TITLE: GCN CIRCULAR NUMBER: 39525 SUBJECT: EP250228a: Einstein Probe detection of an X-ray transient DATE: 25/02/28 07:09:00 GMT FROM: EP Team at NAOC/CAS <ep_ta@bao.ac.cn> H.Y. Liu (NAO, CAS), J.Q. Peng (IHEP, CAS), W. F. Wen(SZTU), J. H. Wu (GZHU), C.C. Jin (NAO, CAS) report on behalf of the Einstein Probe 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 EP250228a. The transient triggered EP-WXT (ID: 01709132122) at 2025-02-28T03:59:09 (UTC). The WXT position of the source is R.A. = 103.607 deg, DEC = -41.581 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 cirlce, an uncatalogued X-ray source was detected at R.A. = 103.6021 deg, DEC = -41.5715 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/39525. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...