The transformed ﹩\mathop{e}\limits^{\rightharpoonup }﹩ and ﹩\mathop{I}\limits^{\rightharpoonup }﹩ vectors in frequency space for Asteroid (46) Proserpina before (top panels) and after (bottom panels) filtering. In the top panels, vertical lines indicate forcing frequencies from the seven planets included in the simulation as well as the peak proper frequency of the asteroid itself. Peaks corresponding to these frequencies are removed by the filter, as desired for the computation of proper elements. In the bottom panels, the proper terms corresponding to the free motion of Proserpina are shown; these terms are preserved in our filtering. There are many additional linear and nonlinear forced terms that are also handled that are not shown explicitly in this figure.