Fast X-ray transient EP260214b detected by Einstein Probe at z=1.208

AI Summary

Einstein Probe's Wide-field X-ray Telescope detected a fast X-ray transient (EP260214b) on 2026-02-14 lasting ~50 seconds with an average flux of 2.1×10⁻⁹ erg/s/cm² (0.5-4 keV). The transient was rapidly localized to RA=191.26°, Dec=23.857° with a 3 arcmin error radius, and an optical counterpart was identified at redshift z=1.208. Multi-wavelength follow-up observations detected optical emission (r~21-22 mag) that faded over days, and radio observations revealed a 0.04 mJy detection at 6 GHz ~34 days post-trigger, indicating ongoing emission from this extragalactic transient.