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

¹ Shanghai Astronomical Observatory, CAS Shanghai 200030, PR China
² Chinese National Observatories, CAS, PR China
³ Joint Lab of Optical Astronomy, CAS, PR China
⁴ Departament d'Astronomia i Mateorologia, Universitat de Barcelona, Avda. Diagonal 647, 08028 Barcelona, Spain
⁵ Institut d'Estudis Espacials de Catalunya IEEC, Edif. Nexus Gran Capità 24, 08034 Barcelona, Spain
⁶ CCAST (WORLD LABORATORY) PO Box 8730, Beijing 100080, PR China
⁷ Centre d'Analyse des Images, Observatoire de Paris, Bâtiment Perrault, 77 Av. Denfert-Rochereau, 75014 Paris, France

Corresponding author: L. Balaguer-Núñez, Lola.Balaguer@am.ub.es

Received: 7 May 2001
Accepted: 18 October 2001

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.