SIMBAD references

Speckle observations are reported for 53 stars with composite spectra selected from the Michigan Spectral Catalogue in an effort to improve the orbits of known binaries and to discover new binaries among this class of objects. The data were obtained using the 1.3 and 2.4 m telescopes at the Michigan-Dartmouth-MIT Observatory and the Georgia Tech Research Institute speckle imaging system. For 50 stars in the sample for which no indication of duplicity was found in our data, we may place an upper limit of ≤0".2 on the separations at the epochs of observation. Three stars were resolved, including HD 26796, also discovered to be double by Hipparcos. A discussion of the accuracy of the measurements based on comparisons with speckle standard stars is presented.