  A spectrometer for ultra high-resolution spectroscopy of molecular iodine at
wave length 501.7 nm, near the dissociation limit is described. Line shapes
about 30 kHz wide (HWHM) were obtained using saturation spectroscopy in a
pumped cell. The frequency of an Ar+ laser was locked to a hyperfine component
of the R(26)62-0 transition and the first absolute frequency measurement of
this line is reported.
