Tracing the Magellanic Clouds Back in Time
  A solution is presented for the past motions of the Magellanic Clouds, the
Milky Way galaxy, and M31, fitted to the measured velocities of the Clouds and
M31, under some simplifying assumptions. The galaxies are modeled as isolated
bodies back to redshift about 10, when their velocities relative to the general
expansion of the universe were small, consistent with the gravitational
instability picture for the growth of structure. Mass outside the Local Group
is modeled as a third massive dynamical actor that is responsible for the
angular momentum of the Clouds. A plausible solution under these assumptions
requires that the circular velocity v_c of the Milky Way is in the range 200 to
230 km/s. The solution seems to be unique up to the modest variations allowed
by the choices of v_c and the position of the exterior mass. In this solution
the proto-Magellanic Clouds at high redshift were near the South pole of the
Milky Way (in its present orientation), at physical distance about 200 kpc from
the Milky Way and moving away at about 200 km/s.
