Editing Mount Wilson Observatory (section)

== 60-inch telescope ==
[[File:60-inch Telescope.JPG|thumb|upright|The {{convert|60|in|m|adj=on}} telescope at Mt. Wilson]]

For the 60-inch telescope, [[George Ellery Hale]] received the {{convert|60|in|m|adj=on}} mirror blank, cast by [[Saint-Gobain]] in France, in 1896 as a gift from his father, William Hale. It was a glass disk {{convert|19|cm||abbr=on}} thick and weighing {{convert|860|kg||abbr=on}}. However it was not until 1904 that Hale received funding from the Carnegie Institution to build an observatory. Grinding began in 1905 and took two years. The mounting and structure for the telescope were built in [[San Francisco]] and barely survived the [[1906 San Francisco earthquake|1906 earthquake]]. Transporting the pieces to the top of Mount Wilson was an enormous task. [[First light (astronomy)|First light]] was December 8, 1908. It was, at the time, the largest operational telescope in the world.<ref name="lat"/> Lord Rosse's [[Leviathan of Parsonstown]], a 72-inch (1.8-meter) telescope built in 1845, was, by the 1890s, out of commission.

Although slightly smaller than the Leviathan, the 60-inch had many advantages including a far better site, a glass mirror instead of speculum metal, and a precision mount which could accurately track any direction in the sky, so the 60-inch was a major advance.
[[File:Voyage in Space page097.jpg|left|thumb|Five-foot telescope being transported up the mountain]]
[[File:PSM V74 D518 Steel building and 60 inch reflector.png|thumb|left|Steel dome of the 60-inch telescope in 1909]]

The 60-inch telescope is a reflector telescope built for [[Newtonian telescope|Newtonian]], [[Cassegrain reflector|Cassegrain]] and [[Coudé focus|coudé]] configurations. It is currently used in the bent Cassegrain configuration. It became one of the most productive and successful telescopes in astronomical history. Its design and light-gathering power allowed the pioneering of [[spectroscopic]] analysis, [[parallax]] measurements, [[nebula]] photography, and [[Photometry (astronomy)|photometric]] photography.<ref>{{Cite web |url=http://www.mtwilson.edu/Simmons3.html |title=Mount Wilson Observatory |access-date=2015-08-11 |archive-url=https://web.archive.org/web/20150905105144/http://www.mtwilson.edu/Simmons3.html |archive-date=2015-09-05 |url-status=dead }}</ref> Though surpassed in size by the {{section link||100-inch Hooker telescope}} nine years later, the 60-inch telescope remained one of the largest in use for decades.

In 1992, the 60-inch telescope was fitted with an early [[adaptive optics]] system, the ''Atmospheric Compensation Experiment'' (ACE). The 69-channel system improved the potential resolving power of the telescope from 0.5 to 1.0 arc sec to 0.07 arc sec. ACE was developed by [[DARPA]] for the [[Strategic Defense Initiative]] system, and the [[National Science Foundation]] funded the civilian conversion.

The telescope is used for public outreach as the second largest telescope in the world devoted to the general public. Custom made 10&nbsp;cm eyepieces are fitted to its focus using the bent cassegrain configuration to provide views of the Moon, planetary, and deep-sky objects. Groups may book the telescope for an evening of observing.<ref>{{cite web|title=Astronomical Observing through the Mount Wilson 60-inch Telescope |url=http://www.mtwilson.edu/60-inch/60inVisitorPackage.pdf |url-status=dead |archive-url=https://web.archive.org/web/20131228071438/http://www.mtwilson.edu/60-inch/60inVisitorPackage.pdf |archive-date=December 28, 2013 }}</ref>