Observations of HIPPARCOS double stars with the WIYN telescope

A program of follow-up observations of HIPPARCOS Double Stars has be en started using the WIYN 3.5-m Telescope at Kitt Peak, Arizona. Observations are made with the recently completed RYTSI speckle camera, which is capable of determining reliable magnitude difference at various wavelengths down to the diffraction limit of the telescope. Thus in addition to precise relative astrometry, component magnitudes and colors can be obtained in a survey mode for all systems observed. Preliminary results and system capabilities are described. The benefits of a sustained program of observations of the HIPPARCOS Double Stars include populating the mass-luminosity relation with many more points (once the orbital status of these, stars is known and orbital parameters are determined in sufficient detail for gravitationally bound pairs), robust tests of stellar evolution calculations in cases where at least one. component has evolved off the main sequence, and a more complete picture of the nearby field binary population.