The deceleration of nearby galaxies

For the Virgo complex the mean density excess in a sphere centred on Virgo, the weak velocity perturbation of the Local Group relative to Virgo and the deceleration parameter are derived. The method of treating the observational selection effects and the inability of the luminosity classification to significantly reduce the scatter in intrinsic luminosities are discussed. The density structure is described and the gravitational field calculated. The velocity field is determined, the mass normalization of the gravitational field fixed and the deceleration parameter derived. (C.F.)