The Allegheny Observatory trigonometric parallax program utilizes some of the most accurate equipment of its kind to determine very high precision parallaxes and masses for astrophysically interesting objects within 250 parsecs of the Sun. The program has sufficient precision to obtain reliable trigonometric distances of such luminosity standards as nearby star clusters, giant stars, and variable stars; to define portions of the mass-luminosity relationship previously outside of the domain of trigonometric techniques; and to detect low mass orbiting nearby stars. The determination of stellar parallaxes is of fundamental importance to almost all areas of astronomy, since the determination of many physical parameters requires knowledge of distance. The limitation in parallax determination up until quite recently has been the presence in most astrometric systems of systematic errors that limit the true accuracy of the determined distances. All indications are that efforts at the Allegheny Observatory have successfully rectified this problem. The development phase of Dr. Gatewood's program is now complete, and production observing is proceeding.
