TITLE: GCN CIRCULAR NUMBER: 38457 SUBJECT: EP241206a: EP detection of a fast X-ray transient DATE: 24/12/07 14:42:53 GMT FROM: EP Team at NAOC/CAS <ep_ta@bao.ac.cn> Y.-H. I. Yin (NJU), C. Y. Wang (THU), D. H. Zhao (NAO,CAS), H. W. Pan (NAO,CAS) report on behalf of the Einstein Probe team: We report on the detection of a fast X-ray transient detected by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, EP241206a (Obs. ID: 11900018538 and 11908897056). The transient was first detected with WXT at around 2024-12-06T16:34:47 (UTC) and lasted for about 400 seconds. The WXT position of EP241206a is R.A.= 34.702 deg, DEC = 38.914 deg (J2000) with an uncertainty of 3.78 arcmin (radius, 90% C.L. statistical and systematic). The average 0.5-4 keV spectrum can be fitted with an absorbed power law with a photon index of 1.96 (+0.52/-0.40) (with a column density fixed at the Galactic value of 5.47 x 10^20 cm^-2). The derived average unabsorbed 0.5-4 keV flux is 4.92 (+1.19/-1.24) x 10^(-10) erg/s/cm^2. We plan to perform a target of opportunity observation with the Follow-up X-ray Telescope (FXT) on board EP. Further follow-up observations are encouraged to explore the origin of EP241206a. 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/38457. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...