Rosse Six Foot Telescope
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Leviathan of Parsonstown, or Rosse six-foot telescope, is a historic
reflecting telescope A reflecting telescope (also called a reflector) is a telescope that uses a single or a combination of curved mirrors that reflect light and form an image. The reflecting telescope was invented in the 17th century by Isaac Newton as an alternati ...
of
aperture In optics, the aperture of an optical system (including a system consisting of a single lens) is the hole or opening that primarily limits light propagated through the system. More specifically, the entrance pupil as the front side image o ...
, which was the largest telescope in the world from 1845 until the construction of the
Hooker Telescope The Mount Wilson Observatory (MWO) is an astronomical observatory in Los Angeles County, California, United States. The MWO is located on Mount Wilson, a peak in the San Gabriel Mountains near Pasadena, northeast of Los Angeles. The observ ...
in California in 1917. The Rosse six-foot telescope was built by
William Parsons, 3rd Earl of Rosse William Parsons, 3rd Earl of Rosse (17 June 1800 – 31 October 1867), was an English engineer and astronomer. He built several giant telescopes. His 72-inch telescope, built in 1845 and colloquially known as the "Leviathan of Parsonstown", was ...
on his estate,
Birr Castle Birr Castle ( Irish: ) is a large castle in the town of Birr in County Offaly, Ireland. It is the home of the 7th Earl of Rosse and his family, and as the castle is generally not open to the public, though the grounds and gardens of the deme ...
, at Parsonstown (now Birr) in Ireland.


Design and construction

Parsons improved the techniques of casting, grinding and polishing large telescope mirrors from
speculum metal Speculum metal is a mixture of around two-thirds copper and one-third tin, making a white brittle alloy that can be polished to make a highly reflective surface. It was used historically to make different kinds of mirrors from personal grooming a ...
, and constructed steam-powered grinding machines for parabolic mirrors. His mirror of 1839 was cast in smaller pieces and then fitted together before grinding and polishing; its 1840 successor was cast in a single piece. In 1842, Parsons cast his first mirror, but it took another five casts before he had two ground and polished mirrors. Speculum mirrors tarnished rapidly; with two mirrors, one could be used in the telescope while the other was being re-polished. The telescope tube and supporting structure were completed in 1845. The mirror was 5 inches (13 cm) thick and weighed almost 3 tons. This required a mirror cell to support and to prevent the mirror deforming under its own weight. The length of the tube and mirror box is about ; including the mirror it weighed about 12 tons. The tube is supported at the mirror end by a "universal joint", a hinge with two axes, which allows the tube to be inclined through a large range of
altitude Altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum (geodesy), datum and a point or object. The exact definition and reference datum varies according to the context (e.g., aviation, geometr ...
and also to be turned through a limited range of
azimuth An azimuth (; from ) is the horizontal angle from a cardinal direction, most commonly north, in a local or observer-centric spherical coordinate system. Mathematically, the relative position vector from an observer ( origin) to a point ...
. The azimuth range is limited to about one hour by the supporting walls that flank the tube on its eastern and western sides. The walls are apart, high, and long. A chain and counterweight keeps the telescope in balance, another chain with a winch controls the altitude. A
rack and pinion rack and pinion is a type of linear actuator that comprises a circular gear (the '' pinion'') engaging a linear gear (the ''rack''). Together, they convert between rotational motion and linear motion: rotating the pinion causes the rack to be d ...
beam underneath the tube controls the azimuth. This beam is connected to the eastern supporting wall, where it can move on a circular iron arc to allow the telescope to change altitude. The tube is of the Newtonian design with the
eyepiece An eyepiece, or ocular lens, is a type of lens that is attached to a variety of optical devices such as Optical telescope, telescopes and microscopes. It is named because it is usually the lens that is closest to the eye when someone looks thro ...
on its western side. At low altitude, the observer accesses the eyepiece from a wooden gallery that spans the distance between the walls and can slide up and down guides to follow the telescope in altitude. A cage on the gallery moves sideways to reach the eyepiece at different azimuth. At high elevation, curved galleries on top of the western wall are used, which can be moved across the wall to follow the telescope in azimuth.


