Fig. A.1. Map in the line of [Ar II ] at 7.0 µm (contours) superimposed on the map of the [Ar III ] 9.0 µm line (grey scale spanning 0.01 to 0.05 erg s^-1 cm^{- 2} sr^-1). The contours for [ArII] are from 10^-3 to 10^-2 erg s^{- 1} cm^-2 sr^-1 by steps of 10^-3. The position of Ori A is indicated by a cross. The peak at 7 µm at this position is probably due to the S(5) line of H₂ rather than to [Ar II ] (see text).