All MAST catalog holdings are available via a ConeSearch endpoint.
This service provides access to all, with an optional non-standard parameter for an individual catalog to query.
The available missions are listed at http://archive.stsci.edu/vo/mast_services.html,
and include Hubble (HST) data, Kepler, K2, IUE, HUT, EUVE, FUSE, UIT, WUPPE, BEFS, TUES, IMAPS, High Level Science Products (HLSP), Copernicus, HPOL, VLA First, XMM-OM, and SWIFT.
UV spectra in the 1,400 - 3,200 Å range, resolution ~ 140, V_max ~ 14,
~ 400 observations of ~ 200 targets, 2 NASA-funded shuttle missions (12/90 & 3/95).
Note spectropolarimetry data is also available.