Intensity plots for different combination of lines fluxes (in 10-6 W m-2 sr-1) and ratios from the convolved maps. The different regions are indicated in the first panel and are labelled in the third, where blue represents points in front of the Bar and red behind the Bar. Plus symbols indicate points within the Bar(C ii). The square data point is the position where the cooling is calculated (see Sect. 7). The reference points for the adopted cut (Sect. 5) are plotted in circles and include error bars to give an indication of the uncertainties at different regions. In panels c) and g) the solid lines represent respectively a linear fit (y = −2.28 + 1.06x), and a polynomial fit for the fainter region outside the Bar (y = 6.37−1.53x + 0.12x2).