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We present a measurement of the Hubble Constant based on Cepheid distances to27 galaxies within 20 Mpc. We take the Cepheid data from published measurementsby the Hubble Telescope Key Project on the Distance Scale (H0KP). We calibratethe Cepheid Period-Luminosity (PL) relation with data from over 700 Cepheids inthe LMC obtained by the OGLE collaboration; we assume an LMC distance modulusof 18.50 mag (d=50.1 kpc). Using this PL calibration we obtain new distances tothe H0KP galaxies. We correct the redshifts of these galaxies for peculiarvelocities using two distinct velocity field models: the phenomenological modelof Tonry et al. and a model based on the IRAS density field and lineargravitational instability theory. We combine the Cepheid distances with thecorrected redshifts for the 27 galaxies to derive H_0, the Hubble constant. Theresults are H_0 = 85 +/- 5 km/s/Mpc (random error) at 95% confidence when theIRAS model is used, and 92 +/- 5 km/s/Mpc when the phenomenological model isused. The IRAS model is a better fit to the data and the Hubble constant itreturns is more reliable. Systematic error stems mainly from LMC distanceuncertainty which is not directly addressed by this paper. Our value of H_0 issignificantly larger than that quoted by the H0KP, H_0 = 71 +/- 6 km/s/Mpc.Cepheid recalibration explains ~30% of this difference, velocity field analysisaccounts for ~70%. We discuss in detail possible reasons for this discrepancyand future study needed to resolve it.Comment: 33 pages, 8 embedded figures. New table, 5 new references, text  revision

A Determination of the Hubble Constant from Cepheid Distances and a Model of the Local Peculiar Velocity Field