TITLE: GCN CIRCULAR NUMBER: 44725 SUBJECT: EP260527a/GRB 260527A: EP-FXT follow-up observation DATE: 26/05/28 15:02:24 GMT FROM: EP Team at NAOC/CAS <ep_ta@bao.ac.cn> J. Yang (ZZU), B. T. Wang (YNAO, CAS), D. F. Hu (PMO, CAS), J. P. Feng, B. Zhang (USTC), D. Zhu, K. J. Zhang (YNU) and W. D. Zhang (NAO,CAS) on behalf of the Einstein Probe (EP) team: The fast X-ray transient EP260527a triggered the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission (Yang et al., GCN 44718), was also detected by Konus-Wind and GECAM-B as GRB 260527A (Svinkin et al., GCN 44722, Yu et al., GCN 44724), and was followed by several optical telescopes (Aguilar-Ruiz et al., GCN 44719, Li et al., GCN 44720). EP-FXT performed a follow-up observation of EP260527a about 21 hours after the WXT detection, with an exposure time of 3.4 ks. The FXT telemetry data show that an uncatalogued source was detected within the WXT error circle at R.A. = 193.0548, DEC = 1.4806 (J2000) with an uncertainty of 10 arcsec (radius, 90% C.L. statistical and systematic). The FXT X-ray spectrum of this uncatalogued source can be fitted with an absorbed powerlaw with a hydrogen column density fixed at the Galactic value of 1.57 x 10^20 cm^-2 and a photon index of 2.6 (+1.2/-0.7). The derived unabsorbed 0.5-10 keV flux is approximately 7.7 (+3.7/-3.9) x 10^-14 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/44725. --- To unsubscribe, open this link in a web browser: https://gcn.nasa.gov/unsubscribe/eyJhbGciOiJIUzI1NiJ9.eyJlbWFpbCI6InZzbmV0LW...