Degree of linear polarization of Iapetus’ leading side in four Bessel filter bands, obtained after convolving the polarized spectra, versus the phase angle of observation. The data points were fitted by the trigonometric polynomial proposed by Lumme & Muinonen (1993): , where b and the inversion angle α₀ are considered as free parameters, while c₁ (affecting the position of the minimum) and c₂ (influencing the asymmetry of the curve) can be fixed to 0.5 and 0.35, respectively, for satellites (e.g., Belskaya et al. 2010). Note that we fitted all data points with the curve generated for the case of one spectral band (B band) to help see the spectral variation in the measurements in different filter bands.