Surface brightness profiles along the major axis from SPIRE images (solid lines) and the corresponding models by Bianchi (2008) (dot-dashed lines) at 250 (top, blue, lines), 350 (middle, green, lines), and 500 μm (bottom, red, lines). We also show the profile for the model that includes dust heating from the EBL (dotted line, for 250 μm only). For each band, profiles are averaged over two beams perpendicular to the major axis. They are shown for flux densities  ≥1.2, 0.75, and 0.45 MJy sr^-1 for 250, 350, and 500 μm, respectively, corresponding to S/N > 3 for the average. Negative distances from the centre refer to the SW end of the galaxy. The optical size of the galaxy (; de Vaucouleurs et al. 1991) is indicated. See text for other details.