  We define and compute the $L^2$ metric on the framed moduli space of circle
invariant 1-instantons on the 4-sphere. This moduli space is four dimensional
and our metric is $SO(3) \times U(1)$ symmetric. We study the behaviour of
generic geodesics and show that the metric is geodesically incomplete.
Circle-invariant instantons on the 4-sphere can also be viewed as hyperbolic
monopoles, and we interpret our results from this viewpoint. We relate our
results to work by Habermann on unframed instantons on the 4-sphere and, in the
limit where the radius of the 4-sphere tends to infinity, to results on
instantons on Euclidean 4-space.
