Can somebody explain why it is interesting to get a much-lower resolution image than the VLA provided? Is it sampling some property the VLA image does not? (E.g., 8+ GHz samples higher-energy processes.) Or is this an exercise in technique (one person doing the work of an institute?), or in extracting usable data from antennas not built for the purpose? Background and motivation would be helpful.
[Edit:] The previous paper is helpful: "Here we show a complete description of the interferometric pipeline, covering from the IQ output of the SDRs to the CLEAN images. Therefore, this experiment is a valuable resource for anyone interested in learning about interferometry in radio astronomy."
The ATA has less and shorter baselines, each made of much smaller collecting elements than the (E)VLA. Put simply, baselines bring resolution, collecting area brings sensitivity, and both are intricate (the longer the baseline, the more sensitivity you need).
Have a look also at VLBA techniques, which allow for even higher resolutions. Such a technique was used with the EHT to "image" the M87 blackhole.