Band 6 short (top) and long (bottom) baseline continuum maps at 259 GHz. Contour levels are drawn at [2, 4, 8, 16, 32, 64, 128, 256, 512, 1024]  ×  rms, where the background rms equals 0.022 mJy/beam in the B6SB map and 0.013 mJy/beam in the B6LB map. The synthesised beam sizes are drawn in the bottom left as filled ellipses, and the cyan cross indicates the AGN position (as defined in Sect. 3.4). The phoenix feature is indicated with a white arrow. The polar and equatorial directions mentioned throughout the text are shown in the upper panel.