Geoffrey G. Douglass

The 2001 US Naval Observatory Double Star CD-ROM. I. The Washington Double Star Catalog

The Washington Double Star Catalog (WDS), maintained by the US Naval Observatory, is the worlds principal database of astrometric double and multiple star information. The WDS 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 84,486 systems based on 563,326 means. The current version, available on-line, is updated nightly. This catalog is one of four USNO double star catalogs to be included on a new CD-ROM. A brief summary and statistical analysis of the contents of the catalog are presented.

Binary Star Orbits from Speckle Interferometry. I. Improved Orbital Elements of 22 Visual Systems

Improved orbital elements for 22 binary systems are presented. For 12 systems, masses are calculated using available trigonometric parallaxes and making certain assumptions regarding the mass ratio. For the other 10 systems, provisional elements are provided that should provide relatively accurate ephemerides for the next decade.

Speckle Interferometry at the US Naval Observatory. V.

The results of 1544 speckle interferometric observations of 637 binary stars, ranging in separation from 025 to 525, are tabulated. These observations were obtained using the 66 cm refractor at the US Naval Observatory in Washington, DC, with an intensified CCD detector. This is the fifth in a series of papers presenting measures obtained with this system and covers the period 1998 January 1 through December 31. Random errors for all measures are estimated to be 17.6 mas in separation and 055/ρ in position angle, where ρ is the separation in arcseconds.

Speckle Interferometry at the US Naval Observatory. IV.

The results of 1314 speckle interferometric observations of 625 binary stars, ranging in separation from 02 to 52 with a limiting secondary magnitude of V = 11, are tabulated. These observations were obtained using the 66 cm refractor at the US Naval Observatory in Washington, DC, with an intensified CCD detector. This is the fourth in a series of papers presenting measures obtained with this equipment and covers the period 1997 January 1 through December 31. Random errors for all measures are estimated to be 18 mas in separation and 057/ρ in position angle, where ρ is the separation in arcseconds.

Speckle Interferometry at the US Naval Observatory. II.

Position angles and separations resulting from 2406 speckle interferometric observations of 547 binary stars are tabulated. This is the second in a series of papers presenting measures obtained using the 66 cm refractor at the US Naval Observatory in Washington, DC, with an intensified CCD detector. Program stars range in separation from 02 to 38, with Δm ≤ 2.5 mag and a limiting magnitude of V = 10.0. The observation epochs run from 1993 January through 1995 August. Random errors are estimated to be 14 mas in separation and 052/ρ in position angle, where ρ is the separation in arcseconds. The instrumentation and calibration are briefly described. Aspects of the data analysis related to the avoidance of systematic errors are also discussed.

SYSTEMATIC EFFECTS IN ICCD-BASED SPECKLE INTERFEROMETRY OF DOUBLE STARS

Speckle interferometric observations of double stars enjoy considerably higher weight in orbital solutions than visual observations. This is justified on the basis of their higher precision and impersonal nature. It is crucial, therefore, that sources of systematic error in speckle observations are identified and controlled to a level commensurate with their low random errors. Accurate calibration is of primary importance. Other sources of systematic error that affect ICCD-based speckle interferometry include imperfect CCD charge transfer efficiency, fixed pattern noise, and nonuniform background in the autocorrelation function. All of these errors and their remedies are discussed. The restoration of observations compromised by fixed pattern noise is evaluated, and results for 30 such observations are given.

Systematic Errors in Double Star Observations

We have examined the visual and speckle observations of visual double stars made by 31 experienced observers in order to evaluate possible systematic errors in these series. Using 57 “definitive” orbits, we find no appreciable errors in position angle. We do find systematic effects in separation for some observers, and, in particular, a “proximity” effect for measurements of pairs closer than 0″.5. Root-mean-square residuals are:

Speckle Interferometry at the U. S. Naval Observatory

A new speckle interferometer began operation with the 66-cm refractor in Oct. 1990. The interferometer is an improved version of the one operated by CHARA at Georgia State University. We describe the instrument, its calibration, and first observational results.

Thirty Years of Work: Construction of the Washington Visual Double Star Catalog and Its Future

A new edition of the Washington Visual Double Star Catalog (1996.0) has now been completed and issued. This report discusses some of the back-ground concerning such compilations, their contents and arrangement of the data, as well as prospects for future enhancements.

The New Index Catalog of Visual Double Stars — WDS

A new index catalog of visual double stars, the Washington Double Star Catalog (WDS), 1984.0, is now available in tape form. All of the double star data has been updated, as well as the notes to the catalog. This report summarizes the contents of the WDS and describes its compilation.