Rest frequencies of methanol maser lines

New data have been obtained between 10 and 27GHz and between 60 and 119GHz. 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 (<0.5km/s) 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 energy levels (<20cm^-1^ or 30K), are potentially detectable in cold clouds.