TITLE: GCN CIRCULAR NUMBER: 43791 SUBJECT: EP260221a: Einstein Probe detection of an X-ray transient DATE: 26/02/21 13:34:01 GMT FROM: EP Team at NAOC/CAS <ep_ta@bao.ac.cn> M.-H. Zhang, X. X. Sun, Tian-Yu Liu, Y. Liu (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 EP260221a. The transient triggered EP-WXT (ID: 01709258521) at 2026-02-21T11:43:14 (UTC). The WXT position of the source is R.A. = 178.749 deg, DEC = -20.978 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 at 2026-02-21T12:44:34 (UTC). Within the WXT error circle, an uncatalogued X-ray source was detected at R.A. = 178.7568 deg, DEC = -20.9847 deg (J2000) with an uncertainty of 20 arcsec in radius (90% C.L. statistical and systematic). 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/43791. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...