  We demonstrate a one-dimensional optical lattice clock with ultracold 171Yb
atoms, which is free from the linear Zeeman effect. The absolute frequency of
the 1S0(F = 1/2) - 3P0(F = 1/2) clock transition in 171Yb is determined to be
518 295 836 590 864(28) Hz with respect to the SI second.
