Average proper motion of the sample in the sky. Only the stars selected according to the criteria set in Sect. 2 are used. Top: proper motion in right ascension. Bottom: proper motion in declination. Only a few globular clusters, the Large Magellanic cloud, and the most inner parts of the Sgr core are noticeable as the rest of the field is dominated by the solar reflex (peculiar motion of the Sun and rotation of the local standard of rest).