  We report accurate laboratory measurements of selected methanol transition
frequencies between 0.834 and 230 GHz in order to facilitate astronomical
velocity analyses. New data have been obtained between 10 and 27 GHz and
between 60 and 119 GHz. Emphasis has been put on known or potential
interstellar maser lines as well as on transitions suitable for the
investigation of cold dark clouds. Because of the narrow line widths (<0.5
kms-1) of maser lines and lines detected in dark molecular clouds, accurate
frequencies are needed for comparison of the velocities of different methanol
lines with each other as well as with lines from other species. In particular,
frequencies for a comprehensive set of transitions are given which, because of
their low level energies (< 20 cm-1 or 30 K) are potentially detectable in cold
clouds. Global Hamiltonian fits generally do not yet yield the required
accuracy. Additionally, we report transition frequencies for other lines that
may be used to test and to improve existing Hamiltonian models.
