The Kinematics of the Outer Halo of M87

Radial velocities are presented for a new sample of globular clusters in the outer halo of M87 at a distance of 300''–540'' (24–43 kpc) from the center of this galaxy. These are used to augment our previously published data, and an analysis of the rotation and velocity dispersion of the M87 globular cluster system is carried out. The rotation is ~300 km s^(-1) at R = 32 kpc, at which point the velocity dispersion is also still quite high, ~450 km s^(-1). The high rotation is interesting. The outer halo of M87 is, as was found in our previous kinematic analysis, very massive