Planck 353 GHz Stokes parameter maps of Musca (in MJy sr^-1). The total intensity map is at a resolution of 4.′8, while the Q and U maps are smoothed to a resolution of 9.′6 for better visualization. The crest of the filament traced on the I map is drawn in black (on the I and Q maps) and white (on the U map). The boxes drawn on the I map, numbered from 1 to 7, show the regions from which the mean profiles are derived (see Fig. 2).