The Crossley telescope is a
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 ...
located at
Lick Observatory
The Lick Observatory is an astronomical observatory owned and operated by the University of California. It is on the summit of Mount Hamilton, in the Diablo Range just east of San Jose, California, United States. The observatory is managed by th ...
in the
U.S. state
In the United States, a state is a constituent political entity, of which there are 50. Bound together in a political union, each state holds governmental jurisdiction over a separate and defined geographic territory where it shares its sover ...
of
California
California is a U.S. state, state in the Western United States, located along the West Coast of the United States, Pacific Coast. With nearly 39.2million residents across a total area of approximately , it is the List of states and territori ...
. It was used between 1895 to 2010, and was donated to the observatory by
Edward Crossley
Edward Crossley (1841 – 21 January 1905) was an England, English businessman, Liberal Party (UK), Liberal Party politician and astronomer.
Biography
Edward Crossley was the eldest son of Joseph Crossley J.P., of Broomfield, Halifax, Yorkshire ...
, its namesake.
It was the largest glass reflecting telescope in the United States for several years after its recommissioning in California.
Lick Director,
James Edward Keeler
James Edward Keeler (September 10, 1857 – August 12, 1900) was an American astronomer. He was an early observer of galaxies using photography, as well as the first to show observationally that the rings of Saturn do not rotate as a solid body ...
, remarked of the Crossley in 1900, "... by far the most effective instrument in the Observatory for certain class of astronomical work."
History
Given to the Lick Observatory in 1895 by
British
British may refer to:
Peoples, culture, and language
* British people, nationals or natives of the United Kingdom, British Overseas Territories, and Crown Dependencies.
** Britishness, the British identity and common culture
* British English, ...
politician
Edward Crossley
Edward Crossley (1841 – 21 January 1905) was an England, English businessman, Liberal Party (UK), Liberal Party politician and astronomer.
Biography
Edward Crossley was the eldest son of Joseph Crossley J.P., of Broomfield, Halifax, Yorkshire ...
, it was rebuilt from the ground up as it was on a very flimsy mounting. It was last used in 2010 in the search for
extra-solar planets
An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...
but has been taken out of service due to budget cuts. The mirror, and some of the initial mounts, came from the
36-inch reflector originally mounted in
Andrew Ainslie Common
Andrew Ainslie Common Fellow of the Royal Society, FRS (1841–1903) was an English amateur astronomer best known for his pioneering work in astrophotography.
Biography
Common was born in Newcastle Upon Tyne on 7 August 1841. His father, Thomas ...
's backyard
Ealing
Ealing () is a district in West London, England, west of Charing Cross in the London Borough of Ealing. Ealing is the administrative centre of the borough and is identified as a major metropolitan centre in the London Plan.
Ealing was histor ...
observatory. He had used it from 1879 to 1886 to prove the concept of long exposure
astrophotography
Astrophotography, also known as astronomical imaging, is the photography or imaging of astronomical objects, celestial events, or areas of the night sky. The first photograph of an astronomical object (the Moon) was taken in 1840, but it was no ...
(recording objects too faint to be seen by the naked eye for the first time). Common sold it to Crossley who had it until 1895.
The 36-inch A.A.Common mirror was made by George Calver for Common, and was ordered after Common wanted one bigger than the 18-inch reflecting telescope, which also had a mirror from Calver. Common completed this telescope by 1879, and went on to make a 60-inch telescope; he sold the 36-inch to Crossley.
Crossley set the telescope up in
Halifax, England
Halifax () is a minster and market town in the Metropolitan Borough of Calderdale in West Yorkshire, England. It is the commercial, cultural and administrative centre of the borough, and the headquarters of Calderdale Council. In the 15th cen ...
in a new dome.
Meanwhile, at the Lick Observatory in California,
Edward S. Holden, the director, learned that Crossley wanted to sell the well-regarded Common 36-inch telescope.
Holden and Crossley exchanged letters and worked out transferring the telescope.
Crossley was very impressed by the enhanced observing conditions at
Mount Hamilton, and, in April 1895, he formally telegraphed the Lick that he would donate the telescope.
Funds had to be raised to ship the telescope to California, which included money from various donors including many small donations from members of the public, as well as donated services.
For example, the heavy parts of the telescope were shipped by
The Southern Pacific Company at no cost, a service of over $1,000 USD (at that time).
Converting the buying power of 1896 dollars to 2017 dollars, that can be estimated at approximately $12,000 USD.
The reflecting telescope type was scarcely used in the United States at the time of the donation, with a noted exception being the work of
H. Draper's reflector.
Observations by Keeler helped establish large reflecting telescopes with metal-coated glass mirrors as astronomically useful, as opposed to earlier cast
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 ...
mirrors.
