Sixth Catalog of Orbits of Visual Binary Stars

Stephen J. Williams, William I. Hartkopf & Brian D. Mason

U.S. Naval Observatory, Washington, DC

(last catalog update : Tue Aug 14 13:00:40 EDT 2018 )

This catalog continues the series of compilations of visual binary star orbits previously published by Finsen (1934, 1938), Worley (1963), Finsen & Worley (1970), Worley & Heintz (1983), and most recently by Hartkopf, Mason, & Worley (2001) in their Fifth Catalog of Orbits of Visual Binary Stars. That catalog, containing orbits published through 1 January 2001, was one of four double star catalogs maintained at the USNO that were written to CD-ROM in 2001 and distributed. The 30 June 2006 edition of the Sixth Catalog was included on the second USNO Double Star CD-ROM, which is available upon request. The Fifth Catalog was removed from the web in August 2007, as it had long been supplanted by the Sixth Catalog.

As of the above date, the Sixth Catalog included 2869 of 2782 systems (from a "master file" database currently containing 8819 orbits). All orbits have been graded on a 1 - 5 scale, as in earlier catalogs; the grading scheme has been modified, however, as described below. Ephemerides are included for all orbits with complete elements, as are plots including all associated data in the current Washington Double Star database.

2005 Mar: The format of the catalog was extensively modifed. A description of the new format is given here.

2007 Aug/Sep: Orbit catalog notes were merged with those of the Washington Double Star Catalog and later the Fourth Interferometric Catalog, in order to create a common notes file (and file format) for all USNO double star catalogs. Cleanup of old notes is never really completed, of course - we welcome notification of any errors you may run across.

2013 Aug: A version of the elements file was created which includes delimiters, for those users who work with SQL-type databases. This is a work in progress - please let us know of any problems with this file.

2013 Nov: A link was added to the "master file" database of all orbits. A few comments are in order. First, the grade (col. 244-246) is here a decimal; the range of grades is 0.0 - 5.5 (rounded to an integer value in the main catalog) and differences in grade of a few tenths are usually insignificant. A grade of 6.0 is given for orbits considered too old to be worth grading; vales of 7.0 are reserved for orbits with incomplete elements, values of 8.0 for interferometric orbits lacking rho/theta information; and values of 9.0 for astrometric orbits. Column 248 is a flag indicating a note, while column 250 is a yes/no flag indicating the solution considered currently "best".

2014 Sep: A new flag "m" was added for values of T0 expressed in modified Julian date. Although MJD (= JD-2,400,000.5) differs by only 0.5d from the truncated JD values (JD-2,400,000) flagged with "d", it was felt that a separate code for T0 values published in this unit would be less confusing than modifying published values for the catalog. 2015 Mar: The routine for generating ephemerides was extensively modified by George Kaplan (USNO), who converted it to double precision, with IAU expressions for Besselian epochs. This mainly affects those orbits with very short periods, resulting in changes to predicted theta values at the 0.1deg level or smaller. Also, separations for any set of ephemerides where the minimum value of rho is 0.01" or less are converted to mas; a flag "m" is added to the right of the last value. (Separations greater than 999" will similarly be converted to arcmin - with an "M" flag - although no such pairs are currently included in the catalog.) 2017 Sep: The routine for weighting individual measures was modified. All orbits were then regraded, and new figures were generated which included all measures in the WDS. The new weighting scheme is described in the "grading" section below.


* Please note: The frames version of the orbit catalog appears to be incompatible with some operating systems / browsers. Cavaeat emptor!

Your comments regarding either style or substance are welcome. Please inform the authors of any errors you run across in the catalog, as well as missing orbits, etc. We would also welcome notification (and/or copies) of any newly published elements.