  Full-polarization MERLIN and VLBA observations of the 1720-MHz maser emission
from the OH molecule in the supernova remnant W44 are presented. Zeeman
splitting has been directly resolved between right- and left-circularly
polarized spectra indicating magnetic field strengths of B~0.50 mG. The
position angle of the linear polarization is in good agreement with the
orientation of the shocked gas at the supernova remnant/molecular cloud
interface. Based on MERLIN data having a resolution of 200 milliarcseconds
(mas) and VLBA data with a resolution of 15 mas, the masers are measured to
have deconvolved angular sizes of 50 to 350 mas (150 to 1000 AU) with compact
cores 20 mas (60 AU) in size, consistent with theoretical expectation and
previous observations.
