球状星团NGC4147的绝对自行和颜色星等图

ABSOLUTE PROPER MOTIONS AND COLOUR-MAGNITUDE DIAGRAMS OF THE GLOBULAR CLUSTER NGC 4147

本文以上海天文台佘山40厘米折射望远镜于1958年拍摄的3张照相底片为第一期，印度Kavalur的234米VainuBappu望远镜于1996年用CCD拍摄的4幅图像为第二期，使用Brosche等1985年发表的球状星团NGC4147天区42颗恒星的位置和绝对自行作为参考架，用中心重叠法进行天体测量归算，得到了这个星团中心附近11'×11'天区内到B＝17.6为止115颗恒星的位置和绝对自行，利用这些自行对成员概率作了估计.本文还给出了用VainuBappu望远镜CCD测光结果得到的这个星因水平文和巨星支恒星V与B-V．V－R和V－I颜色星等图，并对这些颜色星等图和团自行作了讨论，得到这个星团的赤经方向绝对自行为-2.82±0.49mas／yr，赤纬方向绝对自行为2.37±0.43mas／yr.

The astrometry and photometry of 115 stars down to B = 17.6 in the region ofabout 11×11' around the cluster NGC 4147 were made. In the astrometric reduction,three earlier epoch plates taken with the 40cm refractor (f= 6895mm) at SheshanStation of Shanghai Observatory in 1958 and four recent B-passband CCD framestaken with the 2.34m Vainu Bappu Telescope(f= 7558mm) at Kavalur, India wereused. In addition, the data in Table ill of the paper [6] were used as a referenceframe and a set of earlier epoch positions. The reduction was done by the centraloverlapping principle. With the new data of proper inctions, the membershipprobabilities of stars were determined. Furthermore, three colour-magnitude diagrams(CMDs) of V versus B-U V-R and V-I, respectively, for stars of HB and GBs wereconstructed with the CCD photometry of the Vainu Bappu Telescope. Somediscussions about these CMDs and the cluster proper motion are made and an absoluteproper inchon of - 2.82±0.49mas / yr in R A. and 2.37 ± 0.43mas / yr in Decl. forthe cluster has been obtained.