9312148 Van Altena This award will fund the construction of a Speckle Interferometer and station it at the Cesco Observatory of the Yale Southern Observatory and the University of San Juan at El Leoncito, Argentina. The purpose of this instrument is to rectify the large imbalance in the hemispheric distribution of modern observations of close visual binaries. The new observations, in combination with those from the pioneering work of Finsen, will lead to a significant improvement in the knowledge of the lower part of the mass luminosity relation. Improved masses can provide needed constraints to stellar structure and evolution calculations and their comparison with observations. ***
