Characterization of Galactic extinction. Left: A_V as a function of Galactic latitude derived by converting SFD E(B − V) results using R_V = 3.1. The color excess (reddening) is E(B − V) = (B − V)_observed − (B − V)_intrinsic and R_V = A_V/E(B − V). The color bar adjacent to the right of the panel shows the fraction of the sky at A_V given in colors from the main plot. Within the range of the Euclid Wide Survey A_V ≪ 1. Right: The cumulative area where the SFD extinction is less than A_V or where the COBE/DIRBE 100 μm intensity (shown at 3 resolutions) is less than I_100 μm.