[ITAL]Hubble Space Telescope[/ITAL] Observations of Globular Clusters in M87 and an Estimate of [ITAL]H[/ITAL][TINF]0[/TINF]

Hubble Space Telescope observations of over 1000 globular clusters in the central region of M87 have been made using the Wide Field and Planetary Camera 2. The limiting magnitude in V is 26 mag, more than 2 mag beyond the turnover of the luminosity function. The distribution is well fitted by a Gaussian profile with a mean of ⟨ m V 0 ⟩ = 23.72 ± 0.06 mag and a width of 1.40 ± 0.06 mag. Assuming a value of ⟨ M V 0 ⟩ = -7.4 ± 0.25 mag for the globular cluster luminosity function results in a distance modulus of ( m - M ) = 31.12 mag to the Virgo Cluster. Using a value of Δ Coma-Virgo ( m - M ) = 3.71 ± 0.10 mag and adopting a velocity for the Coma Cluster of 7188 km s -1 result in a value for the Hubble constant of H 0 = 78 ± 11 km s -1 Mpc -1 . The V - I color distribution is bimodal, with peaks at V - I = 0.95 mag and 1.20 mag. The mean size of the clusters is R eff = 3 pc, with a scatter of 1 pc.