Observed layers of the edge-on PDR in ρ Oph A. From left to right: H₂ 6.9 μm, O₂ 487 GHz, and H₂O 557 GHz are shown in red, green, and blue, respectively. Symbols are as in Fig. 1 and the region of H₂ observations is shown by the partial red polygon. The H₂ sources near (–100, 50) are gas shocked by HH-flows (see also Liseau & Justtanont 2009), and faint H₂ emission can also be seen from the VLA 1623 outflow. The white contours outline the integrated N₂H⁺ (3–2) emission, indicating the presence of dense gas above 10⁶ cm^-3 (Liseau et al. 2015, Paper I).