Astrometric investigation of visual binaries at Pulkovo

Abstract

In the last 40 years the team headed by A.A. Kiselev at Pulkovo determined the orbits of 65 wide visual binaries and multiple stars. In most of the cases these studies are based on series of photographic observations made with the 26-inch refractor of Pulkovo observatory. Positional observations from Washington Double Star Catalog (WDS) were used for slowly moving star pairs. At the first stage of the preparation of Pulkovo Catalog of Orbits of Wide Pairs we compared the orbits of 53 of the 65 stars determined by our team with both the CCD observations made with the same telescope and the new WDS data. Our comparison based on 28 available sets of CCD observations demonstrated high quality of the data. No refinement is needed for most of the orbits (42 of the stars studied). The method of apparent motion parameters (AMP) allows determining the orbit if positional data are supplemented with information about the trigonometric parallax, component masses and radial velocities. HIPPARCOS parallaxes are available for only 201 of the 428 binary and multiple stars of the Pulkovo program. Once released, the results of GAIA mission may stimulate the determination of new orbits. In the future we plan to determine the orientation of the inferred orbits in the Galactic coordinate system and report the statistics of the orientation parameters.