Comparison of our model results at quadrature phase α = 90° with literature values. Top panel: reflectivity f(90°). Middle panel: integrated quadrature polarization p(90°) of our model for the complete wavelength range (solid), and the results from the Pioneer 11 (⋄) and Voyager 2 (□) spacecrafts. The model results in the Pioneer 11 pass bands are also indicated (+). Bottom panel: integrated polarization flux p × f (90°).