TITLE: GCN CIRCULAR NUMBER: 41459 SUBJECT: EP250821a: Einstein Probe detection of an X-ray transient DATE: 25/08/21 08:25:08 GMT FROM: EP Team at NAOC/CAS <ep_ta@bao.ac.cn> D. F. Hu, Y. F. Liang (PMO, CAS), C. C. Jin (NAO, CAS) on behalf of the Einstein Probe (EP) team: We report on the detection of an X-ray transient by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated EP250821a. The transient triggered EP-WXT (ID: 01709200464) at 2025-08-21T07:18:29 (UTC). The WXT position of the source is R.A. = 289.856 deg, DEC = -43.410 deg (J2000) with an uncertainty of 3 arcmin in radius (90% C.L. statistical and systematic). A follow-up observation with the Follow-up X-ray Telescope (FXT) was performed automatically. Within the WXT error circle, an uncatalogued X-ray source was detected at R.A. = 289.8828 deg, DEC = -43.3816 deg (J2000) with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic). 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/41459. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...