Astrometric Research in the Southern Hemisphere

Van Altena博士将继续他的南方固有运动（SPM）计划。这是第二个历元的观测，第一个历元的数据是在1965年到1974年间获得的，是在阿根廷埃尔莱昂西托的耶鲁南方天文台获得的。该项目的目标是确定恒星相对于微弱星系的绝对固有运动。这两个数据集20年的差异应该导致对固有运动的高度精确测量。绝对固有运动将用于确定RR天琴座恒星的绝对星等，对进动常数的修正，HIPPARCOS天文测量卫星的固定参考框架，奥尔特常数B，以及研究银河系的局部结构。与建立惯性参考系有关的问题已经困扰了天文学家数千年。随着时间的推移和测量技术的改进，人们发现星星在天空中并不是固定的，有必要把星星的运动和地球极点的运动分开。这种分离目前是通过观测太阳系的物体，如太阳、行星和小行星来实现的。然而，一些太阳系观测的模式与正常恒星观测的模式有很大的不同，这种差异可能会损害动态定义的参考框架和恒星框架之间的联系。结果，天文学家在银河系中留下了恒星流、运动群和非圆运动，使恒星运动模型和对进动常数修正的推导复杂化。确定暗星系固有运动的最初动机是确定进动常数的修正，从而改进基本星表系统。

Dr. Van Altena will continue his Southern Proper Motion (SPM) program. These are second epoch observations, the first epoch data were obtained between 1965 and 1974, which are taken at the Yale Southern Observatory at El Leoncito, Argentina. The goal of the project is to determine the absolute proper motions of stars with respect to faint galaxies. The 20-year difference in the two data sets should result in highly accurate measurements of proper motions. The absolute proper motions will be used to determine the absolute magnitudes of RR Lyrae stars, corrections to the constants of precession, a fixed reference frame for the HIPPARCOS astrometric satellite, Oort's constant B, and to study the local structure of the Galaxy. The problems associated with establishing an inertial reference frame have occupied astronomers for millenia. With the passage of time and improvements in measurement techniques, it was discovered that the stars are not fixed in the sky and that it is necessary to separate the motions of the stars from that of the Earth's pole. This separation is currently made through the observation of Solar System objects such as the Sun, the planets, and minor planets. However, some of the Solar System observations are made in modes that differ significantly from those used in normal stellar observatons, and this difference may compromise the connection between the dynamically defined reference frame and the stellar frame. As a result, astronomers are left with star streams, moving groups, and non-circular motions in the Galaxy to complicate the stellar motion model and the derivation of the corrections to the constants of precession. The initial impetus for determining proper motions with respect to faint galaxies was to determine the corrections to the constants of precession and thereby improve on the system of the fundamental catalogs.