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Difference between revisions 1826690 and 1901176 on enwikiversity[[Image:Brorfelde Schmidt Telescope.jpg|thumb|right|2050px|The Schmidt Telescope at the former Brorfelde Observatory is now used by amateur astronomers. Credit: [[commons:User:Moeng|Mogens Engelund]].]] A '''radiation telescope''' is an instrument designed to collect and focus radiation so as to make distant sources appear nearer. {{clear}} ==Astronomy== {{main|Astronomy/Keynote lecture}} [[Image:Mauna Kea observatory.jpg|thumb|right|2050px|Sunset over four telescopes of the [[w:Mauna Kea Observatories|Mauna Kea Observatories]] is pictured, from left to right: the [[w:Subaru Telescope|Subaru Telescope]], the twin [[w:W. M. Keck Observatory|Keck I and II telescope]]s, and the [[w:NASA Infrared Telescope Facility|NASA Infrared Telescope Facility]]. Credit: [http://flickr.com/photos/35188692@N00 Alan L].]] [[Astronomy/Keynote lecture|Astronomy]] may be accomplished by observation using personal senses, or augmented with the use of instruments. The telescope itself can be moved on or by vehicles along the ground, on water, in the air, or above the Earth's atmosphere, and throughout the nearby [[Interplanetary medium/Keynote lecture|interplanetary medium]]. Observational astronomy benefits from electronics, mechanisms, tools, and machinery. "With its high altitude, dry environment, and stable airflow, Mauna Kea's summit is one of the best sites in the world for astronomical observation [at left], and one of the most controversial. Since the creation of an access road in 1964, thirteen telescopes funded by eleven countries have been constructed at the summit. The [[w:Mauna Kea Observatories|Mauna Kea Observatories]] are used for scientific research across the [[w:electromagnetic spectrum|electromagnetic spectrum]] from [[Visual astronomy|visible]] light to radio, and comprise one of the world's largest facilities of their type. Their construction on a "sacred landscape",<ref name="uh-2009">{{ cite book |title=Mauna Kea Comprehensive Management Plan: UH Management Areas |url=http://hawaii.gov/dlnr/occl/mauna-kea-management-plan/comprehensive-management-plan |format=PDF⏎ |last=Institute for Astronomy – University of Hawaii |publisher=Hawai`i State Department of Land and Natural Resources |accessdate=August 19, 2010 |date=January 2009 }}</ref> replete with endangered species and ongoing cultural practices, continues to be a topic of debate and protest. Studies are underway to determine their effect on the summit ecology, particularly on the rare [[w:Wēkiu bug|Wēkiu bug]]. It was designated a [[w:National Natural Landmark|National Natural Landmark]] in 1972.<ref name=nnl>{{ cite book |title=National Natural Landmark |url=http://www.nature.nps.gov/nnl/site.cfm?Site=MAKE-HI |publisher=National Park Service |accessdate=12 December 2012 }}</ref> There are nine telescopes working in the visible and infrared spectrum, three in the submillimeter spectrum, and one in the radio spectrum, with mirrors or dishes ranging from {{convert|0.9|m|ft|1|abbr=on}} to {{convert|25|m|ft|0|abbr=on}}.<ref name="telescope-table">{{ cite book |title=Mauna Kea Telescopes |url=http://www.ifa.hawaii.edu/mko/telescope_table.shtml |publisher=Institute for Astronomy – University of Hawaii |accessdate=August 29, 2010 }}</ref> {{clear}} ==Radiation== {{main|Radiation/Keynote lecture}} In physics, radiation is a process in which energetic particles or energetic waves travel through a medium or space. '''Def.''' an action or process of throwing or sending out a traveling ray in a line, beam, or stream of small cross section is called '''radiation'''. '''Def.''' the "shooting forth of anything from a point or surface, like the diverging rays of light; as, the radiation of heat"<ref name=RadiationWikt>{{ cite book |author=[[wikt:User:Długosz|Długosz]] |title=radiation |publisher=Wikimedia Foundation, Inc |location=San Francisco, California |monthdate=4 May⏎ |year= 2004 |url=http://en.wiktionary.org/wiki/radiation |accessdate=2015-03-28 }}</ref> is called '''radiation'''. Radiation that a particular telescope or a telescope array observes consists of fast moving entities from which information is gathered using spectroscopy, spatial distributions, or temporal distributions. A galaxy cluster that is moving is radiation and an astronomical object to be observed. Entities moving faster than the galaxy such as protons or photons are observables. ==Astrodesy== {{main|Astronomy/Observatories/Astrodesy|Astrodesy}} On [[Earth]], telescopes are positioned using [[geodesy]], such fields as surveying, structural geology of the underlying ground, and architecture. The availability of manpower is usually missing for extraterrestrial observatories on the [[Moon]], [[/Keynote lecture|Moon]], [[Mars/Keynote lecture|Mars]], or [[Venus]]. On the [[International Space Station]], manpower is often available for instrument control and use. ==Instruments== {{main|Instruments}} [[Image:MENISCAS 180.jpg|thumb|right|2050px|This is an optical telescope that may be used for optical and visual astronomy. Credit: .]] '''Def.''' any instrument used in astronomy for observing distant objects is called a '''telescope'''. '''Def.''' any instrument used in [[Astronomy/Keynote lecture|astronomy]] for observing distant objects (such as a radio telescope) is called a '''telescope''', or an '''astronomical telescope'''. {{clear}} ==Aerial telescopes== {{main|Radiation astronomy/Telescopes/Aerial|Aerial Telescopes}} [[Image:Aerialtelescope.jpg|thumb|right|2050px|An engraving of Huygens 210-foot aerial telescope showing the eyepiece and objective mounts and connecting string. Credit: .]] An '''aerial telescope''' is a type of very-long-focal-length [[w:refracting telescope|refracting telescope]] built in the second half of the 17th century that did not use a tube.