Left to right: continuum images with insets showing a zoom in the cavity; CLEANed galario model images; CLEANed residual images; zoom on the northern (1) and southern (2) sides of the outer ring residuals. Contours start at 3σ and increase by 1σ. The green ellipses approximate the 7σ contours of the continuum data. The datasets are ordered from band 7 to band 6 and by epoch from top to bottom.