Kinematics of the Galactic Globular Cluster System

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Abstract
Constraints on cluster kinematics proper motions, radial velocities and tidal radii are reviewed. Analysis of the cluster radial velocity distribution suggests a rotation law for the system in which the specific angular momentum is nearby independent of galactocentric distance, and the residual velocity dispersion is isotropic. However, the absence of severely tidally truncated clusters indicates that nearly radial orbits are absent from this distribution. The kinematic properties of the remote halo clusters remain largely indeterminate. Absolute proper motions measured directly with respect to background galaxies and quasars are needed to determine the kinematics of these objects, and also to elucidate the process of tidal stripping.