Refined proper motions of some high-velocity stars

We improve the Gaia DR2 proper motions of nine high-velocity stars with the highest proper-motion errors. We reduce the transversal-velocity errors for our stars from to 1.5-746 km/s. We combine our refined proper motions with published radial-velocity and distance data to compute the orbits of these stars in terms of the axisymmetric potential model. Most of the stars considered move in rosette-shaped orbits. J154556.10+243708.9 to move in a highly-elongated loop-shaped orbit, and HVS22 star escapes from the Galaxy.