Great refractors
Great refractor refers to a large telescope with a lens, usually the largest refractor at an observatory with an equatorial mount. The preeminence and success of this style in observational astronomy defines an era in modern telescopy in the 19t ...
were still in vogue, but the Crossley reflector foreshadowed the success of large reflectors in the 1900s. Other large reflectors followed, such as the ''Harvard 60-inch Reflector'' (152 cm), also with a mirror by A.A. Common, or the ''1 Meter Spiegelteleskop'' (39.4 inch reflector) of the
Hamburg Observatory
Hamburg Observatory (german: Hamburger Sternwarte) is an astronomical observatory located in the Bergedorf borough of the city of Hamburg in northern Germany. It is owned and operated by the University of Hamburg, Germany since 1968, although it ...
. At this time the 72-inch
Leviathan of Parsonstown
Leviathan of Parsonstown, or Rosse six-foot telescope, is a historic reflecting telescope of aperture, which was the largest telescope in the world from 1845 until the construction of the Hooker Telescope in California in 1917. The Rosse six-f ...
was the largest by aperture, but it used a metal mirror. Despite the accomplishments of reflectors under Herschel, in the 19th century much of the astronomical community used relatively small refractors, often just a few inches in aperture, save for a few larger ones.
After Keeler died unexpectedly in 1900,
William W. Campbell, now Lick Observatory's astronomer-in-charge, assigned Assistant Astronomer
Charles Dillon Perrine
Charles Dillon Perrine (July 28, 1867June 21, 1951) was an American astronomer at the Lick Observatory in California (1893-1909) who moved to Cordoba, Argentina to accept the position of Director of the Argentine National Observatory (1909-1936). ...
"to take charge of all duties in connection with the Crossley" including completing Keeler's observation of the near-Earth asteroid
433 Eros
Eros (minor planet designation: (433) Eros), provisional designation is a stony asteroid of the Amor group and the first discovered and second-largest near-Earth object with an elongated shape and a mean diameter of approximately . Visi ...
, for the determination of the
solar parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby objects ...
.
Perrine further significantly reconstructed the telescope from 1902 to 1905. Perrine would use the rebuilt Crossley to great effect in discovering eight comets and the sixth and seventh satellites (moons) of Jupiter. The Crossley was so effective that when Perrine became the director of the
Argentine National Observatory in Cordoba in 1909, he established a program to install a 60-inch (76-centimeter) reflecting telescope in Argentina. At that time it would have been equal to the largest reflector on Earth. After a world war and national economic crisis the "Perrine telescope" at the Bosque Alegre astrophysical station (
Estación Astrofísica de Bosque Alegre) was inaugurated in 1942 when it was the largest reflector in South America.
In the 1930s, the Crossley mirror was tested with vapor-deposited
aluminum
Aluminium (aluminum in American and Canadian English) is a chemical element with the symbol Al and atomic number 13. Aluminium has a density lower than those of other common metals, at approximately one third that of steel. It has ...
for reflection, rather than coated by using a
silver metal precipitated out of a solution. The telescope was aluminized in 1934, 1938, 1946, and 1951.
Nicholas Mayall
Nicholas Ulrich Mayall (May 9, 1906 – January 5, 1993) was an American observational astronomer. After obtaining his doctorate from the University of California, Berkeley, Mayall worked at the Lick Observatory, where he remained from 1934 to 1 ...
was a long time user of the Crossley and added a
slitless spectrograph to extend its usefulness in the face of larger telescopes.
Image:Crossley entrance.jpg
Image:Crossley cameraAtPrime.jpg
Discoveries & Observations
NGC 185
NGC 185 (also known as Caldwell 18) is a dwarf spheroidal galaxy located 2.08 million light-years from Earth, appearing in the constellation Cassiopeia. It is a member of the Local Group, and is a satellite of the Andromeda Galaxy (M31). NGC ...
was first photographed between 1898 and 1900 by
James Edward Keeler
James Edward Keeler (September 10, 1857 – August 12, 1900) was an American astronomer. He was an early observer of galaxies using photography, as well as the first to show observationally that the rings of Saturn do not rotate as a solid body ...
with the Crossley reflector.
Other early photographic imaging targets, dating to 1899, include GC 4628 and GC 4964, GC 4373, and the "
Ring nebula in Lyra."
Keeler notes that in a 4 hour exposure, 16 new nebulae were found, seeing objects that were normally much to hard to make out with the reflector visually.
1899: As an example of its performance, Keeler noted that in a two-hour exposure of the "cluster in Hercules" made on July 13, 1899, he could count 5400 stars on the photograph.
