Lensing reconstruction from PLANCK sky maps: inhomogeneous noise
  We discuss the effects of inhomogeneous sky-coverage on CMB lens
reconstruction, focusing on application to the recently launched Planck
satellite. We discuss the mean-field which is induced by noise inhomogeneities,
as well as three approaches to lens reconstruction in this context: an optimal
maximum-likelihood approach which is computationally expensive to evaluate, and
two suboptimal approaches which are less intensive. The first of these is only
sub-optimal at the five per-cent level for Planck, and the second prevents
biasing due to uncertainties in the noise model.
