  We present the first HST long-slit spectrum of a gaseous disk around a
candidate super-massive black-hole. The results of this study on the kinematics
of the gaseous disk in M87 are a considerable improvement in both spatial
resolution and accuracy over previous observations and requires a projected
mass of M_{BH}(sin i)^2 = (2.0+/- 0.5) 10^9 M_{sun} (M_{BH}=3.2 10^9 M_{sun}
for a disk inclination i=52deg) concentrated within a sphere whose radius is
less than 0.05" (3.5 pc) to explain the observed rotation curve. The kinematics
of the ionized gas is well described by a thin disk in keplerian motion. A
lower limit to the mass-to-light ratio of this region is M/L_{V}~110,
significantly strengthening the claim that this mass is due to the presence of
a central black-hole in M87.
