TITLE: GCN CIRCULAR NUMBER: 41221 SUBJECT: EP250802a: Einstein Probe detection of an X-ray transient DATE: 25/08/03 12:45:12 GMT FROM: EP Team at NAOC/CAS <ep_ta@bao.ac.cn> Y.-H. I. Yin (NJU), X. Mao, T. Zhao, C. C. Jin (NAO, CAS) on behalf of the Einstein Probe (EP) team: We report on the detection of an X-ray transient by EP-WXT through ground data analysis, designated EP250802a (ObsID:06800000790). The transient was detected at 2025-08-02 10:37:08 (UTC). The WXT position of the source is R.A. = 303.321 deg, DEC = 24.814 deg (J2000) with an uncertainty of 3.1 arcmin (radius, 90% C.L. statistical and systematic). The transient event lasted for about 650 seconds.  The average 0.5-4 keV spectrum can be fitted with an absorbed powerlaw model, with absorption fixed at the Galactic value of 3.5 x 10^21 cm^-2 and a photon index of 2.81 (+/-0.47). The unabsorbed average 0.5-4 keV flux is estimated to be 3.81 (-0.57, +0.67) x 10^-11 erg/s/cm2. The peak flux is about 1.16 (-0.20, +0.25) x 10^-10 erg/s/cm2. The uncertainties are at the 90% confidence level for the above parameters.  Further FXT observations are 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/41221. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...