Visibility analysis of the continuum at 203.4 GHz. a), c) Show the observed visibilities (filled circles) and model visibilities (grey area). The observed data are vector-averaged for the purpose of better visualization. Only the averaged structure in circular symmetry can be observed in the plot. Full model visibilities are plotted in order to show the non-circular symmetric structure of the source. b), d) Represent a graphical view of the visibility fits of VLA3 shown in a) and c), respectively. The red plus sign is the peak position of the emission. Blue ellipse and filled circle stand for the Gaussian component and the point source.