Determination of proper motions and membership of the open star cluster NGC 2548

Abstract

Absolute proper motions, their corresponding errors and membership probabilities of 501 stars in the intermediate-age open cluster NGC 2548 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 Zô-Sè station of Shanghai Observatory, which has an aperture of 40 cm and a plate scale of 30 ″ mm-1. The average proper motion precision is 1.18 mas yr-1. 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.