger the WXT on-board trigger unit. A GCN Notice was sent manually (trigger ID: 13616654987). The ground analysis of the WXT data shows that the event started at T0=2026-06-02T21:13:25 (UTC) and lasted for about 200 s. The WXT position of the source is R.A. = 267.958 deg, DEC = 18.173 deg (J2000) with an uncertainty of 2.3 arcmin in radius (90% C.L. statistical and systematic). The average WXT 0.5-4 keV spectrum can be fitted with an absorbed power law with a fixed Galactic hydrogen column density of 6.7 × 10^20 cm^-2, and a photon index of 0.8 (-0.5, +0.6). The derived average unabsorbed 0.5-4 keV flux is 1.4 (-0.9, +0.7)×10^(-10) erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters. A Target-of-Opportunity observation with the Follow-up X-ray Telescope (FXT) has been scheduled. Further information will be updated when the telemetry data is received. Launched on January 9, 2024, EP is a space X-ray observatory to monitor the soft X-ray sky with X-ray follow-up capability (Yuan et al. 2022, Handbook of X-ray and Gamma-ray Astrophysics). View this GCN Circular online at https://gcn.nasa.gov/circulars/44796. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...