Spectral energy distributions of the best model of PDS 453 with and without foreground extinction (solid black line with AV = 1.9 mag and dashed brown line, respectively). The SEDs of the same model viewed pole-on are shown with and without the same visual extinction (solid blue line and dashed red line, respectively). The upper limits are indicated with downward-pointing arrows (see Sect. 4 for a description of the models).