THE HUBBLE DIAGRAM IN V FOR SUPERNOVAE OF TYPE-IA AND THE VALUE OF H-CIRCLE THEREFROM

The Hubble diagram for supernovae of Type Ia is derived in V and is summarized from the literature in m(pg) and in B. The ridge line equation of the diagram in V is log v220 = 0.2 m(v) + (0.653 +/- 0.012) from 34 SNe Ia. The dispersion of a single point about the ridge line is 0.36 mag. We argue from external evidence that the intrinsic dispersion is likely to be as small or smaller than sigma(v)(max) = 0.2 mag. The intrinsic (B - V) color at B maximum light is 0.09 +/- 0.04 mag. The calibration of the absolute magnitudes at maximum from four concordant methods, including the determination for SN 1937C via Cepheids in IC 4182, is [M(B)(max)] = -19.55 +/- 0.14 and M(V)(max) = -19.71 +/- 0.13. These values lead to the long distance scale with [H-0] between 45 and 52 km s-1 Mpc-1. This range depends on whether we use (1) the SN Hubble diagrams in the m(pg), B, and V bands themselves from Figure 1, or (2) the derived Virgo Cluster distance of 23.9 +/- 2.4 Mpc found from the SN 1937C calibration alone at M(V)(max) = -19.76, applied to the six SNe Ia with adequate V photometry that have appeared in the cluster with [V(max)] = 12.13 +/- 0.14. By the precepts previously developed for the Virgo velocity relative to the cosmic frame (Sandage & Tammann 1990; Jerjen & Tammann 1992), this Virgo distance gives the cosmic value of the Hubble constant to be H-0 = 47 +/- 5 km s-1 Mpc-1.