GTC Hα image of J1000+12, with overlaid contours of the VLA A (red) and B-configuration (grey) data. Contour levels are the same as in Fig. A.12. The inset shows the contours of the VLA A-configuration data overlaid onto the HST WFC3/FQ508N narrow-band filter that contains [OIII] emission. The dashed black rectangle marks the approximate location of the giant [OIII] bubble proposed by Jarvis et al. (2019). The narrow extension of radio emission at this location, which we coloured light-red in the small panel, is most likely dominated by artefacts of the snap-shot imaging. LR:A to LR:D indicate the main radio components with the same nomenclature as in Jarvis et al. (2019). Radio and Hα axes as in Fig. 2.