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Class I methanol masers are believed to be produced in the shock-excitedenvironment around star-forming regions. Many authors have argued that theappearance of various subsets of class I masers may be indicative of specificevolutionary stages of star formation or excitation conditions. Until recently,however, no major interferometer was capable of imaging the important 36 GHztransition. We report on Expanded Very Large Array observations of the 36 GHzmethanol masers and Submillimeter Array observations of the 229 GHz methanolmasers in DR21(OH), DR21N, and DR21W. The distribution of 36 GHz masers in theoutflow of DR21(OH) is similar to that of the other class I methanoltransitions, with numerous multitransition spatial overlaps. At the site of themain continuum source in DR21(OH), class I masers at 36 and 229 GHz are foundin virtual overlap with class II 6.7 GHz masers. To the south of the outflow,the 36 GHz masers are scattered over a large region but usually do not appearcoincident with 44 GHz masers. In DR21W we detect an "S-curve" signature inStokes V that implies a large value of the magnetic field strength ifinterpreted as due to Zeeman splitting, suggesting either that class I masersmay exist at higher densities than previously believed or that the directZeeman interpretation of S-curve Stokes V profiles in class I masers may beincorrect. We find a diverse variety of different maser phenomena in thesesources, suggestive of differing physical conditions among them.

First Interferometric Images of the 36 GHz Methanol Masers in the DR21 Complex