  We use numerical simulations to test the feasibility of the suggestion by
Ibata et al. (1994) that the excess population of stars which they discovered
in the Sagittarius region may be the disrupted remains of a dwarf spheroidal
galaxy. We find that a Fornax-like model for the pre-disruption system can
indeed reproduce the data. However, the galaxy must be on a relatively short
period orbit with a pericentre of about $10$ kpc and an apocentre of about $52$
kpc, giving a current transverse velocity of $255$ km/s and a period of $\sim
760$ Myr. Furthermore, disruption must have occurred predominantly on the last
pericentric passage rather than on the present one. The data are consistent
with transverse motion either towards or away from the Galactic Plane. These
results depend primarily on the rotation curve of the Galaxy and are
insensitive to the mass distribution in its outer halo or to the mass of its
disk.
