Map of the CO SLEDs used in this study. Each pixel in this map is equal in its physical size to one pixel in Fig. 1. The CO transitions (in W m^-2 sr^-1) observed by the SPIRE FTS from unmasked pixels in Fig. 1 are shown here in blue (detected, S/N> 1) or red (upper limits). The dynamical range for each plotted SLED is the same as in Fig. 9. CO transitions of J = 1 − 0,2 − 1,3 − 2 observed by ground-based telescopes are shown as black triangles. All SLEDs that contain at least 2 detections with the SPIRE FTS are fitted with RADEX to obtain the best-fit parameters. The black solid line shows the SLED that is described by the best-fit parameters in RADEX with its best-fit T_kin and n(H₂) labeled in each pixel, in units of K and cm^-3 respectively. The data contained in the five color–masked pixels are highlighted in Fig. 9 and discussed in Sect. 4.2.