Introduction
The Washington Double Star Catalog (WDS) maintained by the USNO is the world's
principal database of astrometric double and multiple star data. 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 83,211 systems based on
500,129 means.
Changes in the Current Version
Changes due to Hipparcos:
The current edition of the WDS
contains the most recent, observational data available and includes systems
newly discovered by the Hipparcos satellite. While Hipparcos did not provide
discovery designations these are the primary system identifier in visual double
star astronomy. A cross reference file of these
3,406 systems containing the abbreviated coordinate, as well as the HDS and HIP
numbers is provided. A cross reference of WDS
entries which had Hipparcos problem solutions (i.e., the G, X, O, V double star
solutions as well as those which were suspected non-single) is also available.
Systems with only one measure in the WDS which are Hipparcos problem stars
(thus, providing a pseudo-confirmation) are indicated in the notes file.
Changes due to Tycho-2:
The current version of the WDS also
contains measures of 7,485 systems from the Tycho-2 Catalogue. These include
6,251 known systems from the Tycho-2 Catalogue as well as 1,234 newly determined
(TDS) systems from the Tycho-2 database. Photometric information has been
updated for systems not resolved by Hipparcos. Also, notes have been added for
2,757 systems of dubious veracity (N < 3) having a "failed double" or
"photocenter" solution.
The Delta-m Catalog:
Also, new to the WDS is an additional
indicator in columns 100-102. This ``D'' note code indicates the system has a
separate Delta-M determined (in addition to those determined during astrometric
measures). These results, primarily from Charles
Worley's Delta-m catalog plus other lunar occultation and interferometric
determinations will eventually be incorporated in a weighted scheme for the
magnitude listings of the WDS data line.
Discovery Designations Added:
The coordinates provided for
entries in the WDS are neither unique nor constant, and are therefore,
unsuitable to identify a system. Following the assignment of HDS designations to
systems first resolved by the Hipparcos satellite, an effort was made to assign
unique discovery codes to all other systems in the WDS. In some cases, two
different systems can have the same discovery code and number but different
components. Therefore, to uniquely identify a system it is necessary to include
the component field. Eight hundred twenty-two systems have had their discovery
number assigned by the USNO in this manner and are identified in the notes file.
Additional Information Available
Single Stars:
For observations of double stars it is often
necessary and beneficial to observe single stars. These can serve as an
idealized point-source-function (psf) to determine the behavior of various
elements in the optical chain, characterize various reduction algorithms, or can
be used to generate artificial double stars or other more complicated
morphologies by use of calcite crystals, slit masks, aperture masks, etc.
Unfortunately, finding a good list of these calibrator sources is easier said
than done. Generally speaking, the more stars are studied the higher their
multiplicity fraction. What is believed to be a good single star can render
vital calibration data useless through the discovery of a previously unknown
double star or the slight modification of the psf by an unresolved component.
The basic data for this list comes from the ``Third
Catalog of Interferometric Measures of Binary Stars'' (Hartkopf, W.I.,
McAlister, H.A., & Mason, B.D. 2000). In addition to publishing measurements of
double stars from speckle and Michelson interferometry, and lunar occultation
measures, this also contains results from various duplicity surveys (n = 3,632).
Selected stars from this catalog which are also found in ``The Bright Star
Catalogue'' (D. Hoffleit & W. Warren, 1992, Fifth Revised Edition,
preliminary) with a published null detection from a telescope with an aperture
greater than two meters are then considered (n = 1,769). This list is then of
bright stars which have no indication of duplicity by speckle interferometry.
Any of these objects which have measures by other techniques in the 3rd
Catalog (either interferometry or lunar occultation) are also excluded, as are
systems which have entries in this current version of the WDS.
Further, all of these systems were observed by the Hipparcos Satellite (ESA 1997,
The Hipparcos and Tycho Catalogues, ESA SP-1200), and they do
not have any double star solution (C, G, X, V, or O in field H59 of the main
catalogue) nor are they ``suspected non-single'' (S code in field H61).
The final all-sky list contains 1,170 systems
fulfilling these criteria.
ADS Stars:
Due to its continued use, a cross reference file
from the ADS to the WDS discovery designation and abbreviated coordinates is
provided here.
Multi-Commission Meeting on Stellar Designations:
The aim of
this meeting (scheduled for Thursday, August 10, 2000 during the XXIVth General
Assembly of the International Astronomical Union) is to develop a simple,
unambiguous, flexible, and computer friendly designation scheme for stellar
companions (including planets). The home page of the multi-commission meeting is
here.
USNO Double Star Publications
Recent results from the USNO double star program are available here. These papers present results from the
speckle measurement series, the orbit series, other refereed papers, as well as
oral and display presentations from meetings.
Concluding Remarks
Addition of the Delta-m information as well as other more significant changes
to the WDS database is currently under consideration. The input from regular
users of the database and other interested parties is greatly appreciated in our
efforts to make the WDS as helpful and user-friendly as possible. Please provide
comments on the format of the WDS, missed references, or any other items of
interest to you on our Comment form.
Information is being added to the database on a continuing basis, and this
edition of the WDS will also be updated regularly.
A preliminary version of the 5th Orbit Catalog to this site soon.
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.''
A notification of references to relevant papers is appreciated.
You may request a reasonable amount of
information from the double star catalog by e-mail.
This page is maintained by Brian Mason
Approved by F. Stephen Gauss, Astrometry Department, USNO
Updated: 28 January 2000
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