Hale reflector

Hale telescope

Named after	George Ellery Hale
Observatory	Palomar Observatory
Location(s)	Palomar Mountain, California, US
Coordinates	33°21′23″N 116°51′54″W / 33.35631°N 116.86489°W / 33.35631; -116.86489Coordinates: 33°21′23″N 116°51′54″W / 33.35631°N 116.86489°W / 33.35631; -116.86489
Altitude	1,713 m (5,620 ft)
Built	1936–1948 (1936–1948)
First light	January 26, 1949, 10:06 pm PST
Telescope style	optical telescope reflecting telescope
Diameter	200 in (16 ft 8 in)
Collecting area	31,000 sq in (220 sq ft)
Focal length	16.76 m (55 ft 0 in)
Mounting	Equatorial mount
Website	www.astro.caltech.edu/palomar/about/telescopes/hale.html
Location of Hale Telescope
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The Hale Telescope is a 200-inch (5.1 m), f/3.3 reflecting telescope at the Palomar Observatory in California, US, named after astronomer George Ellery Hale. With funding from the Rockefeller Foundation, he orchestrated the planning, design, and construction of the observatory, but did not live to see its commissioning. The Hale was groundbreaking for its time, with double the diameter of the next largest telescope and pioneering the use of many technologies such as vapor deposited aluminum and low thermal expansion glass. It is still in active use.

It was the largest optical telescope in the world from its completion in 1948 until the BTA-6 was built in 1976, and the second largest until the construction of the Keck 1 in 1993.

Hale supervised the building of the telescopes at the Mount Wilson Observatory with grants from the Carnegie Institution of Washington: the 60-inch (1.5 m) telescope in 1908 and the 100-inch (2.5 m) telescope in 1917. These telescopes were very successful, leading to the rapid advance in understanding of the scale of the Universe through the 1920s, and demonstrating to visionaries like Hale the need for even larger collectors.

The chief optical designer for Hale's previous 100-inch telescope was George Willis Ritchey, who intended the new telescope to be of Ritchey–Chrétien design. Compared to the usual parabolic primary, this design would have provided sharper images over a larger usable field of view. However, Ritchey and Hale had a falling out. With the project already late and over budget, Hale refused to adopt the new design, with its complex curvatures, and Ritchey left the project. The Mount Palomar Hale telescope turned out to be the last world-leading telescope to have a parabolic primary mirror.