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Astron. Astrophys. Suppl. Ser. 131, 89-98

Determination of proper motions and membership of the open clusters NGC 1750 and NGC 1758

K.-P. Tian1,2 - J.-L. Zhao2,1 - Zh.-Y. Shao1 - P.B. Stetson3

Send offprint request: K.-P. Tian,

1 - Shanghai Astronomical Observatory, CAS, Shanghai 200030, P.R. China
2 - CCAST(WORLD LABORATORY) P.O. Box 8730, Beijing, 100080, P.R. China
3 - Dominion Astrophysical Observatory, Herzberg Institute of Astrophsics, National Research Council of Canada, 5071 West Saanich Road, Victoria, British Columbia V8X 4M6, Canada

Received November 12, 1997; accepted February 18, 1998


The kinematic state of the open clusters NGC 1750 and NGC 1758 has been studied using newly determined proper motions for 540 stars in a field of 1$.\!\!^\circ$5$\times$1$.\!\!^\circ$5 in the Taurus dark cloud region. The proper motions are obtained from the reduction of PDS measurements of 20 plates that span a total time interval of 68 years, resulting in an average proper motion accuracy of 0.67 mas/yr. These proper motions are used to determine the membership probabilities of stars in the region by means of a new, improved method described in this paper. Of the 540 stars analyzed here, 332 are found to be probable members of NGC 1750, and 23 are probable members of NGC 1758. The core radii of NGC 1750 and NGC 1758 are determined to be 17${}^{\prime}$.2 and 2${}^{\prime}$.25 respectively.

Key words: open cluster: NGC 1750; NGC 1758 -- astrometry

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