Two hundred seventy-two magnitude difference 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 Telescope, formerly at Las Campanas, Chile, and the Lowell-Tololo Telescope at the Cerro Tololo Inter- American Observatory, Chile. The data analysis method is presented and, in comparing the results to those of Hipparcos as well as to recent results using adaptive optics, we find very good agreement. Overall, the measurement precision appears to be dependent on seeing and other factors but is generally in the range of 0.10-0.15 mag for single observations under favorable observing conditions. In four cases, multiple observations in both V and R allowed for the derivation of component V-R colors with uncertainties of 0.11 mag or less. Spectral types are assigned and preliminary effective temperatures are estimated in these cases.

Publication Date



© 2001 The American Astronomical Society.

We are grateful to R. Millis of Lowell Observatory and R. Garrison of the University of Toronto for their support of the speckle observations ; and S. Steele and F. Orrego Goya at Las Campanas and C. Enterline, O. Saa, and D. Maturana of CTIO for their help during the observing runs. William van Altena and Reed Meyer of Yale University also provided helpful comments. We thank the referee for a thoughtful reading of the manuscript and for suggested improvements.

This work was funded by two small grants from NASA administered by the American Astronomical Society and JPL Subcontract 1201846 from the Preparatory Science Program for the Space Interferometry Mission.

Note: imported from RIT’s Digital Media Library running on DSpace to RIT Scholar Works in February 2014.

Document Type


Department, Program, or Center

Chester F. Carlson Center for Imaging Science (COS)


RIT – Main Campus