<ref name=Rice>{{ cite book |title=The Telescope |url=http://galileo.rice.edu/sci/instruments/telescope.html |publisher=The Galileo Project |accessdate=5 March 2012 }}</ref> Instead, the [[w:Objective (optics)|objective]] was mounted on a pole, tree, tower, building or other structure on a swivel ball-joint. The observer stood on the ground and held the [[w:eyepiece|eyepiece]], which was connected to the objective by a string or connecting rod. By holding the string tight and maneuvering the eyepiece, the observer could aim the telescope at objects in the sky. “After about 1675, therefore, astronomers did away with the telescope tube. The objective was mounted on a building or pole by means of a ball-joint and aimed by means of a string...”<ref name=Rice/> {{clear}} ==Early telescopes== {{main|Early telescopes}} [[Image:Nimrud lens British Museum.jpg|thumb|right|250px|This image is a photo of the [[w:Nimrud lens|Nimrud lens]] in the [[w:British museum|British museum]]. Credit: [[commons:User:Geni|Geni]].]] "There are indeed ancient tablets that mention astronomers' lenses supported by a golden tube to enlarge the pupil, and in Nineveh a rock crystal [[w:Nimrud lens|lens]] was found (Pettinato 1998). Maybe one day a new archaeological excavation will find a Babylonian telescope for the first time."<ref name=Magli>{{ cite book |author=Giulio Magli |title=When the method is lacking, In: ''Mysteries and Discoveries of Archaeoastronomy from Giza to Easter Island'' |publisher=Copernicus Books |location=Rome, Italy |month= |yeardate=2009 |editor= |pages=97-116 |url=http://www.springerlink.com/content/w2q6g0q252221k0u/fulltext.pdf |bibcode= |doi=10.1007/978-0-387-76566-2_5 |pmid= |isbn=978-0-387-76564-8 |pdf=http://www.springerlink.com/content/w2q6g0q252221k0u/fulltext.pdf⏎ |accessdate=2011-10-15 }}</ref> {{clear}} ==Optics== {{main|Physics/Optics|Optics}} '''Optics''' involves the behavior and properties of [[w:light|light]], including its interactions with [[w:matter|matter]] and the construction of [[w:optical instruments|instruments]] that use or [[w:Photodetector|detect]] it.<ref name=McGrawHill>{{ cite book |title=McGraw-Hill Encyclopedia of Science and Technology |edition=5th |publisher=McGraw-Hill |yeardate=1993 }}</ref> Optics usually describes the behavior of [[w:visible light|visible]], [[w:ultraviolet|ultraviolet]], and [[w:infrared|infrared]] light. Because light is an [[w:electromagnetic wave|electromagnetic wave]], other forms of [[w:electromagnetic radiation|electromagnetic radiation]] such as [[w:X-ray|X-ray]]s, [[w:microwave|microwave]]s, and [[w:radio wave|radio wave]]s exhibit similar properties.<ref name=McGrawHill /> ==Colors== {{main|Radiation astronomy/Colors|Color astronomy|Colors}} "[B]roadband optical photometry of Centaurs and Kuiper Belt objects from the Keck 10 m, the University of Hawaii 2.2 m, and the Cerro Tololo InterAmerican (CTIO) 1.5 m telescopes [shows] a wide dispersion in the optical colors of the objects, indicating nonuniform surface properties. The color dispersion [may] be understood in the context of the expected steady reddening due to bombardment by the ubiquitous flux of cosmic rays."<ref name=Luu>{{ cite journal |author=Jane Luu and David Jewitt |title=Color Diversity among the Centaurs and Kuiper Belt Objects |journal=The Astronomical Journal |month=November |year=1996 |volume=112 |issue=5 |pages=2310-8 |url=http://adsabs.harvard.edu/full/1996AJ....112.2310L |arxiv= |bibcode=1996AJ....112.2310L |doi= |pmid= |accessdate=2013-11-05 }}</ref> ==Minerals== {{main|Minerals}} [[Image:Transparency.jpg|thumb|right|2050px|This shows a colorless and very clean quartz that is transparent. Credit: [[commons:User:Zimbres|Zimbres]].]] '''Quartz''' is the second-most-abundant [[w:mineral|mineral]] in the [[Earth]]'s [[w:continental crust|continental crust]], after [[w:feldspar|feldspar]]. Pure quartz, traditionally called ''rock crystal'' (sometimes called ''clear quartz''), is colorless and [[w:transparent materials|transparent]] or [[w:translucent|tra(contracted; show full) '''Def.''' the manufacture and use of radio telescopes is called '''radiotelescopy'''. ==Sources== {{main|Astronomy/Sources|Sources}} [[Image:Horizontal cyclotron with glowing beam.jpg|thumb|center|300px|This image shows a beam of accelerated ions (perhaps protons or deuterons) escaping the accelerator and ionizing the surrounding air causing a blue glow. Credit: Lawrence Berkely National Laboratory.]] [[Image:Synchrotron light.jpeg|thumb|right|2 050px|The image shows the blue glow given off by the synchrotron beam from the National Synchrotron Light Source. Credit: NSLS, Brookhaven National Laboratory.]] The image above shows a blue glow in the surrounding air from emitted cyclotron particulate radiation. At right is an image that shows the blue glow resulting from a beam of relativistic electrons as they slow down. This deceleration produces synchrotron light out of the beam line of the National Synchrotron Light Source. {{clear}} ==Bands== {{main|Radiation astronomy/Bands|Band astronomy}} [[Image:Rosetta.jpg|thumb|right|2050px|This is a 3D model of the Rosetta Spacecraft. The individual scientific payloads are highlighted in different colours. Credit: [[w:User:IanShazell|IanShazell]].]] For elongated dust particles in cometary comas an investigation is performed at 535.0 nm (green) and 627.4 nm (red) peak transmission wavelengths of the [[w:Rosetta (spacecraft)|Rosetta spacecraft]]'s OSIRIS Wide Angle Camera broadband green and red filters, respectively.