Repeated imaging observations have been made of NGC 3627 with the Hubble Space Telescope in 1997/98 , over an interval of 58 days .
Images were obtained on 12 epochs in the F 555 W band and on five epochs in the F 814 W band .
The galaxy hosted the prototypical , “ Branch normal ” , type Ia supernova SN 1989B .
A total of 83 variables have been found , of which 68 are definite Cepheid variables with periods ranging from 75 days to 3.85 days .
The de-reddened distance modulus is determined to be ( m - M ) _ { 0 } = 30.22 \pm 0.12 ( internal uncertainty ) using a subset of the Cepheid data whose reddening and error parameters are secure .

The photometric data of ( ( Wells et al . ) ) ( 1994 ) , combined with the Cepheid data for NGC 3627 give M _ { B } ( { max } ) = -19.36 \pm 0.18 and M _ { V } ( { max } ) = -19.34 \pm 0.16 for SN 1989B .
Combined with the previous six calibrations in this program , plus two additional calibrations determined by others gives the mean absolute magnitudes at maximum of \langle { M _ { B } } \rangle = -19.48 \pm 0.07 and \langle { M _ { V } } \rangle = -19.48 \pm 0.07 ( Table 5 ) for “ Branch normal ” SNe Ia at this interim stage in the calibration program .

Using the argument by ( ( Wells et al . ) ) ( 1994 ) that SN 1989B here is virtually identical in decay rate and colors at maximum with SN 1980N in NGC 1316 in the Fornax cluster , and that such identity means nearly identical absolute magnitude , it follows that the difference in the distance modulus of NGC 3627 and NGC 1316 is 1.62 \pm 0.03 mag .
Thus the NGC 3627 modulus implies that ( m - M ) _ { 0 } = 31.84 for NGC 1316 .

The second parameter correlations of M ( max ) of blue SNe Ia with decay rate , color at maximum , and Hubble type are re-investigated .
The dependence of \langle { M { ( max ) } } \rangle on decay rate is non-linear , showing a minimum for decay rates between 1.0 < \Delta m _ { 15 } < 1.6 .
Magnitudes corrected for decay rate show no dependence on Hubble type , but a dependence on color remains .
Correcting both the fiducial sample of 34 SNe Ia with decay-rate data and the current eight calibrating SNe Ia for the correlation with decay rate as well as color gives H _ { 0 } = 60 \pm 2 ~ { } { ( internal ) } { km } { ~ { } s } ^ { -1 } { ~ { } Mpc } ^ { -1 } , in both B and V .
The same value to within 4 % is obtained if only the SNe Ia in spirals ( without second parameter corrections ) are considered .

The correlation of SNe Ia color at maximum with M ( max ) can not be due to internal absorption because the slope coefficients in B , V , and I with the change in magnitude are far from or even opposite to the canonical reddening values .
The color effect must be intrinsic to the supernova physics .
“ Absorption ” corrections of distant blue SNe Ia will lead to incorrect values of H _ { 0 } .

The Cepheid distances used in this series are insensitive to metallicity differences ( ( 53 ) 1999 ) .
The zeropoint of the P-L relation is based on an assumed LMC modulus of ( m - M ) _ { 0 } = 18.50 .
As this may have to be increased by 0 \fm 06 to 0 \fm 08 , all distances in this paper will follow and H _ { 0 } will decrease by 3 – 4 % .