Comment on "Test of constancy of speed of light with rotating cryogenic   optical resonators"
  A recent experiment by Antonini et. al. [Phys. Rev. A {\bf 71}, 050101R 2005], set new limits on Lorentz violating parameters in the frame-work of the photon sector of the Standard Model Extension (SME), $\tilde{\kappa}_{e-}^{ZZ}$, and the Robertson-Mansouri-Sexl (RMS) framework, $\beta-\delta-1/2$. The experiment had significant systematic effects caused by the rotation of the apparatus which were only partly analysed and taken into account. We show that this is insufficient to put a bound on $\tilde{\kappa}_{e-}^{ZZ}$ and the bound on $\beta-\delta-1/2$ represents a five-fold improvement not a ten-fold improvement as claimed.   (For reply see Phys. Rev. A 72, 066102 (2005) DOI: 10.1103/PhysRevA.72.066102) 
Michael E. Tobar, Peter Wolf, Paul L. Stanwix