We use simulations to study the growth of a pseudobulge in an isolated thin exponential stellar disc embedded in a static spherical halo. We observe a transition from later to earlier morphological types and an increase in bar prominence for higher disc-to-halo mass ratios, for lower disc-to-halo size ratios, and for lower halo concentrations. We compute bulge-to-total stellar mass ratios B/T by fitting a two-component Sérsic-exponential surface-density distribution. The final B/T is strongly related to the disc’s fractional contribution fd to the total gravitational acceleration at the optical radius. The formula B/T = 0.5 fd1.8 fits the simulations to an accuracy of 30%, is consistent with observational measurements of B/T and fd as a function of luminosity, and reproduces the observed relation between B/T and stellar mass when incorporated into the GALICS 2.0 semi-analytic model of galaxy formation.

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Abstract. About 45 000 absolute and semi-absolute observations of right ascension of the FK4 stars were obtained during [1963][1964][1965][1966][1967][1968][1969][1970][1971][1972]. The observations were made with the three instruments of the Cerro Calan Observatory jointly by Chilean and Soviet astronomers. As a result, systematic A(x d cos8 errors were found to exist in the FK4 catalogue. For the reduction of star observations according to the SRS program, it is necessary to derive the system of the AOL corrections for the FK4.

Modern computing techniques are widely used in astrometry for reduction of astrometrical observations, theoretical studies and for gathering and storing measurements and observational data. At present the Pulkovo Observatory has a 3rdgeneration Soviet-Bulgarian computer ES-1020. It is similar to IBM computers in programming languages, magnete tapes, punch-cards and formats. ES-1020 can be used for a single-program and concurrent processing because it is supplied with a disc operating system(DOS). As its components DOS has the following translators: ASSEMBLER, BASIC, FORTRAN IV, PL/1, COBOL, etc., and also a programming library of mathematical and astrometrical modules. The library of sub-routines has a module principle which permits changing its contents and including new modules, e.g. astronomical programs.