Array and the NRAO 12m radio telescope.
Molecular clouds are the sites where stars form in galaxies.
The spacing between the telescopes determines what size features the interferometer is sensitive to. The further apart the telescopes are, the smaller size the interferometer is sensitive too. Thus a full-synthesis image is never possible for a traditional radio interferometric observations. The single dish observations of this source are shown in the next figure. The contrast in the resolution between the two maps should be obvious.