Searches for class I methanol masers in the Galaxy

Recently a series of new surveys for class I methanol masers have been undertaken towards Galactic objects. These surveys have detected about 200 new class I methanol maser sources, equal to the total number of class I methanol masers detected in the past three decades. Analysis of the detection rates and emission properties of class I methanol masers in different targeted samples in these surveys reveals that the 1.1 mm Bolocam Galactic Plane Survey (BGPS) dust continuum sources are likely to provide more reliable targeting samples for further class I methanol maser searches. Such further searches will be an important supplement to the current Galactic molecular gas survey project (e.g., PMO-13.7 m CO Galactic survey) in accurately refining Galactic structures and investigating the formation of molecular clouds and stars in the Galaxy.