Keeler noted how with long exposure on this telescope the "swarms of minute stars" that gave it a nebulous look were resolved.
In 1900, Assistant Astronomer
Charles Dillon Perrine
Charles Dillon Perrine (July 28, 1867June 21, 1951) was an American astronomer at the Lick Observatory in California (1893-1909) who moved to Cordoba, Argentina to accept the position of Director of the Argentine National Observatory (1909-1936). ...
took hundreds of photographs of the near-Earth asteroid
433 Eros
Eros (minor planet designation: (433) Eros), provisional designation is a stony asteroid of the Amor group and the first discovered and second-largest near-Earth object with an elongated shape and a mean diameter of approximately . Visi ...
for the determination of the
solar parallax
Parallax is a displacement or difference in the apparent position of an object viewed along two different lines of sight and is measured by the angle or semi-angle of inclination between those two lines. Due to foreshortening, nearby objects ...
.
From 1902-05, after significant reconstruction by Perrine, he discovered eight comets and the sixth and seventh satellites (moons) of Jupiter.
1940:
Mayall's Object
Mayall's Object (also classified under the Atlas of Peculiar Galaxies as Arp 148) is the result of two colliding galaxies located 500 million light years away within the constellation of Ursa Major. It was discovered by American astronomer Nichol ...
was discovered by American astronomer
Nicholas U. Mayall of the
Lick Observatory
The Lick Observatory is an astronomical observatory owned and operated by the University of California. It is on the summit of Mount Hamilton, in the Diablo Range just east of San Jose, California, United States. The observatory is managed by th ...
on 13 March 1940, using the Crossley reflector.
In 1990, the Crossley was used to test the photometric detection of
exoplanets
An exoplanet or extrasolar planet is a planet outside the Solar System. The first possible evidence of an exoplanet was noted in 1917 but was not recognized as such. The first confirmation of detection occurred in 1992. A different planet, init ...
, including around the star
CM Draconis
CM Draconis (GJ 630.1A) is an eclipsing binary system approximately 47 light-years away in the constellation of Draco (the Dragon). The system consists of two nearly identical red dwarf stars located in the constellation Draco. The two ...
.
Comet
A comet is an icy, small Solar System body that, when passing close to the Sun, warms and begins to release gases, a process that is called outgassing. This produces a visible atmosphere or coma, and sometimes also a tail. These phenomena ar ...
s known to have been photographed using the Crossley include:
* 1931 I (1931d) was found on plates taken in January 1931.
* 1941 IV (1941c) was observed visually and photographed in July 1941, after the comet re-emerged from around the Sun.
* 1946 III (1946b) was observed visually in July 1946.
* 1946 IV (1946e) was recorded on plates taken in June and July 1946.
In 1978, the Crossley was used to observe
planetary nebulae
A planetary nebula (PN, plural PNe) is a type of emission nebula consisting of an expanding, glowing shell of ionized gas ejected from red giant stars late in their lives.
The term "planetary nebula" is a misnomer because they are unrelated ...
with photoelectric photometry (
spectrophotometry
Spectrophotometry is a branch of electromagnetic spectroscopy concerned with the quantitative measurement of the reflection or transmission properties of a material as a function of wavelength. Spectrophotometry uses photometers, known as spec ...
).
Contemporaries on debut
*
*
*
(100 cm equals 1 meter)
*Note the Leviathan of Parsonstown was not used after 1890
See also
*
List of largest optical telescopes in the 19th century
List of largest optical telescopes in the 19th century, are listings of what were, for the time period of the 19th century large optical telescopes. See List of largest optical telescopes in the 20th century for the 1900s. The list includes various ...
*
List of largest optical telescopes in the 20th century
The following is a list of the largest optical telescopes in the 20th century, paying special attention to the diameter of the mirror or lens of the telescope's objective, or aperture. Aperture rank currently goes approximately by the usable physi ...
*
List of largest optical reflecting telescopes
A ''list'' is any set of items in a row. List or lists may also refer to:
People
* List (surname)
Organizations
* List College, an undergraduate division of the Jewish Theological Seminary of America
* SC Germania List, German rugby union ...
References
External links
{{commons category, Crossley telescope
ucolick.org - Telescopes of the Lick Observatory - The 36 inch Crossley ReflectorPhotographs of the Crossley Telescope used in the Lick Observatory from the Lick Observatory Records Digital Archive, UC Santa Cruz Library’s Digital CollectionsTHE OPTICAL PERFORMANCE OF THE NEW ALUMINIZED MIRROR OF THE CROSSLEY TELESCOPE(year - 1934)
Optical telescopes
Lick Observatory