Comparisons of the numerical integration results of three systems ${\overline{H}}_{Schubart}$, ${\overline{H}}_{\text{Fourier}}$ and ${\overline{H}}_{\text{Normal}}$ In each frame, the initial condition corresponds to an equilibrium point (J_2e, ψ_2e = π) of the partial normal form ${\overline{H}}_n^{*}$ for a same parameter J₁ = −0.0179509. The normalization order is n = 1,…, 4 for frames (a)-(d). In each frame, the top panel shows the evolution of I₁,J₁, the second panel the evolution of ${\overline{P}}_2$,I₂,J₂, the third panel θ₁,ψ₁, the fourth panel ${\overline{Q}}_2$,θ₂,ψ₂, as marked by different curves.