HUBBLE-SPACE-TELESCOPE OBSERVATIONS OF GLOBULAR-CLUSTERS IN M87 AND AN ESTIMATE OF H-0

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 Delta(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.