CCD Speckle Observations of Binary Stars from the Southern Hemisphere. III. Differential Photometry

Two hundred seventy-two magnitude di†erence measures of 135 double star systems are presented. The results are derived from speckle observations using the Bessel V and R passbands and a fast readout CCD camera. Observations were taken at two 60 cm telescopes, namely the Helen Sawyer Hogg Tele- scope, formerly at Las Campanas, Chile, andthe Lowell-Tololo Telescope at the Cerro Tololo Inter- American Observatory, Chile. The d ata analysis methodis presentedand , in comparing the results to those of Hipparcos as well as to recent results using ad aptive optics, we Ðndvery goodagreement. Overall, the measurement precision appears to be dependent on seeing and other factors but is generally in the range of 0.10È0.15 mag for single observations under favorable observing conditions. In four cases, multiple observations in both V and R allowedfor the d erivation of component V (R colors with uncertainties of 0.11 mag or less. Spectral types are assignedandpreliminary e†ective temperatures are estimatedin these cases.