The Peak Brightness of SN 1960F in NGC 4496 and the Hubble Constant

The light curve of the Type Ia supernova SN1960F (in NGC 4496) is important because the Bubble Space Telescope has measured the distance to the host galaxy by means of Cepheid variables, and thus the Hubble constant can be derived. Important parameters in this derivation include the peak magnitude as well as the decline rate of the supernova. In this Letter, I report on the results of my quantitative light-curve template fitting to all published data. These reported data are widely discrepant 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 decline rate of SN 1960F is Δm15 = 1.06 ± 0.08. These values can then be used to derive the Hubble constant as soon as the distance modulus to NGC 4496 (μ) is measured, where the H0 equals 50 km s-1 Mpc-1 100.2(31.58±0.13)-μ. With the recent report from A. Saha that μ = 31.1 ± 0.1, I find H0 = 62 ± 5 kms-1 Mpc-1. A review is presented of 10 Type la events from which an average Hubble constant of 55 ± 3 km s-1 Mpc-1 is found. © 1996. The American Astronomical Society. All rights reserved.