The Extragalactic Distance Scale.

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 H0=Sl±S 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 /(Ω,Λ)~1·39±0.22. This value is only marginally consistent with an Einstein-de Sitter universe with Ω=0 and Λ=0, which has/=l. An Einstein-de Sitter universe with Ω=1 and A=0, for which /=2/3, appears to be excluded at the 3σ level. It is shown that some recent small values of Ho may have resulted from the large intrinsic dispersion in the linear diameters of galaxies, and from the fact that well-observed supernovae of Type la exhibit a luminosity range of -20 at maximum light. A representative sample of recent estimates of Ho is given in Table 1 . The median value of the Hubble parameter from the data in this table is H0=12 km s"1 Mpc"1, from which /(Ω,Λ)> 1.24. "See what is the breadth thereof, and what is the length thereof (Zachariah 2:2)