Dirty images of the real observed NCP dataset in the direction of Cyg A. The top row shows, from left to right: (i) the image after initial calibration, and residual images after DD subtraction using the (ii) new, (iii) old and (iv) point source model, divided by the peak brightness of the initially calibrated image. The bottom row shows the differences between residual images obtained after DD subtraction for the three Cyg A models: Old − New (left), Point − New (middle), and Point − Old (right). All the images have been obtained with a natural weighting scheme and using a baseline range of 50 − 4500λ, resulting in the synthesised beam shown in the bottom-left corner of the top-left panel. The contour in every panel is the 1 Jy/beam level from Fig. 1 to show the position and extension of Cyg A.