Physics

• PDS: Planetary System Data

            An archive and source of scientific data from NASA planetary missions, astronomical observations, and laboratory measurements.

• Physical Reference Data

  A series of online databases hosted by NIST containing physical constants, spectroscopy data, X-ray and gamma-ray data and more

• Digital Lunar Orbiter Photographic Atlas of the Moon

  The definitive reference manual to the global photographic coverage of the Moon, a reproduction of the 675 plates contained in NASA SP-206, written by Bowker and Hughes.

• Digital Sky Survey

  Sloan and Palomar Sky Surveys

• Arecibo Observatory (Puerto Rico)

  National Astronomy and Ionosphere Center, Cornell University

• Chandra X-Ray Observatory (Earth orbit)

  Chandra X-Ray Center, Smithsonian Astrophysical Observatory and the National Aeronautics and Space Adminstration

• European Southern Observatory (Chile)

• FUSE: Far Ultraviolet Spectroscopic Explorer

  Johns Hopkins University (and others) and the National Aeronautics and Space Adminstration. Archive is at http://archive.stsci.edu/fuse/

• GALEX (Galaxy Evolution Explorer) (Earth Orbit)

  California Institute of Technology and the National Aeronautics and Space Adminstration

• Greenwich (Royal Observatory) (Great Britain)

  National Maritime Museum

• Harvard College Observatory (Massachusetts)

  Harvard University

• Hubble Space Telescope (Earth orbit)

  Space Telescope Science Institute and the National Aeronautics and Space Adminstration

• W. M. Keck Observatory (Hawaii)

  California Association for Research in Astronomy

• Lowell Observatory (Arizona)

• Mount Wilson Observatory (California)

  Mount Wilson Institute

• National Astronomical Observatories, Chinese Academy of Sciences (China)

• National Astronomical Observatory of Japan (Japan)

• NOAO - National Solar Observatory (Arizona, New Mexico)

• l'Observatoire de Paris (France)

  French Ministry of Higher Education and Research

• Palomar Observatory (California)

  California Institute of Technology

• Pulkovo (Central Astronomical Observatory of the Russian Academy of Sciences) (Russia)

• South African Astronomical Observatory (South Africa)

• Spitzer Space Telescope (Earth orbit)

  Jet Propulsion Laboratory, California Institute of Technology and the National Aeronautics and Space Administration

• Yerkes Observatory (Wisconsin)

  Permanently Closed

• HyperPhysics - A free online resource covering many topics in astrophysics (and other branches of physics), maintained at Georgia State University.
• Weisstein's World of Astronomy - A free online resource covering many topics in astronomy, maintained by Wolfram Research.

Preprints/e-prints

• INSPIRE

  Database of particle physics papers maintained at Stanford Linear Accelerator Center (SLAC). Successor to SPIRES.

• CERN Document Server

  Particle physics articles, preprints, books and proceedings papers

• Mathematical Physics

  Preprint archive, 1991 to present