All MAST catalog holdings are available via a ConeSearch endpoint.
The Very Large Array (VLA) FIRST -- Faint Images of the Radio Sky at Twenty-cm -- is a project designed to produce the radio equivalent of the Palomar Observatory Sky Survey over 10,000 square degrees of the North and South Galactic Caps. Using the NRAO Very Large Array (VLA) and an automated mapping pipeline, we produce images with 1.8" pixels, a typical rms of 0.15 mJy, and a resolution of 5". At the 1 mJy source detection threshold, there are ~90 sources per square degree, ~35% of which have resolved structure on scales from 2-30". 30% of the sources have counterparts in the Sloan Digital Sky Survey.
The VLA FIRST catalog at MAST was published December 17, 2014. More information is available at http://sundog.stsci.edu
All available missions are listed at http://archive.stsci.edu/vo/mast_services.html.