1996PASP..108.1091V

Cepheid variables are used to derive a Virgo cluster distance of 16.0 ± 1.5 Mpc. In conjunction with the mean Coma radial velocity and the well-established Coma/Virgo distance ratio, this yields a Hubble parameter H_0 = 81 ± 8 km s^-1 Mpc^-1. By combining this value with an age of the Universe ≳ 16.8 ± 2.1 Gyr, that is derived from the metal-poor globular cluster M92, one obtains f (Omega, Lambda) ≳ 1.39 ± 0.22. This value is only marginally consistent with an Einstein-de Sitter universe with Omega = 0 and Lambda = 0, which has f =1. An Einstein-de Sitter universe with Omega = 1 and Lambda = 0, for which f = 2/3, appears to be excluded at the 3-sigma level. It is shown that some recent small values of H_0 may have resulted from the large intrinsic dispersion in the linear diameters of galaxies, and from the fact that well-observed supernovae of Type Ia exhibit a luminosity range of ∼20 at maximum light. A representative sample of recent estimates of H_0 is given in Table 1. The median value of the Hubble parameter from the data in this table is H_0 = 72 km s^-1 Mpc ^-1 from which f(Omega,Lambda) ≳ 1.24.