  Using the Hubble Space Telescope (HST) 37 long-period Cepheid variables have
been discovered in the Fornax Cluster spiral galaxy NGC 1365. The resulting V
and I period-luminosity relations yield a true distance modulus of 31.35 +/-
0.07 mag, which corresponds to a distance of 18.6 +/- 0.6 Mpc. This measurement
provides several routes for estimating the Hubble Constant. (1) Assuming this
distance for the Fornax Cluster as a whole yields a local Hubble Constant of 70
+/-18_{random} [+/-7]_{systematic} km/s/Mpc. (2) Nine Cepheid-based distances
to groups of galaxies out to and including the Fornax and Virgo clusters yield
Ho = 73 (+/-16)_r [+/-7]_s km/s/Mpc. (3) Recalibrating the I-band Tully-Fisher
relation using NGC 1365 and six nearby spiral galaxies, and applying it to 15
galaxy clusters out to 100 Mpc gives Ho = 76 (+/-3)_r [+/-8]_s km/s/Mpc. (4)
Using a broad-based set of differential cluster distance moduli ranging from
Fornax to Abell 2147 gives Ho = 72 (+/-)_r [+/-6]_s km/s/Mpc. And finally, (5)
Assuming the NGC 1365 distance for the two additional Type Ia supernovae in
Fornax and adding them to the SnIa calibration (correcting for light curve
shape) gives Ho = 67 (+/-6)_r [+/-7]_s km/s/Mpc out to a distance in excess of
500 Mpc. All five of these Ho determinations agree to within their statistical
errors. The resulting estimate of the Hubble Constant combining all these
determinations is Ho = 72 (+/-5)_r [+/-12]_s km/s/Mpc.
