Effective scattering cross section as a function of heliocentric distance measured in projected photometric apertures of different radii. The left panel shows the preperihelion data, and the right panel shows the postperihelion data. Symbols show the measured values, and dashed lines show power-law fits of the form ﹩{C}_{{\rm{e}}}={C}_{0}{r}_{{\rm{H}}}^{-\gamma }﹩. The numbers next to the fitted curves indicate the projected aperture radii in units of 10³ km.