Radial action of the spherical isochrone model
= Radial action of the spherical isochrone model
{title2=$J_r$}
For specific energy $E<0$ and specific angular momentum $L$,
$$
J_r=\frac{GM}{\sqrt{-2E}}
-\frac12\left(L+\sqrt{L^2+4GMb}\right).
$$
Consequently the Hamiltonian in actions is
$$
H(J_r,L)=-\frac{2(GM)^2}
{\left(2J_r+L+\sqrt{L^2+4GMb}\right)^2}.
$$