Maps of thermal dust emission I^sbg calculated for the Ν (H₂) = 3 × 10²³ cm⁻² filament model. Frame a corresponds to isotropic illumination with χ = 1, but the surface-brightness values are multiplied by 100 just for plotting (the same colour bar applies to all frames). The other frames include both the isotropic field and a point source located at Δy = 2.09 pc and at a distance of 0.93 pc in front, behind, or to the left of the filament centre axis (frames b, c, and d, respectively).