<ref name=Bertini>{{ cite journal |author=I. Bertini, N. Thomas, and C. Barbieri |title=Modeling of the light scattering properties of cometary dust using fractal aggregates |journal=Astronomy & Astrophysics |month=January |year=2007 |volume=461 |issue=1 |pages=351-64 |url=http://www.aanda.org/articles/aa/full/2007/01/aa5461-06/aa5461-06.html |arxiv= |bibcode=2007A&A...461..351B |doi=10.1051/0004-6361:20065461 |pmid= |pdf=http://www.aanda.org/articles/aa/pdf/2007/01/aa5461-06.pdf |accessdate=2011-12-08 }}</ref> {{clear}} ==Backgrounds== {{main|Astronomy/Backgrounds|Background astronomy}} [[Image:Red-blue-noise.gif|frame|250px|The frame demonstrates an example of visual snow-like noise. Credit: .]] In astronomical [[w:Charge-coupled device|CCD]] technology, '''background''' is usually referred to the overall optical "noise" of the system, that is, the incoming light on the CCD sensor in absence of light sources. This background can originate from electronic noise in the CCD, from not-well-masked lights nearby the telescope, and so on. An exposure on an empty patch of the sky is also called a background, and is the sum of the system background level plus the sky's one. A '''background frame''' is often the first exposure in an astronomical observation with a CCD: the frame will then be subtracted from the actual observation result, leaving in theory only the incoming light from the astronomical object being observed. {{clear}} ==Meteor telescopes== {{main|Instruments/Telescopes/Meteors|Meteor telescopes}} [[Image:250mm Rain Gauge.jpg|thumb|upright|right|125px|The image shows a standard rain gauge. Credit: .]] Meteor telescopes per se are often other types of telescopes, such as optical telescopes, that happen or are slewed to observe meteors. At left is a collection device for rain on [[Earth]] as part of [[meteorology]]. There are favorable locations on Earth, Moon and Mars where [[meteorites]] are discovered. These meteorite, or micrometeorite, locations include Antarctica and the equatorial deserts. {{clear}} ==Cosmic-ray telescopes== {{main|Instruments/Telescopes/Cosmic rays|Cosmic-ray telescopes}} [[Image:HEAO-3.gif|thumb|right|2050px|This is an image of HEAO 3. Credit: .]] [[Image:Pioneer 10-11 - P52a - fx.jpg|thumb|left|1250px|The charged particle instrument (CPI) is used to detect cosmic rays in the solar system. Credit: NASA.]] [[Image:Pioneer 10-11 - P52b - fx.jpg|thumb|left|1250px|The cosmic-ray telescope collects data on the composition of the cosmic ray particles and their energy ranges. Credit: NASA.]] The [HEAO 3, at right, French-Danish] C-2 experiment measured the relative composition of the isotopes of the primary cosmic rays between beryllium and iron (Z from 4 to 26) and the elemental abundances up to tin (Z=50). Cerenkov counters and [[w:hodoscope|hodoscope]]s, together with the Earth's magnetic field, formed a spectrometer. They determined charge and mass of cosmic rays to a precision of 10% for the most abundant elements over the momentum range from 2 to 25 GeV/c (c=speed of light). "Recent measurements using the Goddard-University of New Hampshire cosmic-ray telescope [at left] on the ''Pioneer 10'' spacecraft have revealed an anomalous spectrum of nitrogen and oxygen nuclei relative to other nuclei such as He and C, in the energy range 3-30 MeV per nucleon."<ref name=McDonald>{{ cite journal |author=F. B. McDonald, B. J. Teegarden, and J. H. Trainor and W. R. Webber |title=The anomalous abundance of cosmic-ray nitrogen and oxygen nuclei at low energies |journal=The Astrophysical Journal |month=February 1. |year=1974 |volume=187 |issue=02 |pages=L105-8 |url=http://adsabs.harvard.edu/full/1974ApJ...187L.105M |arxiv= |bibcode=1974ApJ...187L.105M |doi=10.1086/181407 |pmid= |accessdate=2012-12-05 }}</ref> {{clear}} ==Neutron telescopes== {{main|Instruments/Telescopes/Neutrons|Neutron telescopes}} [[Image:Comptel.png|thumb|left|2050px|The Imaging Compton Telescope (COMPTEL) utilizes the Compton Effect and two layers of gamma-ray detectors. Credit: NASA.]] "In addition to observing gamma rays from a solar flare, [ the Imaging Compton Telescope] COMPTEL is also capable of detecting solar neutrons. Neutron interactions within the instrument occur when an incident solar neutron elastically scatters off a hydrogen nucleus in the liquid scintillator of an upper D1 module. The scattered neutron may then interact and deposit all or a portion of its energy in one of the lower D2 modules, providing the internal trigger signal necessary for a double scatter event. The energy of the scattered neutron is deduced from its time of flight from the upper to lower detector, which is summed with the energy measured for the recoil proton in the upper D1 module to obtain the energy of the incident solar neutron. The computed scatter angle of the neutron, as with gamma rays, yields an event circle on the sky, which can be further constrained since the true source of the detected neutrons is assumed to be the Sun."<ref name=Johnson>{{ cite book |author=W. N. Johnson |title=Appendix G to the NASA RESEARCH ANNOUNCEMENT for the COMPTON GAMMA RAY OBSERVATORY GUEST INVESTIGATOR PROGRAM |publisher=National Aeronautics and Space Administration Goddard Space Flight Center |location=Greenbelt, Maryland USA |monthdate=November⏎ |year= 1996 |url=http://heasarc.gsfc.nasa.gov/docs/cgro/nra/appendix_g.html#III.