AN ABSOLUTE CALIBRATION OF TYPE-IA SUPERNOVAE AND THE VALUE OF H(0)

I-band CCD photometry and K-band NICMOS photometry of the brightest red supergiants in IC 4182 (UGC 8188) are presented in order to estimate the distance to this galaxy. Assuming that the brightest red supergiants are "standard candles," and adopting an absolute calibration of the brightest red supergiants, we obtain a distance modulus of 27.0 +/- 0.2 mag (2.5 +/- 0.3 Mpc). This estimate is more than a magnitude closer in distance modulus than using photographic V-band photometry and a similar absolute calibration. Given this distance modulus we obtain M(B)(max) = - 18.8 +/- 0.34 for SN 1937C, with the primary uncertainty being due to extinction. From this calibration and the apparent magnitudes of well-observed Type Ia supernovae in E/SO members of the Virgo Cluster (<B(max)> = 11.9 +/- 0.1), we obtain a distance modulus of 30.7 +/- 0.36 mag (13.8 +/- 2.5 Mpc) for Virgo. This estimate is in excellent agreement with that obtained from the majority of modern techniques for estimating extragalactic distances. We conclude that one of the historical discrepancies in the estimated distance to the Virgo Cluster and in the extragalactic distance scale has been eliminated. With this result and the available data on more distant supernovae we obtain an estimate of the Hubble constant; namely H0 = 86 +/- 12 km s-1 Mpc-1. This result is further evidence for an apparent conflict in the value of H0 and the ages of globular clusters in an OMEGA = 1 universe.