TITLE: GCN CIRCULAR NUMBER: 41260 SUBJECT: GRB 250806A: EP-FXT observation DATE: 25/08/07 09:46:25 GMT FROM: EP Team at NAOC/CAS <ep_ta@bao.ac.cn> R. D. Liang, H. N. Yang (NAO, CAS), Y. J. Zhang (THU), W. D. Zhang (NAO, CAS) report on behalf of the Einstein Probe team: GCN #41243 reported the detection of GRB 250806A with SVOM on 2025-08-06T08:00:11 UTC (T0) and the X-ray conterpart was detected with swift-XRT (GCN #41249). The Follow-up X-ray Telescope (FXT) on board Einstein Probe observed GRB 250806A about 4 ks (2025-08-06T09:04:02, UTC) after T0, with an exposure time of 790 seconds. On-ground analysis of the FXT data found an uncatalogued source at R.A. = 348.4308, DEC =1.3556 (J2000) with an uncertainty of about 10 arcsec (radius, 90% C.L. statistical and systematic), which is consistent positionally with the swift-XRT transient (GCN #41249). The angular distance between the FXT position and SVOM-MXT detection (GCN #41243) is 106 arcseconds. The average 0.5-10 keV spectrum can be fitted with an absorbed power law with a Galactic hydrogen column density of 4.5 x 10^20 cm^-2 and a photon index of 1.25 (-1.14/+1.11). The derived average unabsorbed 0.5-10 keV flux is 1.49 (-0.98/+6.08) x 10^(-12) erg/s/cm^2. The uncertainties are at the 90% confidence level for the above parameters. 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/41260. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...