Operation

The purpose of the telescope was to re-visit the nebulae in the catalogues of
Charles Messier Charles Messier (; 26 June 1730 – 12 April 1817) was a French astronomer. He published an astronomical catalogue consisting of 110 nebulae and star clusters, which came to be known as the ''Messier objects'', referred to with th ...
and
John Herschel Sir John Frederick William Herschel, 1st Baronet (; 7 March 1792 – 11 May 1871) was an English polymath active as a mathematician, astronomer, chemist, inventor and experimental photographer who invented the blueprint and did botanical work. ...
. These catalogues list star clusters as well as nebulae, and the question was whether the latter were merely unresolved star clusters or genuinely nebulous regions of space. It resolved into stars unclear areas which might be the first
galaxies A galaxy is a system of stars, stellar remnants, interstellar gas, dust, and dark matter bound together by gravity. The word is derived from the Greek ' (), literally 'milky', a reference to the Milky Way galaxy that contains the Solar Sys ...
to be identified as such. Parsons discovered that several nebulae had a spiral structure, suggesting "dynamical laws". The most notable spiral nebula observed by Parsons was
Messier 51 Messier may refer to: People with the surname *Ashley Messier (born 2002), Canadian ice hockey player *Charles Messier (1730–1817), French astronomer * Doug Messier (born 1936), Canadian ice hockey player and coach * Éric Messier (born 1973), Ca ...
, which he resolved into stars.''Observing and Cataloguing Nebulae and Star Clusters: From Herschel to Dreyer's New General Catalogue''
by Wolfgang Steinicke, year 2010, 650 pages. The book discusses Parsons' Leviathan telescope in section 6.4 (including page 115).
After William Parsons (the 3rd Earl of Rosse) died in 1867, the 4th Earl ( Laurence Parsons) continued to operate the six-foot telescope. From 1874 to 1878, J. L. E. Dreyer worked with the telescope and began the compilation of his '' New General Catalogue of Nebulae and Clusters of Stars''. Although the 4th Earl built a smaller 3 ft equatorial in 1876, the six-foot telescope remained in use until about 1890. After his death in 1908, the telescope was partly dismantled, and in 1914, one of the mirrors with its mirror box was transferred to the
Science Museum A science museum is a museum devoted primarily to science. Older science museums tended to concentrate on static displays of objects related to natural history, paleontology, geology, Industry (manufacturing), industry and Outline of industrial ...
in London. The walls remained. The tube, second mirror box, and universal joint survived.


Restoration

Following a TV programme, lecture, and book by
Patrick Moore Sir Patrick Alfred Caldwell-Moore (; 4 March 1923 – 9 December 2012) was an English amateur astronomer who attained prominence in that field as a writer, researcher, radio commentator and television presenter. Moore's early interest in astro ...
, there was renewed interest in the six-foot telescope in the 1970s. Gradually, the telescope became a visitor attraction. But it was not until the 1990s that plans to actually rebuild the telescope came to fruition. In 1994 the retired
structural engineer Structural engineers analyze, design, plan, and research List of structural elements, structural components and structural systems to achieve design goals and ensure the safety and comfort of users or occupants. Their work takes account mainly of ...
and
amateur astronomer Amateur astronomy is a hobby where participants enjoy observing or imaging celestial objects in the sky using the unaided eye, binoculars, or telescopes. Even though scientific research may not be their primary goal, some amateur astronomers m ...
Michael Tubridy Michael "Mick" Tubridy (born 6 August 1935 at Kilrush, County Clare, Ireland) is an Irish musician, step dancer and structural engineer. Career In November 1962, he was a founder member of the traditional Irish music group, The Chieftains, ...
was called in to research and re-design the Rosse six-foot telescope. The original plans were lost, and so it took detective work to review the remains of the telescope, incidental comments in observing logs, and contemporary photographs taken by
Mary Rosse Mary Parsons, Countess of Rosse (; 14 April 1813 – 1885), was an Anglo-Irish amateur astronomer, architect, furniture designer, and pioneering photographer. Often known simply as Mary Rosse, she was one of the early practitioners of making ph ...
, wife of the 3rd Earl. Reconstruction work lasted from early 1996 to early 1997. It had been planned to include a working mirror, but due to budget constraints this had to be left for a separate project. The new mirror was installed in 1999. Unlike the
speculum The term speculum, Latin for "mirror", and its plural specula, may refer to: * ''Speculum'' (journal), a journal of medieval studies published by the Medieval Academy of America * Speculum (medical), a medical tool used for examining body cavities ...
original, and unlike modern aluminium- or silver-coated glass mirrors, this is made of aluminium, as a compromise between authenticity and utility in astronomical observation.Telescope Restoration
". Birr Castle. Retrieved 22 November 2009.


