map. τ₂₅₀ is derived from Herschel maps. τ₂₅₀ map is convolved to the same 60 resolution as map. Areas where τ₂₅₀ < 0.0003 are masked. Contours for 4, 3, 1.5, and 0.75 are marked with red line. Contours for τ₂₅₀ = 0.0052, 0.0039, 0.0019, and 0.0010 are marked with black line.