Determination of proper motions and membership of the open star cluster NGC2548

Abstract

Absolute proper motions, their corresponding errors and membership probabilities of 501 stars in the intermediate-age open cluster NGC2548 region are determined from MAMA measurements of 10 photographic plates. The plates have the maximum epoch difference of 82 years and they were taken with the double astrograph at Zo-Se station of Shanghai Observatory, which has an aperture of 40 cm and a plate scale of 30"/mm. The average proper motion precision is 1.18 mas/yr. These proper motions are used to determine the membership probabilities of stars in the region. The number of stars with membership probabilities higher than 0.7 is 165.