PREDICTED STAR COUNTS AND MEAN PARALLAXES DOWN TO THE 23RD MAGNITUDE

Star counts and mean parallaxes as a function of B, V, R magnitudes do wn to 23 are presented. The data were computed by the use of two funda mental equations of stellar statistics. The assumed model considers th e Galaxy as a symmetrical system with respect to its rotation axis and to its equatorial plane and as composed of the thin disk (main sequen ce and red giants), the thick disk and spheroid populations. Numbers o f stars and mean parallaxes were derived in bins of galactic longitude and latitude of 30 degrees and 10 degrees, respectively. For the comp utation of the mean parallaxes depending on Galactic coordinates and m agnitudes, series of products of Hermite and Legendre polynomials and of Fourier terms were used. The results of this paper may help in the planning of future survey missions and in the design of new telescopes . In addition, mean parallaxes can be used to derive corrections to ab solute parallaxes and proper motions for any position in the sky.