THE PEAK BRIGHTNESS OF SN-1960F IN NGC-4496 AND THE HUBBLE CONSTANT

The light curve of the Type Ia supernova SN 1960F (in NGC 4496) is imp ortant because the Hubble Space Telescope has measured the distance to the host galaxy by means of Cepheid variables, and thus the Hubble co nstant can be derived. Important parameters in this derivation include the peak magnitude as well as the decline rate of the supernova. In t his Letter, I report on the results of my quantitative light-curve tem plate fitting to all published data. These reported data are widely di screpant yet can be made all consistent after the brightnesses of the comparison stars are brought onto the Johnson system. I find the peak B and V magnitudes to be 11.77 +/- 0.07 and 11.51 +/- 0.18. The declin e rate of SN 1960F is Delta m(15) = 1.06 +/- 0.08. These values can th en be used to derive the Hubble constant as soon as the distance modul us to NGC 4496 (mu) is measured, where the H-0 equals 50 km s(-1) Mpc( -1) 10(0.2[(31.58 +/- 0.13)-mu]). With the recent report from A. Saha that mu = 31.1 +/- 0.1, I find H-0 = 62 +/- 5 km s(-1) Mpc(-1). A revi ew is presented of 10 Type Ia events from which an average Hubble cons tant of 55 +/- 3 km s(-1) Mpc(-1) is found.