The sensitivity of the 2Dust model output to optical depth. The SAGE Epoch 1 photometry for LPV 28579 is allowed a 3σ variation (magenta error bars), and the spectroscopy is kept to within 1σ (gray curves). Model SEDs for 11.3 μm optical depth values spanning this range of allowed fluxes are also shown. The optical depth for good fits ranges from 0.26 (blue curve) to 0.29 (red curve). The best-fit curve for τ = 0.28 (green) is also shown for comparison.