The comparison of the spectra, obtained at Medicina with the spectra, obtained in previous searches confirmed that variability of methanol masers is a more common phenomenon than expected and deserves more monitoring observations.
Our results confirm that 6.7 GHz masers are mostly concentrated in the inner Galaxy. We find that the detection rate of 6.7 GHz masers toward the center of the Galaxy is higher than in the other directions. Association of the 6.7 GHz masers with faint ultracompact HII regions is demonstrated. The 6.7 GHz methanol masers have large velocity dispersion and large offset from the velocity of parent molecular clouds.
We are grateful to the staff of the Medicina Observatory for providing help during the observations. V.I.S., S.V.K., I.E.V. were partly supported by the ISF grant MND000. We are grateful to David A. Lyder for sending his article prior to publication.
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