Measurement of Parallaxes and Proper Motions

亚瑟·厄普格伦博士将继续执行一项计划，用货车弗莱克天文台的61厘米望远镜测量恒星的弛豫和自行。他将获得低主序星和次矮星的高精度星表和测光。这些恒星是我们银河系中最古老的恒星之一，但它们的半径和距离并不为人所知。预计厄普格伦博士的观测将允许校准这些古老恒星的距离尺度，其精度比现在高得多。研究生和本科生将参与该计划的各个方面。附近恒星的三角测量在数量上和精度上都比通常认为的要少。在太阳系之外，即使是最近的恒星的距离也令人惊讶地鲜为人知。除了百分之几以外，所有已发表的视差图都是关于距离如此遥远的恒星，以至于视差法不适用。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大得多。自1967年以来，Upgren博士的计划已经利用了在获得松弛和自行方面的精确度的增加。他的项目是目前最广泛的两个此类项目之一。

Dr. Arthur Upgren will continue a program of measuring parallaxes and proper motions of stars with the 61-cm telescope of the Van Vleck Observatory. He will obtain high precision parallaxes and photometry of stars of the lower main sequence as well as of subdwarf stars. These stars are among the oldest in our Galaxy, but their parallaxes and distances are not well known. It is expected that Dr. Upgren's observations will allow calibration of the distance scale of these old stars with much greater precision than is now available. Graduate and undergraduate students will be involved in all aspects of the program. Trigonometric parallaxes of nearby stars are fewer in number and lower in precision than is generally perceived. Beyond the Solar System, the distances to even the nearest stars are surprisingly poorly known. All but a few percent of published parallaxes are of stars so distant that the parallax method is inapplicable. 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. Dr. Upgren's program has made use of the increases made possible in precision in obtaining parallaxes and proper motions since 1967. His is one of the two most extensive such programs now active.