%20COMPTEL%20GUEST%20INVESTIGATOR%20PROGRAM |accessdate=2013-04-05 }}</ref> {{clear}} ==Electron telescopes== {{main|Instruments/Telescopes/Electrons|Electron telescopes}} [[Image:Galileo Energetic Particles Detector.jpg|thumb|right|2050px|This is an image of the Energetic Particles Detector (EPD) aboard the Galileo Orbiter. Credit: NASA.]] "[The] two bi-directional, solid-state detector telescopes [of the Galileo Orbiter are] mounted on a platform which [is] rotated by a stepper motor into one of eight positions. This rotation of the platform, combined with the spinning of the orbiter in a plane perpendicular to the platform rotation, [permits] a 4-pi [or 4π] steradian coverage of incoming [electrons]. The forward (0 degree) ends of the two telescopes [have] an unobstructed view over the [4π] sphere or [can] be positioned behind a shield which not only [prevents] the entrance of incoming radiation, but [contains] a source, thus allowing background corrections and in-flight calibrations to be made. ... The 0 degree end of the [Low-Energy Magnetospheric Measurements System] LEMMS [uses] magnetic deflection to separate incoming electrons and ions. The 180 degree end [uses] absorbers in combination with the detectors to provide measurements of higher-energy electrons ... The LEMMS [provides] measurements of electrons from 15 keV to greater than 11 MeV ... in 32 rate channels."<ref name=Williams>{{ cite book |author=Donald J. Williams |title=Energetic Particles Detector (EPD) |publisher=NASA Goddard Space Flight Center |location=Greenbelt, Maryland USA |monthdate=May 14,⏎ |year= 2012 |url=http://nssdc.gsfc.nasa.gov/nmc/experimentDisplay.do?id=1989-084B-06 |accessdate=2012-08-11 }}</ref> {{clear}} ==Positron telescopes== {{main|Instruments/Telescopes/Positrons|Positron telescopes}} [[Image:509305main GBM positron event 300dpi.jpg|thumb|right|2050px|Observation of positrons from a terrestrial gamma ray flash is performed by the Fermi gamma ray telescope. Credit: NASA Goddard Space Flight Center.]] The image at right contains a picture of the Fermi gamma-ray telescope that performed observations of positrons from their terrestrial gamma-ray flashes. The positrons are not directly observed by the INTEGRAL space telescope, but "the 511 keV positron annihilation emission is".<ref name= Weidenspointner >{{ cite journal |author=G. Weidenspointner, G.K. Skinner, P. Jean, J. Knödlseder, P. von Ballmoos, R. Diehl, A. Strong, B. Cordier, S. Schanne, C. Winkler |title=Positron astronomy with SPI/INTEGRAL |journal=New Astronomy Reviews |month=October |year=2008 |volume=52 |issue=7-10 |pages=454-6 |url=http://www.sciencedirect.com/science/article/pii/S1387647308001164 |arxiv= |bibcode= |doi=10.1016/j.newar.2008.06.019 |pmid= |accessdate=2011-11-25 }}</ref> {{clear}} ==Neutrinos telescopes== {{main|Instruments/Telescopes/Neutrinos|Neutrinos telescopes}} [[Image:Antares Neutrinoteleskop.jpg|thumb|right|250px|An artist illustration of the Antares neutrino detector and the [[w:Nautile|Nautile]]. Credit: .]] [[Image:Icecube-architecture-diagram2009.PNG|thumb|left|2050px|This is an architecture diagram of IceCube. Credit: [[w:User:Nasa-verve|Nasa-verve]].]] '''ANTARES''' [illustrated at right] is the name of a [[w:neutrino detector|neutrino detector]] residing 2.5 km under the [[w:Mediterranean Sea|Mediterranean Sea]] off the coast of Toulon, France. It is designed to be used as a directional ''Neutrino Telescope'' to locate and observe neutrino flux from cosmic origins in the direction of the [[w:Southern Hemis(contracted; show full) |bibcode = 2009NIMPA.601..294T |arxiv=0810.4930 }}</ref> IceCube was completed on 18 December, 2010, New Zealand time.<ref>[http://icecube.wisc.edu/ IceCube Neutrino Observatory<!-- Bot generated title -->]</ref> {{clear}} ==Gamma-ray telescopes== {{main|Instruments/Telescopes/Gamma rays|Gamma-ray telescopes}} [[Image:Comptel.png|thumb|left|2 050px|The Imaging Compton Telescope (COMPTEL) utilizes the Compton Effect and two layers of gamma-ray detectors. Credit: NASA.]] [[Image:GLAST on the payload attach fitting.jpg|thumb|right|2050px|The Fermi Gamma-ray Space Telescope sits on its payload attachment fitting. Credit: NASA/Kim Shiflett.]] The '''Imaging Compton Telescope''', ('''COMPTEL''') by the [[w:Max Planck Institute for Extraterrestrial Physics|Max Planck Institute for Extraterrestrial Physics]], the [[w:University of New Hampshire|University of New Hampshire]], [[w:Netherlands Institute for Space Research|Netherlands Institute for Space Research]], and ESA's Astro(contracted; show full)t. This photon is then absorbed by NaI crystals in the lower detectors. The instrument records the time, location, and energy of the events in each layer of detectors which makes it possible to determine the direction and energy of the original gamma-ray photon and reconstruct an image and energy spectrum of the source."