The opposition effect in Saturn's main rings as seen by Cassini ISS: 1. Morphology of phase functions and dependence on the local optical depth

► We used Cassini Saturn's rings images that exhibit the opposition spot. ► Phase functions were extracted for 211 locations in the main ring system. ► The opposition surge morphology is fit with a linear model and provides (A, HWHM, S). ► We found correlations with the morphological parameters and the ring optical depth. ► The correlation of S with the ring optical depth agrees with the shadow hiding.