C. Cucudumitrescu et D. Selaru, A MULTI-ANGLE AVERAGING THEOREM APPLIED TO THE J(2) PROBLEM, Celestial mechanics & dynamical astronomy, 69(3), 1997, pp. 255-270
A particular multi-angle averaging theorem for systems admitting a fin
ite Fourier expansion of the held is presented, together with its appl
ication to the problem of motion around an oblate planet (the J(2) pro
blem), in harmonic oscillator formulation. This method of approximate
integration has the advantage of working with (close on) directly meas
urable elements.