Sky distribution in Galactic coordinates (averaged over all distances) of the dust extinction parameters A₀ (middle) and R₀ (bottom). We indicate some molecular regions of our Galaxy by the rectangles in the top panel (overlay of the gray-scaled A₀ map). The maps are centered on the Galactic center, with longitudes increasing toward the left. We only plot the 60° centered on the Milky Way disk in these panels. Zoomed-in views of the highlighted regions are shown in Figs. B.4 and B.5.