Epicyclic azimuthal advance
= Epicyclic azimuthal advance
{title2=$\Delta\psi=2\pi\Omega/\kappa$}
The azimuthal advance over one complete small radial oscillation is $\Delta\psi=2\pi\Omega/\kappa$. The oscillatory azimuthal correction averages to zero at first order. This angle compares successive radial turning points of the same type and describes <apsidal precession> when it differs from a full revolution.