Measurement of Stellar Parallaxes and Proper Motions

附近恒星的三角视差在数量上和精度上都比人们通常认为的要少。大多数视差测定已有二十多年的历史，因此其误差比近年来可能出现的误差要大得多，即使使用传统设备也是如此。自1967年以来，该程序在获得视差和自然运动方面利用了这一精度的提高。它是目前活跃的两个最广泛的此类项目之一。它将继续丰富较低主序恒星以及亚矮型恒星的高精度视差和光度测量的数量。这些恒星是我们银河系中最古老的恒星之一，它们的视差和距离现在还不是很清楚。预计该计划将以比目前可用的更高的精度来校准这些老恒星的距离标度。必要时可获得光度测量和可能的径向速度。它还打算让学生接受该计划各个方面的培训。

Trigonometric parallaxes of nearby stars are fewer in number and lower in precision than is generally perceived. Most parallax determinations are more than twenty years old and thus have errors much larger than those possible in recent years, even with conventional equipment. This program has made use of this increase in precision in obtaining parallaxes and proper motions since 1967. It is one of the two most extensive such programs now active. It would continue to enrich the number of high-precision parallaxes and photometry of stars of the lower main sequence, as well as subdwarf type stars. These stars are among the oldest in our Galaxy, and their parallaxes and distances are not now well known. It is expected that the program will calibrate the distance scale of these old stars with much greater precision than is now available. Photometry and possibly radial velocities are acquired as necessary. It is also intended that students will be trained in all aspects of the program.