<ref name=Gehrels>{{ cite book |author=Neil Gehrels |title=The Imaging Compton Telescope (COMPTEL) |publisher=NASA Goddard Space Flight Center |location=Greenbelt, Maryland USA | monthdate=August 1,⏎ |year= 2005 |url=http://heasarc.gsfc.nasa.gov/docs/cgro/cgro/comptel.html |accessdate=2013-04-05 }}</ref> The Large Area Telescope (LAT) [of the [[w:Fermi Gamma-ray Space Telescope|Fermi Gamma-ray Space Telescope]] ] detects individual gamma rays using technology similar to that used in terrestrial [[w:particle accelerator|particle accelerator]]s. [[w:Photons|Photons]] hit thin metal sheets, converting to electron-positron pairs, via a process known as [[w:pair production|pair production]]. These charged pa(contracted; show full) "For X-rays, the index of refraction is defined by Rayleigh scattering,"<ref name=Wogan>{{ cite book |author=Tim Wogan |title=Silicon 'prism' bends gamma rays |publisher=Institute of Physics |location= | monthdate=May 9,⏎ |year= 2012 |url=http://physicsworld.com/cws/article/news/2012/may/09/silicon-prism-bends-gamma-rays |pdf=⏎ |accessdate=2013-05-09 }}</ref> especially in the use of Wolter telescopes. "[T]he strength of the effect drops off as the inverse square of the X-ray energy. This means that at high X-ray energies – and on into low gamma-ray energies – the radiation is not bent enough for a lens to work effectively."<ref name=Wogan/> "[T]he index of refraction starts to make a comeback at energies greater than about 700 keV. What is more, while the index of refraction is negative for X-rays, it becomes positive for gamma rays."<ref name=Wogan/> "What is new now is that with gamma rays we can really address the extremely high electric field of the nucleus," with Delbrück scattering.<ref name=Habs>{{ cite book |author=Dietrich Habs |title=Silicon 'prism' bends gamma rays |publisher=Institute of Physics |location= |monthdate=May 9,⏎ |year= 2012 |url=http://physicsworld.com/cws/article/news/2012/may/09/silicon-prism-bends-gamma-rays |accessdate=2013-05-09 }}</ref> "The measurements indicate that there exists an index of refraction for gamma-ray energies that is substantially larger than people believed before".<ref name=Pietralla>{{ cite book |author=Norbert Pietralla |title=Silicon 'prism' bends gamma rays |publisher=Institute of Physics |location= |monthdate=May 9,⏎ |year= 2012 |url=http://physicsworld.com/cws/article/news/2012/may/09/silicon-prism-bends-gamma-rays |accessdate=2013-05-09 }}</ref> "Materials with nuclei that have a large positive charge – such as gold – should be ideal for making gamma-ray lenses".<ref name=Wogan/> {{clear}} ==X-ray telescopes== {{main|Instruments/Telescopes/X-rays|X-ray telescopes}} [[Image:Xrtlayout.gif|thumb|right|2050px|The XRT uses a grazing incidence Wolter 1 telescope to focus X-rays onto a state-of-the-art CCD. Credit: .]] X-ray telescopes can use a variety of different designs to image X-rays. The most common methods used in X-ray telescopes are grazing incidence mirrors and coded apertures. The limitations of X-ray optics result in much narrower fields of view than visible or UV telescopes. An extreme example of a reflecting telescope is demonstrated by the grazing incidence X-ray telescope (XRT) of the [[w:Swift Gamma-Ray Burst Mission|Swift]] satellite that focuses X-rays onto a state-of-the-art charge-coupled device (CCD), in red at the focal point of the grazing incidence mirrors (in black at the right). A '''Wolter telescope''' is a telescope for X-rays using only grazing incidence optics. X-rays mirrors can be built, but only if the angle from the plane of reflection is very low (typically 10 arc-minutes to 2 degrees)<ref name="Pal Singh, 2005" >{{cite book |url=http://www.ias.ac.in/resonance/June2005/pdf/June2005p15-23.pdf ⏎ |author=Kulinder Pal Singh |title=Techniques in X-ray Astronomy |archiveurl=http://web.archive.org/web/20120919153449/http://www.ias.ac.in/resonance/June2005/pdf/June2005p15-23.pdf|archiveccessdate=2012-09-19}}</ref>. These are called ''glancing (or grazing) incidence mirrors''. In 1952, Hans Wolter outlined three ways a telescope could be built using only this kind of mirror.<ref name=WolerGIM>{{ cite journal |title=Glancing Incidence Mirror Systems as Imaging Optics for X-rays |author=Hans Wolter |journal=Ann. Physik |volume=10 |pages=94 |year=1952 |ref=Wolter, Glancing Incidence Mirror Systems, 1952 }}</ref><ref name=WolterGMS>{{ cite journal |title=A Generalized Schwarschild Mirror Systems For Use at Glancing Incidence for X-ray Imaging |author=Hans Wolter |journal=Ann. Physik |volume=10 |pages=286 |year=1952 |ref=Wolter, Generalized Schwarschild Mirror System, 1952 }}</ref>. Not surprisingly, these are called Wolter telescopes of type I, II, and III. Each has different advantages and disadvantages.<ref name=Petre>{{ cite book |author=Rob Petre |url=http://imagine.gsfc.nasa.gov/docs/science/how_l2/xtelescopes_systems.html |title=X-ray Imaging Systems |publisher=NASA⏎ |ref=Petre, X-ray Imaging Systems }}</ref> {{clear}} ==Optical telescopes== {{main|Instruments/Telescopes/Opticals|Optical telescopes}} [[Image:HST-SM4.jpeg|thumb|right|2050px|The Hubble Space Telescope is seen from the departing Space Shuttle Atlantis, flying Servicing Mission 4 (STS-125), the fifth and final human spaceflight to visit the observatory. Credit: Ruffnax (Crew of STS-125).]] [[Image:HaleTelescope-MountPalomar.jpg|thumb|left|2050px|Mt.Palomar's 200-inch Telescope, pointing to the zenith, is seen from the east side. Note the person standing below the telescope (center-right at the bottom of the image). Credit: NASA.]] '''Def.''' a [[wikt:monocular|monocular]] [[wikt:optical|optical]] [[wikt:instrument|instrument]] possessing [[wikt:magnification|magnification]] for observing distant objects is called a '''telescope'''. The [[w:Hubble Space Telescope|Hubble Space Telescope]] (HST) is an excellent example of a [[Radiation satellites|radiation astronomy satellite]] designed for more than one purpose: the various astronomies of [[optical astronomy]]. The HST is an