Observed galaxy number counts on the lightcone up to second order: III.
  Magnification Bias
  We study up to second order the galaxy number over-density that depends on
magnification in redshift space on cosmological scales for a concordance model.
The result contains all general relativistic effects up to second order which
arise from observing on the past light cone, including all redshift and lensing
distortions, contributions from velocities, Sachs-Wolfe, integrated SW and
time-delay terms. We find several new terms and contributions that could be
potentially important for an accurate calculation of the bias on estimates of
non-Gaussianity and on precision parameter estimates.
