(a) The spectral index map from 144–1360 MHz and (b) 1360–4850 MHz for the large-scale lobes emission of 3C 293. All the maps are overlaid with contours of the 1360 MHz image at 10.5′′ × 7′′ resolution with the contour levels at (5, 30, 150, 350, 700) × σ_RMS where σ_RMS = 0.09 mJy beam⁻¹ is the local RMS noise. A flatter spectrum with < 0.5 can be seen in the centre of the 144–1360 MHz map. The 1360–4850 MHz spectral index map does not include most of the southern lobe, since very little emission from the southern lobe is recovered at 4850 MHz.