We present the results of 3489 astrometric observations for 361 visual double stars performed in 2003–2007 with the 26-inch refractor of the Pulkovo Observatory. The angular separations between the components (ρ) and the position angles (θ) are given. The errors in these quantities are, on average, 0″.009 for ρ and 0°.40/ρ for θ, where ρ is the separation in arcseconds.

Astrometric CCD observations of visual double stars at the Pulkovo Observatory

We propose a form of a lens corrector at the prime focus of a hyperboloidal mirror that provides a flat field of view up to 3° in diameter at image quality D80<0.8 arcsec in integrated (0.32–1.1 µm) light. The corrector consists of five lenses made of fused silica. All lens surfaces are spherical in shape, so the system is capable of achieving better images, if necessary, by aspherizing the surfaces. The optical system of the corrector is stable in the sense that its principal features are retained when optimized after significant perturbations of its parameters. As an example, we calculated three versions of the corrector for the Blanco 4-m telescope at Cerro Tololo Inter-American Observatory with \(2\mathop .\limits^ \circ 12\), \(2\mathop .\limits^ \circ 4\) and \(3\mathop .\limits^ \circ 0\) fields of view.

A wide-field corrector at the prime focus of a Ritchey-Chrétien telescope

We present the results of 15184 astrometric observations of 322 visual binaries carried out in 2007–2014 at Pulkovo observatory. In 2007, the 26-inch refractor (F = 10413 mm, D = 65 cm) was equipped with the CCD camera FLI ProLine 09000 (FOV 12′ × 12′, 3056 × 3056 pixels, 0.238 arcsec pixel−1). Telescope automation and weather monitoring system installation allowed us to increase the number of observations significantly. Visual binary and multiple systems with an angular distance in the interval 1.ʺ1–78.ʺ6 with 7.ʺ3 on average were included in the observing program. The results were studied in detail for systematic errors using calibration star pairs. There was no detected dependence of errors on temperature, pressure, and hour angle. The dependence of the 26-inch refractor’s scale on temperature was taken into account in calculations. The accuracy of measurement of a single CCD image is in the range of 0.ʺ0005 to 0.ʺ289, 0.ʺ021 on average along both coordinates. Mean errors in annual average values of angular distance and position angle are equal to 0.ʺ005 and 0.°04 respectively. The results are available here http://izmccd.puldb.ru/vds.htmand in the Strasbourg Astronomical Data Center (CDS). In the catalog, the separations and position angles per night of observation and annual average as well as errors for all the values and standard deviations of a single observation are presented. We present the results of comparison of 50 pairs of stars with known orbital solutions with ephemerides.

Astrometric observations of visual binaries using 26-inch refractor during 2007-2014 at Pulkovo

We propose a form of a lens corrector at the prime focus of a hyperboloidal mirror that provides a flat field of view up to 3 ◦ diameter at image quality D80 < 0.8 arcsec in integrated (0.32- 1.10 µm) light. The corrector consists of five lenses made of fused silica. Only spherical surfaces are used, so the system is capable of achieving better images, if necessary, by aspherizing the surfaces. The optical system of the corrector is stable in the sense that its principal features are retained when optimized after significant perturbations of its parameters. As an example, three versions of the corrector are designed for the V.M.Blanco 4-m telescope at Cerro Tololo Inter- American Observatory with 2 ◦ .12, 2 ◦ .4, and 3 ◦ .0 fields of view. c 2004 MAIK "Nauka/Interperiodica".

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A wide-field corrector at the prime focus of a ritchey-chr ´

The optical layout of the T-170M telescope for observation of astronomical objects in the ultraviolet spectral range 0.115–0.35 μm from the spacecraft SPECTRUM-UV is described. The telescope represents a Ritchey-Chretien aplanat with an aperture 1.7 m in diameter, a relative hole of f/10, and a field of view of 0.5°. The spectrographs are designated for obtaining spectra of stars and spread objects with a resolution of 2000–50 000. It is planned to record direct images using two field cameras: a wide-angle (f/10) and a telefocus (f/75–f/100) camera. The tolerances for basic parameters and the characteristics of the optimal system of baffles and the optics control unit are given.

N. N. Mikhelson

Papers

Optical telescopes: Theory and design