The Washington Visual Double Star Catalog, 1996.0

These latter are the result of a continuing project to build a truly comprehensive and complete data base. Thus, approximately 452000 individual means, representing over a million individual observations, form the basic material from which the WDS is constructed. We have not included a small amount of data because of unresolved questions concerning it.

The WDS contains 78100 double stars, counting, as did the IDS, multiple components in the same system as separate pairs. Comparison of the present catalog with its IDS predecessor will reveal that a considerable number (about 1000) of previously catalogued objects have been removed from the WDS in the process of editing the data. The most common reason for removal is that the object is not certainly double.

We wish to emphasize that the WDS is not intended to be an "astrometric" catalog in the sense usually employed, but rather is to be considered a finding list for observers, as well as serving as a notification of which objects are known doubles or multiples, along with some basic astrometric and astrophysical parameters. In addition, the WDS offers information on the amount of motion and frequency with which a given object has been observed, which is sufficient, in fact, to provide a basis for the construction of observational programs.

Finally, the data can be used (with proper precautions) to analyze certain statistical properties of visual double stars. Of course, as has been true for many years, the individual measures of specific objects are available and will be supplied to requesters provided that the amount of data desired is reasonable. Request for Acknowledgment: If the WDS and associated databases were helpful for your research work, the following acknowledgement would be appreciated: ``This research has made use of the Washington Double Star Catalog maintained at the U.S. Naval Observatory.''