Extinction law. The two red lines correspond to the cases described in Table 2 for A_V > 20 mag. The shaded area indicates the systematic error, for case B only, resulting from A_H/A_Ks uncertainty which can range from 1.52 (β = 1.6) to 1.60 (β = 1.8). At longer wavelengths than K_s, β = 1.6 gives larger A_λ/A_Ks. Diamonds are for A_V < 15 mag. The Weingartner & Draine (2001) model is plotted in gray with dashed and plain lines for R_V = 3.1 and R_V = 5.5, respectively. The axis scale is linear for x and logarithmic for y.