Photoelectric radial velocities - I. Technique.

A NOVA computer controlled, rapid scanning radial velocity spectrometer has been constructed for use at the Coude' focus of the Radcliffe I 88-cm reflector. Designed specifically for use in a study of Al Velorum stars, it has measured radial velocities at rnv = in 3 min for the Fo stars V7o3 Sco and Al Velorum. The accuracy is currently 13 km -I Improvements are described to obtain an expected time resolution of 5 min at mv = 10.