Fig. B.1. Map of the 11.3 µm UIB (contours) superimposed on the 6.2 µm UIB map (grey scale from 0.05 to 0.3 erg s^-1 cm^{- 2} sr^-1). The contours correspond to integrated band intensities from 0.016 to 0.16 erg s^{- 1} cm^-2 sr^-1 by steps of 0.016. The distributions of the two UIBs are extremely similar. The position of Ori A is indicated by a cross.