Effective scattering cross-section as a function of the observation date for different apertures. The radius of each aperture, expressed in units 10³ km, is indicated next to the corresponding line. The dashed lines represent linear fits to the data points, with coefficients of determination (R²) of 0.59, 0.83, 0.35, 0.42, and 0.56 for the fits corresponding to apertures from smallest to largest, respectively.