GZK photon constraints on Planck scale Lorentz violation in QED

We show how the argument exploited by Galaverni and Sigl (2008 Phys. Rev. Lett. 100 021102 (see also 0708.1737)) to constrain Lorentz invariance violation (LV) using ultra-high-energy photon non-observation by the AUGER experiment can be extended to QED with Planck-suppressed LV (at O(E/M) and O(E2/M2)). While the original constraints given by Galaverni and Sigl (2008 Phys. Rev. Lett. 100 021102) happen to be weakened, we show that, when used together with other EFT reactions and the expected detection of photons at E > 1019 eV by AUGER, this method has the potentiality not only to basically rule out O(E/M) corrections but also to strongly constrain, for the first time, the CPT even O(E2/M2) LV QED.