optical astronomy telescope that “incorporated a set of 48 filters isolating spectral lines of particular astrophysical interest. Most radiation telescopes, especially optical telescopes, combine a variety of lenses, mirrors, active and adaptive optics, filters, detectors, mounts, image processing, and observatories, in many locations. {{clear}} ==Active optics== {{main|Physics/Optics/Actives|Active optics}} [[Image:GTC Active Optics Acutators.jpg|thumb|right|2050px|Actuators are part of the active optics of the ''[[w:Gran Telescopio Canarias|''Gran Telescopio Canarias]]'']]. Credit: .]] '''Active optics''' is a [[w:technology|technology]] used with [[w:reflecting telescope|reflecting telescope]]s developed in the 1980s<ref name=Hardy>{{ cite journalbook |author=John W. Hardy |title=Active optics: A new technology for the control of light⏎ |year=1977 |month=June |series=, In: ''Proceedings of the IEEE'' |date=June 1977 |pages=110 |url=http://oai.dtic.mil/oai/oai?verb=getRecord&metadataPrefix=html&identifier=ADA339170 |bibcode=1978IEEEP..66..651H }}</ref>, which actively shapes a telescope's [[w:mirror|mirror]]s to prevent deformation due to external influences such as wind, temperature, mechanical stress. Without active optics, the construction of 8 metre class telescopes is not possible, nor would telescopes with segmented mirrors be feasible. (contracted; show full)rimary) in its optimal shape against all environmental factors such as [[w:gravity|gravity]] (at different telescope inclinations), wind, temperature changes, telescope axis deformation, et cetera. Active optics correct all factors that may affect image quality at timescales of one second or more. The telescope is therefore ''actively'' still, in its optimal shape. {{clear}} ==Adaptive optics== {{main|Physics/Optics/Adaptives|Adaptive optics}} [[Image:GRAAL instrument.jpg|thumb|right|2 050px|This image shows some of the GRAAL instrument team inspecting GRAAL’s mechanical assembly. Credit: ESO.]] '''Def.''' an optical system in telescopes that reduces atmospheric distortion by dynamically measuring and correcting wavefront aberrations in real time, often by using a deformable mirror is called '''adaptive optics'''. "Already it has allowed ground-based telescopes to produce images with sharpness rivalling those from the Hubble Space Telescope. The technique is expected to revolutionize the future of ground-based optical astronomy."<ref name=Roddier>{{ cite book |author=François Roddier |title=Adaptive Optics in Astronomy |publisher=Cambridge University Press |location=Cambridge, United Kingdom |month= |year=1999 |editor=François Roddierdate=1999 |pages=411 |url=http://books.google.com/books?hl=en&lr=&id=4n5tBN21LRsC&oi=fnd&pg=PP1&ots=7FUaBW-y4B&sig=1NLsHH3qkTKN4yA4dD1C5YqxZhg |arxiv= |bibcode= |doi= |pmid= |isbn=0 521 55375 X |pdf=http://catdir.loc.gov/catdir/samples/cam031/00500597.pdf⏎ |accessdate=2012-02-15 }}</ref> At right is an image of the adaptive optics of the GRAAL. GRAAL stands for GRound layer Adaptive optics Assisted by Lasers. It will use the technique of adaptive optics to improve the quality of images by compensating for turbulence in the lower layers of the atmosphere, up to an altitude of 1 kilometre. GRAAL, which will be installed on ESO’s Very Large Telescope (VLT) on Cerro Paranal in Chile, is designed to improve the vision of the VLT’s already excellent HAWK-I camera even further. Currently, HAWK-I operates without adaptive optics. Installing GRAAL will improve the sharpness of HAWK-I’s images, and reduce the exposure times needed by up to a factor of two. {{clear}} ==Refracting telescopes== {{main|Instruments/Telescopes/Refracting|Refracting telescopes}} [[Image:Kepschem.png|thumb|right|2050px|This is a schematic of a Keplerian refracting telescope which uses two different sizes of planoconvex lenses. Credit: .]] The '''Keplerian Telescope''', invented by [[w:Johannes Kepler|Johannes Kepler]] in 1611, is an improvement on Galileo's design.<ref name=Tunnacliffe>{{ cite book |title= Optics |author= AH Tunnacliffe, JG Hirst |yeardate= 1996 |publisher= |location= Kent, England |isbn= 0-900099-15-1 |pages= 233–7 |url= }}</ref> It uses a [plano]convex lens as the eyepiece instead of Galileo's double concave one. The advantage of this arrangement is [that] the rays of light emerging from the eyepiece are converging. This allows for a much wider [[w:field of view|field of view]] and greater eye relief but the image for the viewer is inverted. Considerably higher magnifications can be reached with this design but to overcome [[w:Optical aberration|aberration]]s the simple objective lens needs to have a very high [[w:Focal ratio|f-ratio]]. All refracting telescopes use the same principles. The combination of an [[w:objective (optics)|objective]] [[w:lens (optics)|lens]] '''1''' and some type of [[w:eyepiece|eyepiece]] '''2''' is used to gather more light than the human eye could collect on its own, focus it '''5''', and present the viewer with a [[w:brightness|brighter]], [[w:clarity|clearer]], and [[w:magnification|magnified]] [[w:virtual image|virtual image]] '''6'''. {{clear}} ==Reflecting telescopes== {{main|Instruments/Telescopes/Reflecting|Reflecting telescopes}} [[Image:SOFIA 2.5M Primary Mirror.jpg|thumb|left|2050px|The [[NASA]] logo on Bldg. 703 at the Dryden Aircraft Operations Facility in Palmdale, California, is reflected in the 2.5 m primary mirror of the SOFIA observatory's telescope. Credit: .]] [[Image:Franklin reflector 24.jpg|right|thumb|2050px|24 inch convertible