The evidence for the long distance scale with H_0<65

Abstract

The status of the determination of the Hubble constant is reviewed, setting out the evidence for the long distance scale with H_0=55+/-5. In parallel, various precepts said to favor the short distance scale with H_0>70 are discussed. The strongest evidence for the long scale are (1) the calibration of the peak absolute magnitude of type Ia supernovae with their Hubble diagram, (2) the distance to the Virgo cluster by six largely independent methods, and (3) field spirals binned by luminosity class. The three methods give H_0=56+/-3, 55+/-2, and 53+/-3 (internal errors). H_0 does not vary significantly over scales from 10-500 Mpc. Higher values of H_0 still in the literature are based on (1) an untenably small distance to the Virgo cluster, (2) an untenably large Virgo cluster velocity, (3) a questionable route through the Coma cluster, (4) an incorrect precept that the Cepheid distance to NGC 1365 gives the distance to NGC 1613, parent to two SNe Ia, calibrating them, (5) an unjustified reliance on planetary nebulae and surface brightness fluctuations as distance indicators, and (6) either an underestimation or a neglect of the importance of observational selection bias in flux-limited samples. There is no valid evidence for H_0>70. The status of the time scale test is reviewed. The result is 13-14 (+/-2) Gyr for the age of the Galactic globular cluster system. There is no time scale crisis provided that q_0<0.3, H_0=55, and Lambda=0.