Various overlays of PDR lines observed with PACS. The colour range for the PACS [C II] data (top left) is 20 to 211 K km s⁻¹, contours (1, 2, 3, 4 K km s⁻¹) of [N II] emission are overlaid. The colour range for the PACS [O I] 145 μm data (top right) is 0 to 85 K km s⁻¹, contours (10, 50, 90, 130, 170 K km s⁻¹) of PACS [O I] 63 μm emission are overlaid. The colour range for the PACS CO 13→12 data (bottom) is 0 to 16 K km s⁻¹, black contours (1, 4, 7, 11 K km s⁻¹) of PACS CO 16→15 emission, and grey contours (5 to 25 by 5 K km s⁻¹) of PACS CO 14→13 emission are overlaid. The ’finger’ of emission in CO 13→12 emission is probably an artefact since it is not visible in the CO 16→15 and 14→13 lines. The black triangle indicates the double system (Star A) of which at least one is a Herbig Be star, the white rectangle points to Star B with a B0.5 B1.5 spectral type, and the large black cross marks Star C, aresolved binary of which one is late O or early B star. The solid grey circle has a size of 20″ and the dashed one of 40″. This is the position for the flux determination for PDR modelling.