Above, we have addressed the issue of noise performance with respect to tapering the beam, which is pertinent for imaging weak sources. Another consideration in choosing a Fourier plane distribution for the MMA is the image dynamic range which can be achieved for very bright sources. Interferometric images of very bright sources are not limited by thermal noise, but by other systematic errors. VLA images of sources dominated by a single bright unresolved source are dynamic range limited at the level of a few 100,000:1 by unknown systematic effects. VLA images of more complicated sources dominated by extended emission are typically dynamic range limited at the level of 10,000:1, presumably due to deconvolution errors. It seems likely that we can design the MMA configurations to give high dynamic range deconvolution. The Fourier plane distribution of an array determines the character of the sidelobes in the point spread function, and a point spread function with small sidelobes encourages a high dynamic range deconvolution. Such reasoning would indicate that the uniform Fourier plane coverage would result in poorer images than the tapered coverage.
Simulations using the abstract Fourier plane coverages mentioned above without adding thermal noise have given conflicting results. I have simulated observations of our standard MMA source model, a planet model, and a random collection of point sources. The simulated data were naturally weighted, gridded, Fourier transformed, and deconvolved using both CLEAN and MEM. Uniform Fourier plane distribution results in images with dynamic range at full resolution which is 10-50% than images made from a centrally condensed Fourier plane distribution. As the visibilities are tapered, the uniform distribution images become comparable to the centrally condensed images after the resolution is degraded by 50-100%. However, Morita (private communication) has performed simulations using abstract uniform and moderately centrally condensed Fourier plane distributions which have been imaged using uniform weighting. Morita finds that the uniform Fourier plane coverage results in higher dynamic range images. These conflicting results are not necessarily in conflict since the uniform weighting will up-weight the sparsely sampled long baseline (u,v) points of the tapered Fourier distribution, possibly resulting in larger image reconstruction errors.