2 Speckle-measurements

From August 1992 the speckle camera with the photon-counting television detector was used at the 6-m telescope during 5 observing runs for observations of 62 binary and multiple systems. 18 pairs from the list remained unresolved, mainly known as binaries from spectroscopy. In November 1994 observations of 21 stars were performed at the SAO 1-m telescope. In this data set 8 stars were not resolved. All the measurements with the 6-m aperture were made through the 600/130 nm bandpath window, while with the 1-m instrument the 600/200 nm filter has been used.

Information about the measurements is gathered in Cols. (1) to (6) of Tables 1 and 2. The first three columns list the Washington Double Star Catalogue number ([Worley & Douglass 1997]) or the epoch-2000 coordinate, the name of the star or its catalogue number in common use, and the discoverer designation. Column four lists the epoch of the observation in fractional Besselian year. Columns (5) and (6) contain the measured position angle $\theta$ in degrees and angular separation $\rho$ in milli-arcseconds. The note "UR'' stands for cases when the binary was not resolved. This might indicate or too close companions (less than 20 mas for the 6-m telescope, and 120 mas for the 1-m telescope), or too large magnitude difference (more than 3 magnitudes), or very bad seeing, or the combination of these factors. Most of unresolved at the BTA objects belong to spectroscopic binaries included into the program following the proposal of A. Tokovinin (private communication). In one case (BD+12$^\circ$4499 = GJ 1259), the position measurement is followed by the colons, indicating uncertain resolution which must be confirmed in the future.

The main component of the visual pair ADS 8861AB = GL 507AB was first resolved in 1993 - named here as BAG11. The system represents a couple of M-dwarfs orbiting around their mass center with a period of only 200 days. Because its spectrum shows the lines of both components ([Tokovinin 1997]), the binary becomes one of the promising new sources for the precise mass determination in the lower part of the HR-diagram.

Note that for new binaries resolved with the 6-m telescope here we follow the abbreviations already given in the Third Catalog of Interferomeric Measurements of Binary Stars ([Hartkopf et al. 1999]). To avoid possible mismatch in the discoverer designations of newly resolved pairs with the BTA telescope, we give their cross-identification in Table 3. In addition to the identification and coordinates is the year of first resolution and corresponding angular separation, followed by a first reference and notes.

For the BTA observations an accuracy of the position measurement is about 3 mas in $\rho$ and 2$^\circ$ in $\theta$, while the typical accuracy for the 1-m telescope is 8 mas in $\rho$ and 4$^\circ$ in $\theta$. Spatial calibration of the data was made by the observation of binaries with definitive orbits from the catalog of [Worley & Heintz (1983)] and other well-defined speckle binaries.

Acknowledgements

We thank A. Tokovinin from the Moscow State University for providing us with new "problem'' stars for speckle interferometry. Thanks are provided also to the Russian Federal Program "Astronomia'' and the 6-m Telescope Program Committee for their continued support of the double star program. This study has made use of the SIMBAD database, operated at CDS, Strasbourg, and the Third Catalog of Speckle Interferometric Measurements of Binary Stars, provided by the Georgia State University CHARA research group.