Total intensity images. Band 4 (∼145 GHz) is shown on the top panel, Band 7 (∼345 GHz) on the bottom panel. The thick black contour corresponds to 3 × σ_I, while the grey thin contours correspond to [5, 7, 10, 30, 100]×σ_I. The concentric circles overlaid on the images are the annular regions used for the noise analysis (see Sect. 2.5). The thick and dotted blue circles correspond to 1/3 of the HPBW and the full HPBW of the image, respectively. The red circles have as radii multiples of n * 1/3 of the HPBW, where n ranges from 2 to 5.