Mission Statement for the Working Group on Maintenance of the Visual Double Star Database
The mission of the Working Group on Maintenance of the Visual Double Star Database and Catalogs
(henceforth WG) is to produce and systematically update databases and catalogs dedicated to visual
double and multiple stars, as specified in van de Kamp (1966IAUTB..12..267V). In 1964 the visual
double star database was transferred from Lick Observatory to the USNO, where it has remained. The
database and catalogs on visual double and multiple stars currently maintained at USNO include:
- The Washington Double Star database strives to maintain a complete and homogeneous record
of all published measurements of relative astrometry and photometry for visual double and multiple
stars deemed to be of sufficient quality (for a definition, see below) and/or historical or
astrophysical significance. As of 1 June 2013 the WDS database included over 1.2 million
observations of 125,765 double and multiple stars. The WDS summary catalog lists the measurements
of the first and last observation for every pair in the WDS database; a new summary is generated
from that database and posted to the web nightly.
- The Sixth Catalog of Orbits of Visual Binary Stars (ORB6) lists the currently most reliably
known orbits of each pair with a published solution. Published orbits exist for 2,406 WDS pairs (as
of 1 June 2013) and determining which one of possibly several published solutions is of highest
quality is done using an objective numerical grading scheme (described in the catalog text). ORB6
also includes ephemerides giving predicted positions for the next several years, orbital plots of all
WDS data on the calculated orbit, as well as a separate list of "calibration-quality" orbits which
may be adequate for most scale and orientation determinations.
- The Catalog of Rectilinear Elements (LIN1) lists astrometric solutions of rectilinear elements
for 1,311 pairs (as of 1 June 2013). While it is possible that some of these may be physical doubles
with a very long period and perhaps high eccentricity, most are likely optical pairs whose differential
proper motion can be linearly characterized. As double star observations have been made for a longer
time and often with greater frequency than classical astrometry techniques, many of these pairs have
differential proper motions determined to greater precision and accuracy than can be done by other
- The Fourth Catalog of Interferometric Measurements of Binary Stars (INT4) enumerates
all measurements of visual double stars made by high angular resolution techniques. These include
interferometry as well as adaptive optics, space observation, lunar occultation and other methods
enumerated in the catalog notes. Complete photometric information, when available, is also provided,
as are interferometric non-detections of single stars or unresolved pairs. These stars have been
examined for companions and no similar brightness pair has been found to the listed limit. Some
such "single stars" may then be appropriate for scale determination (with other equipment) or
point source characterization.
- The Third Photometric Magnitude Difference Catalog (DM3) lists all the measures of
magnitude differences, made by precise techniques, that are not included in the WDS. The magnitude
difference and the filter used for its measurement, can aid in the determination of a companion's
spectral type or colour index. If one or both of the components is/are variable, it may help to
characterize the type of variability.
Since they represent fundamental tools for studying long-term motions and possible dynamical interactions,
it is essential that catalogs be updated regularly and that members of the astronomical community, upon
request, be provided with all available data on pairs of interest. The USNO-based editors are charged
with instituting these updates and with providing information to the user in a timely manner.
It is however also essential that data entered into any of the catalogs be of a sufficient quality
to be of use in analysis of relative motions, duplicity surveys, and other studies. The editors will
work with those publishing relevant data to ensure that all necessary information is provided and
that any perceived errors are rectified if possible. The editors maintain the right to exclude data
from the catalogs if, after examination, they conclude that the data are of insufficient quality,
or are inconsistent with other data at such a scale that it may discredit the catalogue's utility
for scientific purposes.
It is expected that all day-to-day activities in maintaining these catalogs will remain under the
purview of the editors. The WG, however, may be called upon to lend their expertise in discussions
of major format change or other changes to any of the catalogs, and to help resolve any disputes which
may arise between authors and editors concerning nomenclature, rejected data, or equivalent matters.