The Mass and the Mess in the Milky Way Halo

Our ability to measure the mass in the Galactic dark halo depends on
the precise knowledge of the density of old stars inhabiting
it. However, there seems to be little coherence in this distribution -
the Milky Way stellar halo appears to be dominated by
sub-structure. Yet there is hope. Using the freshly released SDSS DR8
data I will show how the shape of the stellar halo can be constrained
accurately and robustly. I will also show how tidal streams like the
one(s) from the Sagittarius dwarf can allow us to probe the shape of
the gravitational potential directly.