Newtonian/Cassegrain reflecting telescopeis shown on display at the [[w:Franklin Institute|Franklin Institute]]. Credit: .]] A '''reflecting telescope''' (also called a '''reflector''') is an [[w:optical telescope|optical telescope]] which uses a single or combination of [[w:curved mirror|curved mirror]]s that reflect [[w:light|light]] and form an [[w:image|image]]. {{clear}} ==Catadioptric telescopes== {{main|Instruments/Telescopes/Catadioptrics|Catadioptric telescopes}} '''Def.''' optical systems that employ both refractive (dioptric) and reflective (catoptric) elements are called '''catadioptric optical systems'''. '''Def.''' the construction and use of catadioptric lenses and systems is called '''catadioptrics'''. ==Dobsonian telescopes== {{main|Instruments/Telescopes/Dobsonians|Dobsonian telescopes}} [[Image:Red dobsonian.jpg|thumb|right|2050px|This is a red Dobsonian telescope on display at Stellafane in the early 1980s. Credit: .]] A '''Dobsonian telescope''' is an alt-azimuth mounted newtonian telescope design popularized by the [amateur astronomy] John Dobson starting in the 1960s. Dobson's telescopes featured a simplified mechanical design that was easy to manufacture from readily available components to create a large, portable, low-cost telescope. The design is optimized for visually observing faint deep sky objects such as nebulae. This type of observation requires a large objective diameter (i.e. light-gathering power) of relatively short focal length and portability for travel to relatively less light polluted locations.<ref name="books.google.com">[http://books.google.com/books?id=l2TNnHkdDpkC&pg=PA286&lr=#PPA287,M1 Jack Newton, Philip Teece - "'''The Guide to Amateur Astronomy'''" - Page 287]</ref><ref>[http://books.google.com/books?id=9gUjaCMlX5oC&pg=PA37&dq=dobsonian+amateur+telescope+makers&lr= Timothy Ferris "'''Seeing in the Dark'''" - Page 39]</ref> {{clear}} ==Schmidt telescopes== {{main|Instruments/Telescopes/Schmidt|Schmidt telescopes}} [[Image:Schmidt telescope (PSF).svg|thumb|2050px|right|The diagram illustrates the optical ray paths inside a Schmidt telescope. Credit: .]] [[Image:Alfred-Jensch-Teleskop.jpg|thumb|2050px|left|The 2 meter diameter (Alfred-Jensch-Telescope at the Karl Schwarzschild Observatory in Tautenburg, Thuringia, Germany, is the largest '''Schmidt camera''' in the world. Credit: .]] At the top of this lecture/article is the Schmidt Telescope at the former Brorfelde Observatory. It is now used by amateur astronomers. The telescope from 1966 is still located in the same building in Brorfelde as originally. Today the telescope has a 77 cm mirror and a digital 2048x2048 pixel CCD-camera. Originally photographic film was used, and in the lower right part an engineer is showing the former film-box, which was then placed behind the locker at the center of the telescope (at the prime focus). A '''Schmidt camera''', also referred to as the '''Schmidt telescope''', is a catadioptric astrophotographic optical telescope designed to provide wide fields of view with limited aberrations. {{clear}} ==Maksutov telescopes== {{main|Instruments/Telescopes/Maksutovs|Maksutov telescopes}} [[Image:Maksutov 150mm.jpg|right|thumb|2050px|A 150mm aperture Maksutov–Cassegrain telescope is shown. Credit: .]] [[Image:Maksutov spot cassegrain.png|right|thumb|2050px|Light path in a typical "Gregory" or "spot" Maksutov–Cassegrain is diagrammed. Credit: .]] "The '''Maksutov''' is a catadioptric telescope design that combines a spherical mirror with a weakly negative meniscus lens in a design that takes advantage of all the surfaces being nearly "spherically symmetrical".<ref name=Savard>{{ cite book |author=John J. G. Savard |title='Miscellaneous Musings (contracted; show full) The multilayer technology allows conventional telescope forms (such as the Cassegrain or Ritchey-Chretien designs) to be used in a novel part of the spectrum. ==Visual telescopes== {{main|Instruments/Telescopes/Visuals|Visual telescopes}} [[Image:USNO Refractor 1904.jpg|thumb|right|2 050px|This image shows the 26-inch Warner & Swasey refracting telescope at the United States Naval Observatory. Credit: Waldon Fawcett.]] “I think everyone can conjure up a mental image of astronomers at every level and place in history, gazing through the eyepieces of their telescopes at sights far away - true visual astronomy.”<ref name=Cooke>{{ cite book |author=Antony Cooke |title=Visual Astronomy Under Dark Skies: A New Approach to Observing Deep Space |publisher=Springer-Verlag |location=London |month= |yeardate=2005 |editor= |pages=180 |url=http://books.google.com/books?id=SXmrBfl4H3sC&dq=entity+astronomy&lr=&source=gbs_navlinks_s |bibcode= |doi= |pmid= |isbn=1852339012 |accessdate=2011-11-06 }}</ref> {{clear}} ==Astronomical filters== {{main|Filters/Astronomy|Astronomical filters}} [[Image:Dichroic filters.jpg|thumb|right|2050px|[[w:Ultraviolet|Ultraviolet]] filters are used in astronomy for blocking this part of the spectrum, which causes the camera to heat up when photographing without affecting the image. Credit: .]] (contracted; show full) observation of the [[w:planets|planets]] and the [[Moon]], polarizing filters work by adjusting the brightness, and are usually used for the Moon. The broadband and narrowband filters transmit the wavelengths that are emitted by ... [[w:Hydrogen|hydrogen]] and [[w:Oxygen|oxygen]] atoms, and are frequently used for reducing [[w:light pollution|light pollution]].