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The Zeiss 12 inch refracting telescope dome at the Griffith Observatory, Griffith Park, Los Angeles

From the Griffith Observatory website:

 

Since opening in 1935, more than seven million people have put an eye to Griffith Observatory's original 12-inch Zeiss refracting telescope. More people have looked though it than any other telescope in the world. Located in the roof-top dome on the building's east end, the Zeiss telescope is intended mainly for nighttime viewing by the general public, commonly targeting the Moon, planets, and brightest showpiece objects of our galaxy. A popular public destination when special celestial events occur, more people viewed Halley's Comet and comets Hale-Bopp and Hyakutake through the Observatory's Zeiss telescope than any other telescope on the planet.

 

The telescope itself is in excellent condition and was unchanged by the renovation and expansion project. The copper roof of the telescope dome was repaired and restored, and the dome's drive mechanisms were replaced. The most significant change is the addition of a new exhibit station located in the Hall of the Eye exhibit hall below the telescope dome. The station provides live video and audio feeds from the telescope and allows visitors unable to climb the stairs into the telescope dome to have an observing experience. Most nights, other telescopes also are available on either the roof or front lawn to allow those in wheelchairs to observe directly.

 

When the night sky is clear, the Zeiss telescope is open from the roof and serves up to 600 visitors per night. One of the Observatory's experienced telescope demonstrators guides the public in looking through the eyepiece of the 12-inch Zeiss refractor (so called because its light is collected and focused by a 12-inch diameter glass lens at the front of the 16-foot-long telescope tube). The main telescope tube carries a smaller 9 -inch refracting telescope piggyback, which permits two different views of a single object, as appropriate.

 

The telescope sits on a tilted mounting (an equatorial mount) aligned with the Earth's axis, and it is slowly turned by a motor to compensate for the Earth's rotation so that objects remain centered in view for as long as is desired. Counterweights precisely balance the telescope so that the Telescope Demonstrator can easily move the instrument by hand in spite of its 9,000-pound weight. The unique design of construction by Zeiss also counteracts the bending of the telescope due to gravity with counterweighted levers in the telescope's tube and mounting. Such a system is said to be "stress compensated."

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Uploaded on October 9, 2010
Taken on December 17, 2009