Radio spectral index distribution. The top row shows, from left to right, the non-thermal radio spectral index between 54 and 144 MHz (panel a), between 144 and 1365 MHz (panel b), and between 4850 and 8350 MHz (panel c). Contours are at −1.2, −0.85, and −0.65. The bottom row (panels d–f) shows the corresponding radio spectral index error. The angular resolution is 47 arcsec for the maps between 54 and 144 MHz, and 20 arcsec otherwise. The size of the synthesised beam is shown in the bottom left corner of each panel.