TITLE: GCN CIRCULAR NUMBER: 43447 SUBJECT: EP260119a: EP-WXT detection of a fast X-ray transient DATE: 26/01/19 08:03:26 GMT FROM: EP Team at NAOC/CAS <ep_ta@bao.ac.cn> Y. H. Jiang (NJU), D. Zhu, K.J. Zhang ,Y.H. Cheng (SWIFAR,YNU), R. X. Hu (WHU)，H. Sun (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 EP260119a. The source has a signal-to-noise ratio of 7.5. But the total number of counts is insufficient to trigger the WXT on-board trigger unit. The event started at 2026-01-19T00:13:48 (UTC) and lasted for almost 300 seconds. The WXT position of the source is R.A. = 158.082 deg, DEC = 65.505 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 photon index of 1.8(-/+0.6) and with a fixed galactic hydrogen column density of 1.2 x 10^20 cm^-2. The derived average unabsorbed 0.5-4 keV flux is 4.4 (-1.3/+1.8) x 10^-11 erg/s/cm^2. The peak flux in the 0.5-4 keV band reaches 4.8 x 10^-10 erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters. The stellar flare origin can not be fully ruled out. A follow-up observation with EP-FXT has been scheduled. 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/43447. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...