Distances of the Virgo and Coma clusters of galaxies through novae and supernovae

A distance modulus (m - M) ₀_ = 31. 30 +/- 0. 40 mag for the Virgo Cluster is estimated from our revised calibration of the maximum-magnitude versus rate-of-decline relation (Capaccioli et al. ) applied to the photometry of seven novae discovered by Pritchet and van den Bergh. The distance of the Coma (C) Cluster is then evaluated in units of the Virgo (V) Cluster distance, (mc_ - mᵥ_) = 3. 75 +/- 0. 20, by comparing the critically revised maximum-magnitudes for the Type Ia supernovae. From there, we derive a value of 70 +/- 15 km s^-1^ Mpc^-1^ for the Hubble constant and a Virgocentric infall velocity of 318 +/- 150 km s^-1^. This result is largely insensitive to the motions peculiar to the observer. Our analysis suggests that the extinction parameter, RB_= AB_/E (B-V), has a value as small as ~2 rather than the classical value ~4 and gives an average absolute maximum magnitude MB_ for the Type Ia SNs of -19. 2 +/- 0. 4.