The Sheepshanks Equatorial Telescope was a 6.7-inch (170 mm) aperture refracting telescope installed in 1838 at the Royal Observatory in Greenwich.^[1] The telescope was donated to the observatory by the astronomer Richard Sheepshanks. The telescope had a doublet objective lens made by Cauchoix of Paris.^[2] Originally it was mounted on a clockwork driven equatorial mounting by the Grubb Telescope Company on a stone pillar.^[3][4]

From 1835 to 1963 it was mounted in Greenwich Observatory's Sheepshanks Dome (located between the later Great Equatorial Building and the Prime Meridian); from 1963 to 1982 it was mounted in the Altazimuth Pavilion.^[3] In the early 1980s it was placed in storage.^[3]

The focal length of the telescope has been quoted as 6 feet 2+1⁄2 inches (1.892 meters) in one source,^[3] but according to another it is 8 feet 2 inches (2.49 meters).^[5] The telescope tube was made of wood.^[6]

An 1840 report from the Observatory noted of the new Sheepshanks telescope:^[7]

The power and general goodness of this telescope make it a most welcome addition to the instruments of the observatory

Still in service over half a century later, an 1896 report by W. H. M. Christie had this to say about the Sheepshanks at that time:^[5]

Its definition is good: A small quantity of colour from the secondary spectrum, and a diffusion of light from brilliant objects, being the principal defects.

At one time the Sheepshanks refractor was the largest aperture telescope at Greenwich.^[8] One of the instruments for the telescope was a wire micrometer.^[5]

Observations

One of its observations was of Comet Encke.^[7] The Sheepshanks was used to observe the Moon occulting stars in 1905.^[9][10] Some of the stars that were observed include Bradley 687, 130 Tauri, and 26 Geminorum- among others.^[9]

In addition to the occultation of stars by the Moon, the Sheepshanks equatorial is also reported to have been used to observe the moons of Jupiter.^[11]

Disambiguation

There are other telescopes bearing the name Sheepshanks, for example the Sheepshanks telescope No 3; this was a telescope of 4.6 inches aperture and 5 feet of focal length, used with a spectroscope in the 1860s.^[12] There was also a Sheepshanks telescope at Cambridge, completed in 1898.^[13]