The gravitational lens effect of the Virgo supercluster

We discuss the gravitational lens effect of the Virgo Supercluster, modelled by an axisymmetric, homogeneous ellipsoid. By numerical integration of the null geodesics we calculate the variation in the angular position and the brightness amplification ratio K of distant sources. The maximum angular displacement is found to be about 8 arcsec, occurring near the Supergalactic Poles. The maximum variation of K with respect to unity is about 3 10-4, occurring in the direction of Virgo, and corresponds to a negative amplification. The large-scale distribution of K in the celestial sphere is expanded in spherical harmonics, and its dipole and quadrupole amplitudes are found to be in magnitude about 6 10-5. All these effects are quite larger than the analogous ones calculated for the dark matter halo of our Galaxy