The Globular Cluster Systems in the Coma Ellipticals. I. The Luminosity Function in NGC 4874 and Implications for Hubble’s Constant

Abstract

We have used deep Hubble Space Telescope WFPC2 images in V (F606W) and I (F814W) to measure the luminosity distribution of the globular clusters in NGC 4874, the central cD galaxy of the Coma cluster. We —nd the ii turnover ˇˇ point of the globular cluster luminosity function (GCLF) to lie at V 27.88 ^ 0.12, while the overall GCLF shape matches the standard Gaussian-like form with disper- sion We use the GCLF as a standard candle by matching the turnover points in NGC p V 1.49 ^ 0.12. 4874 and another Coma elliptical, IC 4051, with those of the giant ellipticals in the Virgo cluster (M87 and —ve others). The result is *(m ( M) (ComaVirgo) 4.06 ^ 0.11 mag, which converts to a Coma distance d 102 Mpc if the Virgo distance modulus is