LOFAR station

In 2017,
LOFAR LOFAR may refer to: * Low-Frequency Array, a large radio telescope system based in the Netherlands * Low Frequency Analyzer and Recorder and Low Frequency Analysis and Recording, for low-frequency sounds {{disambiguation ...
radio-telescope station IE613, one of some 50 similar stations in Europe, was constructed in the grounds of the castle. This is the westernmost station in the LOFAR network, which stretches as far east as Latvia. LOFAR makes observations in the 10 MHz to 240 MHz frequency range with two types of antennas: Low Band Antenna (LBA) and High Band Antenna (HBA), optimized for 10–80 MHz and 120–240 MHz respectively. The Birr Castle station consists of 96 LBAs and 96 HBAs and a total of 96 digital Receiver Units (RCUs). The Birr Castle station on its own is the Irish Low Frequency Array telescope. In 2018, observed for the first time a billion-year-old red-dwarf,
flare star A flare star is a variable star that can undergo unpredictable dramatic increases in brightness for a few minutes. It is believed that the flares on flare stars are analogous to solar flares in that they are due to magnetic reconnection, the magne ...
, namely CN Leo (
Wolf 359 Wolf 359 is a red dwarf star located in the constellation Leo, near the ecliptic. At a distance of from Earth, it has an apparent magnitude of 13.54 and can only be seen with a large telescope. Wolf 359 is one of the nearest stars to ...
), 7.9 light years away.Birr radio telescope catches flaring red dwarf 75 trillion kilometres away
Irish Times, 2018-03-27.


Pictures


See also

* List of largest optical telescopes historically *
Craig telescope The Craig telescope was a large telescope built in the 1850s, and while much larger than previous refracting telescopes, it had some problems that hampered its use. Its unique design and potential caused a great deal of excitement in its day. T ...
(refracting telescope of the 1850s) *
List of largest optical telescopes in the British Isles List of largest optical telescopes in Ireland and the United Kingdom is a list of the largest optical telescopes in the British Isles, including in the United Kingdom and Ireland. The most famous telescopes include Herschel's reflector, w ...
* List of largest optical telescopes of the 19th century *
Lists of telescopes This is a list of lists of telescopes. *List of astronomical interferometers at visible and infrared wavelengths *List of astronomical observatories *List of highest astronomical observatories *List of large optical telescopes *List of largest i ...


References


Further reading

* Patrick Moore (1981). ''The Astronomy of Birr Castle''. The Tribune Printing and Publishing Group, Birr. * Patrick Moore (1997). "The Leviathan Reborn". ''Sky & Telescope'', 94.5, p. 52. * D.H. Levy (2004). "Miracle at Birr Castle". ''Sky & Telescope'', 107.1, p. 84. * Wolfgang Steinicke.
William Parsons, 3rd Earl of Rosse
. Retrieved 22 November 2009. * WGBH NOVA/Time-Life Video
Beyond the Milky Way
. Interviews the 7th Earl of Rosse, gives the history of the Leviathan and how it worked, starting at 1:50 * The Monster Telescopes Erected by the Earl of Rosse. by Thomas Woods. Published 1844 London. Gives details of casting, polishing, and use of the large telescopes. Several editions are available at the Internet Archive. {{Portal bar, Ireland, Astronomy, Stars, Spaceflight, Outer space, Solar System, Education, Science Astronomical observatories in the Republic of Ireland Buildings and structures in Birr, County Offaly Reflecting telescopes