The absolute rotation of the milky way

The authors have analyzed the proper motions of 122 FK4 and FK4 Sup stars in the distance interval 300 pc to about 1 kpc and with spectral types earlier than B3. The analysis was made in the FK5 system and individual corrections were applied to the FK4 stars. After eliminating the systematic motions arising from the motion of the Sun and from differential galactic rotation (generally adopted values for the solar motion and for Oort's constants A, B were used) the authors found a significant dependence of the residuals μ_l cos b on the galactic latitude. From this finding it is argued that there may exist local effects in the galactic velocity field such that the customary interpretation of the average Oort constant B (averaged over galactic latitude) for the absolute rotation of the Milky Way may not be justified.