Milli-Arcsecond Proper Motions in the Pleiades

As a first step in our open cluster programme, a preliminary catalogue of proper motions and photographic B, V magnitudes for stars up to 18 mag within a region centred near Alcyone is presented. The catalogue is based on MAMA measurements of plates taken with the Tautenburg Schmidt telescope. A preliminary survey includes approx. 20,000 stars and covers a total field of about 9 square degrees. For stars brighter than B = 18 mag an accuracy of 0.0S mag and 2.5 mas/year has been estimated for photometric data and proper motions, respectively. The results of the determination of the Pleiades membership up to magnitude 18 are presented.