  In theories with broken Lorentz symmetry, Cerenkov radiation may be possible
even in vacuum. We analyze the Cerenkov emissions that are associated with the
least constrained Lorentz-violating modifications of the photon sector,
calculating the threshold energy, the frequency spectrum, and the shape of the
Mach cone. In order to obtain sensible results for the total power emitted, we
must make use of information contained within the theory which indicates at
what scale new physics must enter.
