Pulkovo Photographic Vertical Circle (PVC96) (Gontcharov+ 1998)

Details Pulkovo Photographic Vertical Circle (PVC96) (Gontcharov+ 1998) Pulkovo Photographic Vertical Circle (PVC96) (Gontcharov+ 1998)

Oct 1996

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1996ycat.1242....0g&link_type=abstract

VizieR On-line Data Catalog: I/242. Originally published in: 1998IzPul.213...48G

Mathematics

Logic

Positional Data, Meridian Observations

Scientific paper

The Pulkovo photographic vertical circle catalogue, the first version, PVC96, gives accurate declinations of 760 stars from the FK5 () and FK5 () Extension north of declination -15deg. In 1987-1995 the Photographic vertical circle of the Pulkovo observatory (PVC) carried out programme of observations of declinations of Mars, Jupiter and FK5 stars. Stars with declination higher than 45 deg were observed at both culminations. 8250 observations of 1345 stars and 49 ones of 2 planets have been treated and used to establish an instrumental coordinate frame conform to the DE200. The first version of the catalogue, PVC96, has been constructed on the basis of 6821 observations of 760 stars with at least 4 observations at upper culmination. For the stars with declination higher than 70 deg the observations at both culminations were used in the catalogue, for the rest of the stars only observations at upper culmination were used. The mean observational epoch is 1991.5. The internal mean error of one observation at zenith is 0.14 arcsec. The declinations of the stars are obtained with mean precision of 0.07 arcsec. The classical method of observations with vertical circle was used. Each meridian transit observation includes two exposures of 40 seconds each separated by a reversal of the entire instrument taking about one minute. During the period of the observations the PVC had a photographic-photoelectric micrometer including a photographic camera at the eyepiece end of the tube, and a special visual-photoelectric measuring machine. Readings of two divided vertical circles of glass were registered by photoelectric microscopes. A tilt of the instrument with respect to the vertical line was measured by two bubble levels. All the measuring devices of the PVC were calibrated and investigated externally (i.e., independently of observations). The flexure of the tube investigated at various zenith distances proves to be a function of zenith distance and temperature. The meteorological equipment was calibrated and the temperature, pressure and humidity were read to take refraction into account with a precision of 0.02 arcsec using the Pulkovo Tables, 5th edition. Since narrow red filters were used in the observations, the chromatic refraction was taken from the Pulkovo Tables also. All systematic errors (i.e., those depending on zenith distance) have been evaluated and taken into account with a precision at the level of 0.05 arcsec. Therefore the asymptotic accuracy of the observed declination after many observations has been evaluated as a function of zenith distance. Combining this asymptotic accuracy with formal precision of the obtained declination we evaluated the accuracy for every catalogue declination. The result of the stellar observations is an independent instrumental coordinate frame. Using the planetary observations this instrumental frame is rotated to conform to the DE200 ephemerides which are generally accepted as the best current conventional dynamical frame. It is done by solving for a correction to the equator zero-point derived from the observations of the planets made in the instrumental frame. The corrections to equator are: "instrumental frame minus FK5" (from stellar observations) = +0.014 +/-0.02 arcsec, "instrumental frame minus DE200" (from planetary observations) = -0.046 +/-0.03 arcsec, "catalogue PVC96 minus FK5" = +0.060 +/-0.04 arcsec. (1 data file).