| Abstract | The turnover, or peak, magnitude in a galaxy's globular cluster luminosity function (GCLF) may provide a standard candle for an independent distance estimator. Here we examine the GCLF of the giant elliptical NGC 4365 using photometry of ~350 globular clusters from the Hubble Space Telescope's Wide Field and Planetary Camera 2 (WFPC2). The WFPC2 data have several advantages over equivalent ground-based imaging. The membership of NGC 4365 in the Virgo cluster has been the subject of recent debate. We have fit a Gaussian and t_5_ profile to the luminosity function and find that it can be well represented by a turnover magnitude of m^0^_v_ = 24.2+/-03 and a dispersion σ = 1.28+/-0.15. After applying a small metallicity correction to the "universal" globular cluster turnover magnitude, we derive a distance modulus of (m - M) = 31.6+/-0.3 which is in reasonable agreement with that from surface brightness fluctuation measurements. This result places NGC 4365 about 5 Mpc beyond the Virgo cluster core. For a V_CMB_ = 1592+/-24 km s^-1^ the Hubble constant is H_0_ = 72^+10^_-12_ km s^-1^ Mpc^-1^. We also describe our method for estimating a local specific frequency for the GC system within the central 5 h^-1^ kpc which has fewer uncertain corrections than a total estimate. The resulting value of 6.4+/-1.5 indicates that NGC 4365 has a GC richness similar to other early-type galaxies. |
