Left: spectral index map in the range 144−614 MHz. Middle: spectral index map in the range 1400−4850 MHz. Right: spectral curvature map SPC = –. All three maps show a clear steepening moving from the inner regions of the lobes towards the edges of the lobes. The spatial resolution of all radio maps is 6 arcsec × 6 arcsec. The black rectangular regions in the middle panel have been used to study the spectral index variations throughout the lobes (see Fig. 6).