The detection of a strong new maser emission line from the 5(-1)-4(0)E transition of methanol toward DR 21(OH) is reported. Interferometric observations with a resolution of 8.3 arcsec x 6.2 arcsec show that the line does not coincide in position with any of the known maser or infrared emission features toward this source. This strongly indicates an excitation mechanism for this methanol maser which is different from the physical conditions leading to the excitation of the water and OH masers. In addition, maser emission is found toward a condensation which has been detected in emission in the 2(11)-2(12) transition of formaldehyde. Besides maser emission, thermal emission lines from several compact sources are detected. Two of these sources are found very close to the OH maser position.
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Batrla et al. (1988) studied this question.