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一般所认为的要少。大多数视差测定都是20多年前的事了，因此即使使用传统设备，误差也比近年来可能出现的误差要大得多。自1967年以来，这个程序一直利用这种精度的提高来获得视差和固有运动。这是目前活跃的两个最广泛的此类项目之一。它将继续丰富低主序星以及亚矮星型恒星的高精度视差和光度测量的数量。这些恒星是银河系中最古老的恒星之一，它们的视差和距离现在还不为人所知。预计该计划将以比现在更高的精度校准这些老恒星的距离尺度。光度测定和可能的径向速度是必要的。学生们也将在项目的各个方面接受培训。

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.