The Sloan Digital Sky Survey is the deepest large scale survey of the
sky currently available. SkyView dynamically queries the SDSS archive
(current release DR16) to retrieve data and resample it into the user
requested frame. All releases after DR9 are spectra only, so all imaging data
originates from DR9. Further information about SDSS and many additional services
are available at the <a href="https://www.sdss.org">SDSS website</a>. Provenance: Sloan Digital Sky Survey Team. This is a service of NASA HEASARC.