Spectral index maps of MRC 2011-298 for different frequency pairs and resolution. The overlaid contour levels are [±5, 10, 20, 40, ...] × σ from the lower frequency image. From top left to bottom right: 170–367 MHz map at 18″, 170–700 MHz map at 18″, 367–700 MHz map at 12″, 367–1616 MHz map at 12″, 700–6063 MHz map at 6″, 1616–6063 MHz map at 9″, 700–2988 MHz map at 4″, and 6063–9000 MHz map at 3″. Corresponding error maps are shown in Fig. B.1.