Maps of the dust optical depths on a log scale, in theIRAS100μm (first row left) and Planck- HFI bands at (first row right), (second row left), (second row right), (third row left), (third row right) and GHz (fourth row). All maps are shown in Galactic coordinates with the Galactic centre at the centre of the image. The missing data in all images correspond to theIRASgaps. The upper and lower bounds of the colour scale are set to τ_min = 5 × 10^-5 × (λ/100μm)^-1.8 and τ_max = 10^-2 × (λ/100μm)^-1.8 respectively.