File:Great Refractor Potsdam.jpgDescriptionGreat Refractor Potsdam.jpg English: The Great Refractor of the Astrophysical Observatory Potsdam (AOP), Germany, was finished in 1899. It
File:Dome Great Refractor Potsdam.jpgDescriptionDome Great Refractor Potsdam.jpg English: Dome of the Great Refractor at the Astrophysical Observatory Potsdam (AOP), Germany. The diameter
File:Potsdam Great Refractor.jpgDescriptionPotsdam Great Refractor.jpg English: The "Great Refractor" of the Leibniz Institute for Astrophysics, Germany. This double refractor, completed