CO line maps, starting from the J = 38−37 transition at 69 μm in the upper left corner to J = 14−13 at 183 μm at the lower right panel. The J = 23−22 map is blended and dominated in the central and northwest regions by the 4₁₄ − 3₀₃ o-H₂O line. The yellow cross indicates the position of the protostellar source and the dashed circles in the lower left panel delineate the three extraction regions for which excitation diagrams are constructed (see Sect. 4.1).