Determination of the dynamical parameters of the Universe and its age

We determine the density parameters ${\mathrm{\Omega }}_m$ of gravitating matter and ${\mathrm{\Omega }}_{\mathrm{\Lambda }}$ of vacuum energy, by making a ${\chi }^2$ fit to nine independent astrophysical constraints. Paying rigorous attention to statistical detail, we find that the present best values are $\Omega_m=0.31\pm 0.07, \Omega_{\Lambda}=0.70\pm 0.13$,wherethese$1\sigma$ errors are approximately Gaussian (thus trivially convertible to whatever percentage confidence range desired). The total ${\chi }^2$ is 2.5 for 7 degrees of freedom, testifying that the various systematic errors included are generous. Since $\Omega_m + \Omega_{\Lambda}= 1.01\pm 0.15$, it follows that the Einstein-de Sitter model is very strongly ruled out, that also any low-density model with ${\mathrm{\Omega }}_{\mathrm{\Lambda }}=0$ is ruled out, and that a flat cosmology is not only possible, but clearly preferred. In the flat case we find $\Omega_m=0.31\pm 0.04$,fromwhichitfollowsthattheageoftheUniverseis$t_0 = 13.7^{+1.2}_{-1.1}(0.68/h)$ Gyr.