Panel a: ellipses used for estimating the inclination of the galaxy are given overplotted in its ‘final’ image. The red arrow points to the ellipse at 64″, which includes the spiral arms. Panel b: variation with radial distance of the PA. Panel c: variation with radial distance of the quantity i = cos⁻¹(b/a). The curve levels off in the outer parts at a value ⪆70°. The dashed lines point to distances of characteristic morphological features (see Sect. 3.3), while the two rightmost of them, which are coloured cyan, correspond to the two outermost drawn cyan ellipses in panel a.