Cepheid-based distances to seven Type Ia supernovae ( SNe ) -host galaxies have been derived using the standard HST Key Project on the Extragalactic Distance Scale pipeline .
For the first time , this allows for a transparent comparison of data accumulated as part of three different HST projects , the Key Project , the Sandage et al .
Type Ia SNe program , and the Tanvir et al .
Leo I Group study .
Re-analyzing the Tanvir et al .
galaxy and six Sandage et al .
galaxies we find a mean ( weighted ) offset in true distance moduli of 0.12 \pm 0.07 mag – i.e. , 6 % in linear distance – in the sense of reducing the distance scale , or increasing H _ { \circ } .
Adopting the reddening-corrected Hubble relations of Suntzeff et al .
( 1999 ) , tied to a zero point based upon SNe 1990N , 1981B , 1998bu , 1989B , 1972E and 1960F and the photometric calibration of Hill et al .
( 1998 ) , leads to a Hubble constant of H _ { \circ } = 68 \pm 2 ( { random } ) \pm 5 ( { systematic } ) km s ^ { -1 } Mpc ^ { -1 } .
Adopting the Kennicutt et al .
( 1998 ) Cepheid period-luminosity-metallicity dependency decreases the inferred H _ { \circ } by 4 % .
The H _ { \circ } result from Type Ia SNe is now in good agreement , to within their respective uncertainties , with that from the Tully-Fisher and surface brightness fluctuation relations .