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Double Star

Commission 26

Commission 26




(Hartkopf et al.)


Visual Orbits


Sample Washington Multiplicity Catalog

William I. Hartkopf & Brian D. Mason
U.S. Naval Observatory, Washington, DC

(last update: 19 June 2003)

The Washington Multiplicity Catalog (WMC) project is an effort to address often conflicting nomenclature schemes used by astronomers in different fields of double and multiple star research, by compiling a catalog of all known binary and multiple systems, then assigning a consistent (insofar as possible) component designation to each component. This effort was begun shortly before the 2000 IAU General Assembly in Manchester, UK. A sample version of the planned catalog was presented at IAU Colloquium 191, held in Merida, Mexico in February 2003, and a modified version of this sample will be presented at the July 2003 GA in Sydney, Australia. Finally, if the nomenclature and catalog format are agreed upon, a full-sky version of the catalog will be created in time for the 2006 GA in Prague.

A complete library of discussions, IAU resolution, etc. may be found on the WMC home page. A talk was given by one of the authors at the Merida meeting, outlining the history of the project and the current status of the WMC. A version of this Merida paper is also available.

The Sample WMC is comprised of doubles and multiples in the 11:00 - 11:30 hr band of right ascension, and combines visual systems from the Washington Double Star (WDS) database with spectroscopic, interferometric, occultation, astrometric, eclipsing, interacting, and other systems, both stellar and sub-stellar (e.g., extrasolar planets). A format and reference list describes the columns and lists the duplicity sources checked so far in the creation of the catalog.

Some modifications were made to the WMC following the Merida meeting - most notably the conversion of the WMC designation from arcminute to arcsecond precision. It should be noted, however, that not all planned modifications are complete:

  • Coordinate conversion: We discovered that IAU rules for coordinate-based designations require truncated coordinates, and furthermore that the coordinates themselves listed in a catalog should have one decimal place of precision more than the designation. We unfortunately initially used rounded values and kept only arcsecond-precision values for both designation and coordinates. Both these columns have now been updated.
  • Binary types: The WDS database includes a mixture of optical and physical pairs. The "V" code for visual pairs in the WMC are gradually being replaced with "Vp", "Vo", and "Vc" codes (for physical, optical, and common-proper-motion pairs, respectively) for systems where this additional bit of information can be determined (through Keplerian or rectilinear relative motion, for example).
  • Links: Links have been included to many of the source catalogs. The WDS summary catalog will require some changes in its web files to accomodate links to individual objects - this may have to await other anticipated changes in the catalog.

The main purpose of this sample catalog is to elicit suggestions and comments from the double star community: additional sources of duplicity information, columns of information which should be added or seem unnecessary, format suggestions, etc. Your comments are most welcome (and indeed, are necessary if the full version of this catalog is to be of use to the community). Please send your comments, suggestions, reports of errors, etc. to Thank you.

Table of Contents:

Sample Catalog
Cross Reference
Format and References
Merida paper
WMC home page

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