  We analyze optical long-slit spectroscopy of the nucleus of M33 obtained from
the Space Telescope Imaging Spectrograph aboard the Hubble Space Telescope.
Rather than the steep rise expected within the radius of influence of a
supermassive black hole, the velocity dispersion drops significantly within the
inner parsec. Dynamical modelling yields an estimated upper limit of 3000 solar
masses for the mass of a central compact object. This upper limit is however
consistent within the uncertainties with the mass predicted by the M-sigma
relation, which is between 2000 and 20,000 solar masses. We therefore can not
conclude that the presence of a massive black hole in the nucleus of M33 would
require a different formation mechanism from that of the black holes detected
in galaxies with more luminous bulges.
