Relation between Herschel–Planck dust optical depth at 850 μm (τ₈₅₀) and dust extinction in K_S. The orange solid line is our linear fit with the slope γ = 3042 mag. The dashed orange line is the previous fit of Lombardi et al. (2014b, γ = 2640 mag) who used an extinction map based on 2MASS data. They also limited their fit to τ₈₅₀ < 2 × 10⁴, as indicated by the vertical dashed line, while we use the entire range displayed in this figure. We find a ~ 15% larger slope in the relation due to much better sampling of the cloud’s substructure.