The Cepheid distance to IC 4182 - Calibration of MV(max) for SN IA 1937C and the value of H0

Cepheid variables with periods from 2 to more than 50 days have been found in IC 4182 from observations with the Hubble Space Telescope over a time interval of 47 days, comprised of 20 epochs. The period-luminosity relation from photometry of 27 Cepheids in the F555W HST magnitude system gives an apparent V distance modulus of (m - M)_AV_ = 28.47 +/- 0.08. The absolute magnitude of the type Ia supernova 1937C is M_V_(max) = - 19.92 +/- 0.13 from these data. Combining this with the Hubble diagram for SN Ia gives a Hubble constant of H_0_= 45 +/- 9 km s^-1^ Mpc^-1.