LAUSR

We report the absolute frequency measurement of the unperturbed optical clock transition 1S0 – 3P0 in 171Yb performed with an optical lattice frequency standard. Traceability to the International System of Units is provided by a link to International Atomic Time. The measurement result is 518 295 836 590 863.61(13) Hz with a relative standard uncertainty of 2.6×10−16, obtained operating our Yb optical frequency standard intermittently for 5 months. The optical frequency standard contributes with a systematic uncertainty of 2.8×10−17.