Maps at different frequencies. Top panels: Westerbork Synthesis Radio Telescope 1.36 GHz images from Braun et al. (2007); the white ellipses show the synthesized beams; the contours show the same maps smoothed to the SRT 18.6 GHz resolution (HPBW = 57″) at surface brightness levels of 0.025, 0.1, 0.25, 0.5, and 0.75 MJy sr⁻¹. Bottom panels: Herschel 3 THz (100 μm) maps from DustPedia, with HPBW = 10″ (white circle); the contours show the maps smoothed to the SRT resolution, at 5, 20, 100, 250, and 500 MJy sr⁻¹. As a reference, the SRT images at 18.6 GHz are shown in the central panel (as in Fig. 1). The apertures adopted in our work are also shown.