  The first images of 6.7-GHz methanol masers in the massive star-forming
regions DR21(OH) and DR21(OH)N are presented. By measuring the shapes, radial
velocities and polarization properties of these masers it is possible to map
out the structure, kinematics and magnetic fields in the molecular gas that
surrounds newly-formed massive stars. The intrinsic angular resolution of the
observations was 43 mas (~100 AU at the distance of DR21), but structures far
smaller than this were revealed by employing a non-standard mapping technique.
This technique was used in an attempt to identify the physical structure (e.g.
disc, outflow, shock) associated with the methanol masers. Two distinct
star-forming centres were identified. In DR21(OH) the masers had a linear
morphology, and the individual maser spots each displayed an internal velocity
gradient in the same direction as the large-scale structure. They were detected
at the same position as the OH 1.7-GHz ground-state masers, close to the centre
of an outflow traced by CO and class I methanol masers. The shape and velocity
gradients of the masers suggests that they probably delineate a shock. In
DR21(OH)N the methanol masers trace an arc with a double-peaked profile and a
complex velocity gradient. This velocity gradient closely resembles that of a
Keplerian disc. The masers in the arc are 4.5% linearly polarized, with a
polarization angle that indicates that the magnetic field direction is roughly
perpendicular to the large-scale magnetic field in the region (indicated by
lower angular resolution measurements of the CO and dust polarization). The
suitability of channel-by-channel centroid mapping is discussed as an improved
and viable means to maximise the information gained from the data.
