Illustrations of the SED analysis. Top: wavelength shown horizontally and magnitude shown vertically. The black dots are the observations; they are partially visible because several coincide with red dots. Blue dots represent the chosen model i.e., the model with the SED that resembles best the SED of the observations. The chosen model plus dmag is in red. Diagram below: contours of the rms values. Vertically, A_K and horizontally τ_CSE (the values 5, 10, and 15 correspond to τ_CSE = 0.005, 0.20, and 6.5). The red point is at the location of the minimum rms (0.223). Contour levels are 0.5, 0.7, and 1.0.