Note 404(1)

OK agreed on all points. The apsidal method is described by Marion and Thornton chapter seven of the third edition, and by Fitzgeradl on the university of Texas farside site. I used a combination of both sources.
Note 404(1)
To: Myron Evans <myronevans123>

In eqs. (16-17) the factor m seems to be missing at the LHS due to

f(r) = F(r)/m

but this is not important since the calculation proceeds with f(r) from (21) onwards. I find it a bit audacious to replace a constant (r_c) by a variable (r) in (29) but this seems to be the procedure having done for the apsidal angle calculation. Eq. (26) is obviously taken from the solution of the diff. eq.

x dot dot + omega^2 x =…

and comparing with (25). It follows that the negative of the expression in parentheses is a frequency. This is a bit difficult to guess for…