  Certain forms of Lorentz violation in the photon sector are difficult to
bound directly, since they are "vacuum orthogonal," meaning they do not change
the solutions of the equations of motion in vacuum. However, these very same
terms have a unique tendency to contribute large radiative corrections to
effects in other sectors. Making use of this, we set bounds on four previously
unconstrained $d=5$ photon operators at the $10^{-25}$-$10^{-31}$ GeV$^{-1}$
levels.
