  The usefulness of angle-action variables in galaxy dynamics is well known,
but their use is limited due to the difficulty of their calculation in
realistic galaxy potentials. Here we present a method for estimating
angle-action variables in a realistic Milky Way axisymmetric potential by
locally fitting a St\"ackel potential over the region an orbit probes. The
quality of the method is assessed by comparison with other known methods for
estimating angle-action variables of a range of disc and halo-type orbits. We
conclude by projecting the Geneva-Copenhagen survey into angle-action space.
