EP240626a: EP-FXT detection of the X-ray emission

Following the detection of the fast X-ray transient EP240626a (Wu et al., GCN 36766), we performed an observation of EP240626a with the Follow-up X-ray Telescope (FXT) on board the Einstein Probe mission. The observation began at 2024-06-26T08:58:37 (UTC), about 2.5 hours after the EP-WXT trigger. The exposure time is 6266 seconds. A faint source was detected at R.A. = 263.0171 deg, DEC = -13.0490 deg, with an uncertainty of 30 arcsec (radius, 90% C.L. statistical and systematic). The spectrum can be fitted with an absorbed power-law model with a photon index of 1.2(+0.7/-0.6) and the column density fixed at the Galactic value of 1.8 x 10^21 cm^-2. The derived unabsorbed flux in 0.5-10 keV is 1.5(+1.2/-0.7) x 10^-13 erg/s/cm^2 (90% C.L.). There is no cataloged X-ray source within the error circle, suggesting this source being associated with EP240626a. Please note that EP-FXT is currently undergoing in-flight calibration. The derived source parameters may be subject to larger uncertainties, so please use them with caution. 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).