In a separate paper (Freedman et al. 1997) details are reported on the impact of a Cepheid distance to Fornax specifically on the calibration and application of Type Ia supernovae to the extragalactic distance scale. Various calibrations dealing with interstellar extinction and/or decline-rate correlations are presented. Application to the distant Type Ia supernovae (Hamuy et al. 1995) gives H0 = 68 (± 8)r km/sec/Mpc.
Figure 38. A graphical representation of
Table 5 showing the various
determinations of the Hubble constant, and the
adopted mean. Each value of H0 and its statistical
uncertainty is represented by a Gaussian of unit area (linked dotted
line) centred on its determined value and having a dispersion equal to
the quoted random error. Superposed immediately above each
Gaussian is a horizontal bar representing the one sigma limits of the
calculated systematic errors derived for that determination. The
adopted average value and its probability distribution function (continuous
solid line) is the arithmetic sum of the individual Gaussians. (This
simple representation treats each determination as independent,
assuming no a priori reason to prefer one solution over another.)
Figure 39. Lines of fixed time representing
the theoretical ages of the oldest globular cluster stars are shown
for 12, 14 and 16 Gyr, plotted as a function of the expansion rate
H0 and density parameter 
0, for an
Einstein-de Sitter universe with the cosmological constant 
= 0. The thick
dashed horizontal line at H = 72 (±2)r
[±12]s km/sec/Mpc is the average value of the Hubble
constant given in Table 5. The
parallel (solid) lines on either side of that solution represent the
one-sigma random errors on that solution. Systematic errors on the
solution for H0 are represented by thin dashed lines
at 61 and 83 km/sec/Mpc. The only region of (marginal) overlap between these
two constraints is in the low density ( < 0.2) regime, unless
0. If the globular cluster ages
are assumed to place a lower bound on the age of the Universe,
the region of plausible overlap between the two solutions is more severely
restricted to even lower density models.