Equation Icon  [ 1 ] 1[( ) 1 ] sωa = rΩa − r aa + -rSa + O (r2) Δ + -- 1 + rabΩb aa − r˙aa + -rRa0b0Ωb + O (r2) Δ2 [ 3] 2 3 + 1- ˙aa + O (r) Δ3 + O(Δ4 ), 3