Colour-colour plots for different regions across Nest200047 and over different frequencies. The top row shows ${\alpha }_{53}^{144}$ vs ${\alpha }_{400}^{815}$ and ${\alpha }_{53}^{144}$ vs ${\alpha }_{815}^{1518}$ for regions D2 (magenta points), C1/C2 (blue points), B1/B2 (cyan points), and A (yellow points). Images at 12 arcsec resolution were used for the measurements. The boxes used (one-beam area for region A and three beam-area for the other regions), colour-coded according to the different regions, are shown in the top left panel. The middle row shows ${\alpha }_{53}^{144}$ vs ${\alpha }_{144}^{400}$ (middle) and ${\alpha }_{53}^{144}$ vs ${\alpha }_{400}^{815}$ (left) for D3 (green points). The bottom row shows ${\alpha }_{53}^{144}$ vs ${\alpha }_{144}^{400}$ for the southern large-scale region, including D1, the bridge, and the diffuse emission. For the plots shown in the middle and bottom row, images at 25 arcsec were used for the measurements. The boxes used (one-beam area), colour-coded according to the different regions, are shown in the left panels of each row. In all plots the dashed line represents the bisector line (where α_high = α_low), the other lines represent various ageing models as a reference.