2013MNRAS.430..546D

This paper updates the calibration of the cosmic distance scale by Cepheid variable stars making reference to a `geometric' Baade-Wesselink (BW) distance indicator which adopts pulsation linear radii and photometric angular diameters from period-radius and surface brightness relations, respectively, calibrated by fundamental data of Galactic Cepheids. The large number of fundamental-like BW distances (pulsation parallaxes) predictable for Cepheids by using the period and the (V, I) intensity mean magnitudes from HIPP photometry are then applied to calibrate the Galactic period-luminosity relations and the reddening-free Wesenheit relation in the (V, I) passbands well suited to obtain metallicity-corrected distance moduli µO = (18.486±0.047)mag or D = (49.80±1.10)kpc from Large Magellanic Cloud Cepheids of the Optical Gravitational Lensing Experiment map and µO = (29.281±0.051)mag or D = (7.18±0.17)Mpc from Hubble Space Telescope (HST) Cepheids in the inner field of the maser host galaxy NGC 4258, this value resulting in fair good agreement with the high-weight geometric water maser distance modulus. The Cepheid distance moduli of galaxies from the HST SN Ia Calibration Programme are found to be affected by significant systematic errors. Removing these errors leads to an upward revision of the Hubble constant at the value HO = (72.4±6.0) km/s/Mpc, in fair good agreement now with the result of HO = (72±8) km/s/Mpc originally derived in the HST Key Project Programme as well as with the most recent accurate determination of HO = (73.8±2.4) km/s/Mpc obtained by HST near-infrared observations of Cepheids.