The Bull ’ s - Eye Effect as a Probe of Ω

We compare the statistical properties of structures normal and transverse to the line of sight which appear in theoretical N-body simulations of structure formation, and seem also to be present in observational data from redshift surveys. We present a statistic which can quantify this effect in a conceptually different way from standard analyses of distortions of the power-spectrum or correlation function. From tests with N–body experiments, we argue that this statistic represents a new and potentially powerful diagnostic of the cosmological density parameter, Ω. Subject headings: galaxies: distances and redshifts — large scale structure of the Universe