Of the stars whose primary is brighter than 16mv in the Washington Double Star Catalog (WDS), 3691 of them are found to either not exist or be 1.5mv different from otherwise similar stars in the AC2000, Bright Star, SAO, Tycho, or UCAC4 catalogs. A listing of these stars is to be found here.
From 2006 onwards, the Little Tycho Observatory has been conducting a visual survey of some of the brighter double stars in the northern sky. Occasionally stars in the WDS were not found. A search in other online sources also did not mention the stars, and a preliminary listing of these results was placed here.
This initial list is a small subset of the actual number of anomalies in the WDS data, the need for a more accurate and comprehensive study was apparent, and work commenced on it early in 2013.
The Tycho catalog is largely based on Hipparcos1 data.
The UCAC4 is the most recent astrometric catalog2. It accurately maps the sky to approximately 16mv.
The AC2000 is an older, but still useful astrometric catalog3.
The Bright star catalog4 and SAO5 are older, and well established catalogs that round out the survey, although no results were made based solely on their data.
These five catalogs are hearafter refered to as the "other catalogs", therby differentiating them from the WDS.
The WDS data was also checked with the General Catalog of Variable Stars (GCVS) and the New General Catalog (NGC), but the few matches found were not useful for this survey.
The 2MASS6 catalog was not used in this survey as the correlation between the infrared and visual magnitudes is not great enough to use it for a magnitude comparison.
Initially, all catalogs needed to be parsed by a series of programs written in Perl. The catalog data was put into a common format of 8 fields:
The fields represent:
This data is then parsed for each entry in the WDS. The initial parsing of the data considers only the stars in the other catalogs that are brighter than 12mv.
A second parsing of the data compares the WDS stars with the UCAC4 stars between 12-16mv. If the WDS primary is within 1.5mv and 2" of the UCAC4 star, the star will not be included in the final list.
The 16mv cutoff is because the limiting magnitude of the UCAC4 is 16.
The more stringent 2" error radius is applied here as both the WDS and UCAC4 claim sub arc second accuracy.
The error boxes were somewhat arbitrairly chosen:
The WDS stars are color coded:
Coordinates are all J2000. They are formatted such that they can be inserted into the "location" field of either Aladin or WikiSky to bring up the appropriate DSS image of the star's position.
A table of stars within 30" of the WDS position from the other catalogs can be accessed by by clicking the green Notes field in the listing. Any WDS Neglected Star and Notes associated with the star will be included as well.
Some stars are embedded in nebulosity, or are very near bright (< 5mv) stars and are not included in the astrometic catalogs, so they are included in this list. A search of the DSS plates7 reveals nebulosity or sometimes a very faint star in the given position. Examples:
3) AC2000 site
5) SAO site
6) 2MASS site
7) The STSCI DSS, WikiSky, or Aladin are good places to access this data.