The Washington Double Star Catalog (WDS) maintained
at the U.S. Naval Observatory by C.E. Worley and G.G. Douglass
is the principal database of astrometric double
and multiple star data for the astronomical community.
The WDS Catalog contains
positions (J2000), discoverer designations,
epochs, position angles, separations, magnitudes,
spectral types, proper motions, and, when
available, Durchmusterung numbers and notes for
the components of 78 100 systems based on 451 546
means. A new release is now available, WDS (1996.0),
and is a major
revision of the 1984.0 version.
The stars with Durchmusterung numbers
have been individually compared with the SIMBAD
database.
More precise
magnitudes (photographic and photoelectric), and
MK spectral types have been included where
available. The WDS Notes have been extensively
revised to include information on orbital motion
and multiplicity (including astrometric,
photometric, and spectroscopic), variability,
composite spectra, etc. For pairs with orbits, the
period, semi-major axis, and direction of motion
are given.
All stars with Durchmusterung numbers
have also been matched with the major astrometric
catalogs (ACRS, PPM, IRS, and FK5)
in order to provide
more accurate positions and proper motions. Since new
data are continually being added to the database,
the WDS is updated on a regular basis. Upon request,
and within our resources,
data from the Observation Catalog
(the data base of 
means comprising the WDS)
for individual
objects are supplied to professional and amateur
astronomers world-wide (e-mail to eqb@draco.usno.navy.mil).
The WDS is available from the data centers:
CDS, Strasburg, France
or
National Space Science Data Center at
NASA Goddard Space Flight Center
Greenbelt, MD 20771, U.S.A.
The WDS is also available on the World Wide Web at:
http://aries.usno.navy.mil/ad/wds/.
Acknowledgements
This research has made use of the Simbad database, operated at CDS, Strasbourg, France.