Inner ring structures in galaxies as distance indicators. IV. Distances to several groups, clusters, the Hercules supercluster, and the value of the Hubble constant

The extragalactic distance scale derived in previous papers of this series from the diameters of inner ring structures (r) in galaxies is applied to the determination of the distances of six groups and clusters, and one supercluster, in the distance range 10< or =δ< or =112 Mpc. The clusters are well distributed on the sky and are used to derive a value of the Hubble constant free of the perturbing effects of the Local Supercluster. Several definitions of the Hubble ratio, for bound and unbound systems, and several frames of reference are introduced and used. Radial velocities V/sub c/ corrected for solar motion in a frame of reference defined by the nearby galaxies (2< or =δ< or =32 Mpc) are shown to yield a Hubble ratio which is substantially independent of direction. An analysis of four bound groups and one unbound grouping in the distance interval 10< or =δ< or =16 Mpc yields a mean Hubble ratio H/sub c/ = 92 +- 4 (internal m.e.) km s-1 Mpc-1. A similar analysis of two more distant bound systems, the IC 4329 Group at δ = 45 Mpc and the Hercules Supercluster at δ = 112 Mpc, yields H/sub c/ = 96 +- 5, or 93 +- 5 when plausible cosmological corrections are considered. The constancy of the Hubble ratio over the distance range 10< or =δ< or =112 Mpc gives no support to nonlinear concepts of the redshift-distance relation and demonstrates the absence of Malmquist bias in the μ0(r) scale. The value of the Hubble constant derived from the rings over this range is H0 = 93 +- 4 (internal m.e.) km s-1 Mpc-1 and +- 10 (external m.e.) when the zero point error of our tertiary indicators is included