Theoretical atmospheric extinction curves for several sites including La Silla²⁷, Roque de los Muchachos²⁸, Paranal (Patat et al. 2011), and Muana Kea²⁹. We include a match to the Paranal extinction curve using α_λ = α_λ,Rayleigh + α_λ,Ozone + α_λ,Aerosol with b = −2, A₀ = 0.05 and H₀ = 1.5. It is difficult to fit the extinction curve as found at Muana Kea, likely due to high levels of volcanic dust.