Distances to Galaxies from the Correlation between Luminosities and Line Widths. III. Cluster Template and Global Measurement ofH0

The correlation between the luminosities and rotation velocities of galaxiescan be used to estimate distances to late-type galaxies. It is an appropriatemoment to re-evaluate this method given the great deal of new informationavailable. The major improvements described here include: (a) the templaterelations can now be defined by large, complete samples, (b) the samples aredrawn from a wide range of environments, (c) the relations are defined byphotometric information at B,R,I and K' bands, (d) the multi-band informationclarifies problems associated with internal reddening, (e) the templatezero-points are defined by 24 galaxies with accurately known distances, and (f)the relations are applied to 12 clusters scattered across the sky and out tovelocities of 8,000 km/s. The biggest change from earlier calibrations areassociated with point (e). Roughly a 15% increase in the distance scale hascome about with the five-fold increase in the number of zero-point calibrators.The overall increase in the distance scale from the luminosity--linewidthmethodology is about 10% after consideration of all factors. Modulo an assumeddistance to the Large Magellanic Cloud of 50 kpc and no metallicity correctionsto the Cepheid calibration, the resulting value of the Hubble Constant is H0 =77 +- 8 km/s/Mpc where the error is the 95% probable statistical error.Cummulative systematic errors internal to this analysis should not exceed 10%.Uncertainties in the distance scale ladder external to this analysis areestimated at 10%. If the Cepheid calibration is shifted from the LMC to NGC4258 with a distance established by observations of circum-nuclear masers thenH0 is larger by 12%.Comment: 34 pages including 15 figures and 1 table. One 14 page landscape table not encapsulated. Paper accepted for publication in Astrophysical Journa