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 la gives a Hubble constant of H0 = 45 +/- 9 km s-1 Mpc-1. The inverse Hubble time is 22 Gyr. If q0 = 1/2, the age of the universe would be 15 GHr, with a formal uncertainty of +/-20%.