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The PPM catalogue contains the most complete and accurate information concerning positions, proper motions and some astrophysical data for practically all stars (about 379000) down to 10m‐11m over the whole sky. The systems and rms errors of the PPm positions, proper motions, stellar magnitudes and spectral classification are studied by comparison with catalogues of stellar characteristics and on the basis of the PPM data itself. The residual errors of stellar data in the PPM catalogue are small and/or they can be determined and eliminated.

Abstract. The present status of the Kyiv meridian axial circle after its refurbishment is described. The mounting of a new micrometer with the front-illuminated CCD 1040×1160 allows to observe stars up to V = 16 mag. For the stars of 11-14 mag, the internal positional accuracy of a single observation is 0.05-0.10 , and stellar V values are determined with an accuracy of 0.03-0.06 mag. The project of observations of star fields in the direction of 209 extragalactic radio-sources in declination zone 0+30 • is now in progress. The catalogue of positions, magnitudes and proper motions of secondary reference stars in regions with ICRF sources is expected to be compiled by 2003. Another project under way is a long-term astrometric survey of the equatorial zone to extend the Hipparcos-Tycho frame to fainter stars, and to measure their magnitudes and V − R colours.

A generalized equation was obtained for calculation of line profiles of solar formations in the assumption of their inhomogeneity. Line profiles of homogeneous formations are a particular consequence of this equation. Analysis of the equation and line profiles calculated from it was carried out.

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