Spectral age maps of the fitted regions in 4C 43.15 after fitting a JP+Tribble model to the LBA, HBA, and VLA data. From left to right: spectral age of the plasma, its positive uncertainty, and the χ² value of the regions. The maps are shown at a 0.9″ resolution. The grey contours are drawn based on the 4.71 GHz map, starting at 0.29 mJy beam⁻¹. Each contour represents a factor of increase in intensity.