Visual Telescope in Vatican

The Zeiss Visual Refractor was installed in 1935 on an equatorial mount under an 8.5 m rotating dome atop the Apostolic Palace. It was equipped  with a Graff photometer for observing variable stars and a micrometer for measuring double stars. Later a Danjon stellar interferometer was added. The telescope has a 40 cm objective lens with 6 m focal length.