Structure of the object W3 OH in hydroxyl maser lines

The structure of the gas-dust complex W3 OH has been investigated in the main hydroxyl radio line at 1665 MHz with the QUASAR system in left- and right-hand circular polarizations. The emission dominates in right-hand circular polarization. Spectra have been taken on single dishes and interferometers. The spectral features become narrower with increasing baseline length, which is determined by compact knots in sources. The correlated flux densities on maximum-length baselines do not exceed 20 and 10 Jy in right- and left-hand circular polarizations, respectively. Radio maps have been obtained in both polarizations with various angular resolutions from 5 to 200 mas. The object W3 OH located in a Galactic arm is observed in the transverse direction, which reduces considerably the scattering φsc ⩽ 2 mas. A number of fragments are observed only in one of the polarizations; the emission from three sources is observed in both polarizations with a frequency separation reaching Δf = ±10.6 kHz, corresponding to the Zeeman splitting in a magnetic field H = 7.6 mG.