Spectral index profiles of the three radio galaxies made along the slices marked in Figs. 4, 5, and 6, and the complementary error maps. The dots mark the outer double measurements taken from the low-resolution maps, and the squares mark the inner double and core measurements taken from the high-resolution maps. Because the inner double of J1528+0544 is small, the spectral index presented in the middle panel is averaged over the volume of the lobes.