Electromagnetic perturbations of charged Kerr geometry

The freedom associated with infinitesimal co-ordinate transformations and infinitesimal tetrad rotations within the Newman Penrose formalism is used when considering electromagnetic perturbations of type D geometries. In particular, it is shown that for the charged Kerr geometry, a suitable choice of tetrad rotation leads to equations for the perturbed Newman Penrose components ₀ and ₂ which are closely related to those for the uncharged case.