Comparison of Galactic extinction laws. Left: Galactic extinction laws as reported by Draine (2011) (red), Rieke & Lebofsky (1985) (green), and Savage & Mathis (1979) (blue). The solid, dotted, and dashed lines are the Cardelli et al. (1989) extinction law evaluated for R_V = 3.1, 2.75, and 5.30, respectively. Right: The same extinction laws are plotted normalized to the Draine (2011) extinction law to show that differences of several percent exist, and that variations of ≳10% can arise from R_V variations.