MBB optical depth estimates calculated for synthetic observations from RT models. The uppermost frames show the results of MBB fits with a single temperature component (β = 1.8 in frame a, β = 2.0 in frame b) relative to the actual optical depths in the model. The second row shows the corresponding ratios for MBB fits with Gaussian temperature distributions. The RT models (FWHM = 0.5 pc, A_V = 1^mag) used either the COM (frames a and c) or the CMM dust (frames b and d). The cyan contours are drawn at the values of 0.8, 0.9, and 1.0.