Astrometry of globular clusters (47 Tuc)

Proper motion and membership probabilities are tabulated for 3076 stars within 32 arcmin of the cluster center. A proper motion of 47 Tuc relative to the SMC is derived, which relies on the assumption that the mean proper motion of field stars is the same as that in the nearby field of NGC 362, and on the detection of SMC stars in that field.

The resulting space motion confirms the membership of 47 Tuc in the rapidly rotating, flattened, metal-rich disk subgroup of the galactic cluster system. Relative proper motions for stars centered on the globular cluster NGC 362 are determined. NGC 362 is found to exhibit a highly eccentric orbit, typical for a member of the halo subgroup of the galactic globular cluster system.