We have analyzed VLBA observations towards W49N using the OH maser

frequencies, 1612 MHz, 1665 MHz and 1667 MHz. The resolution is about
20 by 15 mas at a position angle of 84 degrees.



More than one hundred masers spots were detected, most of them at 1665
and 1667 MHz and eleven at 1612 MHz. A dozen of Zeeman pairs have been
identified with longitudinal local magnetic fields, at the maser emitting
regions, ranging from -10 mili Gauss to about 6 mili Gauss.


The deconvolved angular sizes (major axis)
range from 70 to 30 mas,
which for a distance of 14 kpc are about 1000 and 400 AU. The axial
ratios range from about 1.5:1 to 3:1. These apparent angular sizes,
clearly larger than the beam, are due to interstellar scattering
arising from electron density inhomogeneities of the interstellar medium.
For W49N, which is at 14 Kpc, the line of sight intersects many scattering
clumps. Therefore, based on the apparent angular sizes, the average
properties of these homogeneities may be estimated.



The principal axis (PA) of the spots is typically about 110 degrees and
the galactic plane is at a position angle of 30 degrees. This implies that
the PA of the spots is nearly perpendicular to the galactic plane.
This is interpreted as the result of density fluctuations elongated along
an ordered component of the galactic magnetic field parallel to the
galactic plane.



Details of the Zeemans pairs and the estimated magnetic fields have been

determined along
with the spatial distributions of the spots. Also, an
analysis of the distributions of the axes and PA's of the spots has been
carried out.