PROPER MOTIONS OF STARS IN THE REGION OF THE OPEN CLUSTER NGC-2286 AND ITS MEMBERSHIP STUDY

Relative proper motions, their corresponding observed errors and membe rship probabilities of 2400 stars in the open cluster NGC 2286 region are determined from ASTROSCAN measurements of 8 plates made at Leiden Observatory. The plates have the maximum epoch difference of some 70 y ears and were taken with the double astrograph at Zo-Se station of Sha nghai Observatory, which has an aperture of 40 cm, a focal length of 6 .9 m and a scale of 30 arcsec/mm. The number of stars with membership probabilities higher than 0.7 and radial distances from the cluster ce ntre less than 12' is 90. The average standard errors of proper motion s vary from +/-0.0007''/yr for bright stars in the inner part of the f ield to some +/-0.0016/yr for faint stars in the outer part of the fie ld, and are statistically dependent on the number of measured plates p er star. It is found from an analysis of the surface number density di stribution of cluster members that the angular radius of NGC 2286 is s ome 12' and the corresponding linear radius 4.5 pc.