The Implicit Metric on a Deformation of the Atiyah-Hitchin Manifold

Using twistor methods we derive a generating function which leads to the hyperk\" ahler metric on a deformation of the Atiyah-Hitchin monopole moduli space. This deformation was first considered by Dancer through the quotient construction and is related to a charge two monopole configuration in a completely broken SU(3) gauge theory. The manifold and metric are the first members of a family of hyperk\" ahler manifolds which are deformations of the $D_k$ rational singularities of $C^2$.