Dirty maps of a single point source simulated into the visibilities. The images on the left are made using the simulated visibilities directly. The images on the right are made using the superstation visibilities: at the top they are simulated directly, and at the bottom they result from post-processing beamforming. The higher spatial frequencies are suppressed: this accounts for the absence of the x-shaped artefact in panel d: this artefact is in fact the part of the PSF that corresponds to our high spatial frequencies. The peak flux values are: 1.77 Jy in panel a, 1.77 Jy in panel b, 1.74 Jy in panel c, and 1.09 Jy in panel d.