Local kinematics of classical cepheids

Combining Hipparcos proper motions and the radial velocity data, we have studied the Cepheid kinematics on the basis of the three-dimensional Ogorodnikov-Milne model. The results seem to show a slight contracting motion of the Galaxy in the solar neighbourhood, partial derivative V-theta/partial derivative theta/R = -2.60 +/- 1.07 km s(-1) kpc(-1), which is along the solar circle. Under the hypothesis of a circular stream model, we have determined the galactic rotation V-theta = -240.5 +/- 10.2 km s(-1) for the classical Cepheids.