Analysis of the polarised scattering brightness of the outer ring. Top: median radial brightness of the ring (yellow), as a function of the azimuth angle on the disk plane (0° is north), normalised to the maximum. Middle: residues of the data to the best-fit function, with grey arrows pointing towards the candidate shadow features. Bottom: IRDIS Qφ data transformed to polar-coordinates and corrected for the r² flux dilution, from which the median brightness of the top panel was extracted. The best-fit asymmetry parameter was g = −0.16 ± 0.01.