The Tip of the Red Giant Branch Distances to Type Ia Supernova Host
  Galaxies. III. NGC 4038/39 and NGC 5584
  We present the tip of the red giant branch (TRGB) distances to Type Ia
supernova (SNe Ia) host galaxies NGC 4038/39 and NGC 5584. Based on the deep
images constructed using archival Hubble Space Telescope data, we detect red
giant branch stars in each galaxy. VI photometry of the resolved stars and
corresponding I-band luminosity functions show the TRGB to be at I_{TRGB} =
27.67 \pm 0.05 for NGC 4038/39 and I_{TRGB} = 27.77 \pm 0.04 for NGC 5584. From
these estimates, we determine the distance modulus to NGC 4038/39 to be (m-M)_0
= 31.67 \pm 0.05 (random) \pm 0.12 (systematic) (corresponding to a linear
distance of 21.58 \pm 0.50 \pm 1.19 Mpc) and the distance modulus to NGC 5584
to be (m-M)_0 = 31.76 \pm 0.04 (random) \pm 0.12 (systematic) (corresponding to
a linear distance of 22.49 \pm 0.41 \pm 1.24 Mpc). We derive a mean absolute
maximum magnitude of SNe Ia of M_V = -19.29 \pm 0.08 from the distance
estimates of five SNe Ia (including two SNe in this study and three SNe Ia from
our previous studies), and we derive a value of M_V = -19.19 \pm 0.10 using
three low-reddened SNe Ia among the five SNe Ia. With these estimates, we
derive a value of the Hubble constant, H_0 = 69.8 \pm 2.6 (random) \pm 3.9
(systematic) km/s/Mpc and 72.2 \pm 3.3 (random) \pm 4.0 (systematic) km/s/Mpc,
respectively. The value from the five SNe is similar to those from the cosmic
microwave background analysis, and not much different within errors, from those
of recent Cepheid calibrations of SNe Ia. The value from the three SNe is
between the values from the two methods.