[1] {{clear}} ==Infrared telescopes== {{main|Instruments/Telescopes/Infrareds|Infrared telescopes}} [[Image:Spitzer- Telescopio.jpg|thumb|right|2 050px|The image shows the Spitzer Space Telescope prior to launch. Credit: NASA/JPL/Caltech.]] [[Image:Diagram Reflector RitcheyChretien.svg|thumb|right|2050px|The diagram is of a Ritchey-Chrétien reflector telescope. Credit: .]] [[Image:NOFS 40inch03.jpg|thumb|left|2050px|This is an early Ritchey-Chrétien reflector telescope. Credit: P. Shankland.]] The Spitzer telescope is a Ritchey–Chrétien telescope a specialized Cassegrain telescope that has a hyperbolic primary mirror and a hyperbolic secondary mirror designed to eliminate optical errors (coma). They have [a] large field of view free of optical errors compared to a more conventional reflecting telescope configuration. (contracted; show full) :<math>K_1 = -1 - \frac{2}{M^3}\cdot\frac{B}{D}</math> and :<math>K_2 = -1 - \frac{2}{(M - 1)^3}\left[M(2M - 1) + \frac{B}{D}\right]</math> where <math>M = F/f_1 = (F - B)/D</math> is the secondary magnification.<ref name=Smith>{{ cite book |author=Warren J. Smith | yeardate=2008 |title=Modern Optical Engineering |pages=508–10 |edition=4th |publisher=McGraw-Hill Professional |isbn=978-0-07-147687-4 }}</ref> Note that <math>K_1</math> and <math>K_2</math> are less than <math>-1</math> (since <math>M>1</math>), so both mirrors are hyperbolic. (The primary mirror is typically quite close to being parabolic, however.) The hyperbolic curvatures are difficult to test, especially with equipment typically available to amateur telescope makers or laboratory-scale fabricators; thus, older telescope layouts predominate in these applications. However, professional optics fabricators and large research groups test their mirrors with [[w:interferometer|interferometer]]s. A Ritchey–Chrétien then requires minimal additional equipment, typically a small optical device called a [[w:null corrector|null corrector]] that makes the hyperbolic primary look spherical for the interferometric test. The telescope at left is the early Ritchey–Chrétien 1.0 meter telescope at NOFS at the [[w:United States Naval Observatory Flagstaff Station|United States Naval Observatory Flagstaff Station]]. ==Submillimeter telescopes== {{main|Instruments/Telescopes/Submillimeters|Submillimeter telescopes}} [[Image:Caltech-Submillimeter-Observatory (straightened).jpg|thumb|right|2050px|This photograph shows the 10.4-metre diameter submillimeter wavelength telescope of the Caltech Submillimeter Observatory (CSO). Credit: [http://www.flickr.com/people/62472689@N00 Samuel Bouchard] from Quebec City, Canada; modified by [[commons:User:Huntster|Huntster]].]] [[Image:Four antennas ALMA.jpg|thumb|left|2050px|Four antennas of the Atacama Large Millimeter/submillimeter Array (ALMA) gaze up at the star-filled night sky. Credit: ESO/José Francisco Salgado (josefrancisco.org).]] [[Image:SMT 1.png|thumb|right|2050px|The [[w:Heinrich Hertz Submillimeter Telescope|Heinrich Hertz Submillimeter Telescope]] is shown at night. Credit: [[w:User:Geremia|Geremia]].]] The [[w:Atacama Large Millimeter Array|Atacama Large Millimeter/submillimeter Array]] (ALMA) is being constructed at an altitude of 5000 m on the [[w:Chajnantor plateau|Chajnantor plateau]] in the [[w:Atacama Desert|Atacama Desert]] of [[w:Chile|Chile]]. This is one of the driest places on [[Earth]] and this dryness, combined with the thin atmosphere at high altitude, offers superb conditions for observing the Universe at millimetre and submillimetre wavelengths. At these long wavelengths, astronomers can probe, for example, [[w:Molecular cloud|molecular cloud]]s, which are dense regions of gas and dust where new stars are born when a cloud collapses under its own gravity. Currently, the Universe remains relatively unexplored at submillimetre wavelengths, so astronomers expect to uncover many new secr(contracted; show full)d and above Mt. Graham is particulatly vital for [[w:Extremely high frequency|EHF]] (extremely low wavelength radio) and far-[[w:infrared|infrared]] observations - a region of the [[w:electromagnetic spectrum|spectrum]] where the [[w:electromagnetic wave|electromagnetic wave]]s are strongly [[w:attenuation|attenuated]] by any [[w:water vapor|water vapor]] or clouds in the air. {{clear}} ==Radio telescopes== {{main|Instruments/Telescopes/Radios|Radio telescopes}} [[Image:parkes.arp.750pix.jpg|thumb|right|2 050px|This 64 meter radio telescope is at [[w:Parkes Observatory|Parkes Observatory]] Credit: John Sarkissian (CSIRO Parkes Observatory).]] '''Def.''' “a device for studying astronomical sources of radio waves”<ref name=SemperBlotto>{{ cite book |author=[[wikt:User:SemperBlotto|SemperBlotto]] |title=radio telescope |publisher=Wikimedia Foundation, Inc |location=San Francisco, California |monthdate=4 September⏎ |year= 2015 |url=https://en.wiktionary.org/wiki/radio_telescope |accessdate=2015-09-18 }}</ref> is called a '''radio telescope'''. A '''radio telescope''' is a form of [[w:Directional antennae|directional]] [[radio]] [[w:Antenna (radio)|antenna]], as used in tracking and collecting data from [[w:satellite|satellite]]s and [[w:space probe|space probe]]s that [operates] in the [[w:radio frequency|radio frequency]] portion of the [[w:electromagnetic spectrum|electromagnetic spectrum]]. Radio telescopes are typically large [[w:Parabolic antenna|parabolic]] ("dish") antennas used singly or in an array. Radio [[w:observatory|observatories]] are preferentially located far from major centers of population to avoid [[w:electromagnetic interference|electromagnetic interference]] (EMI) from radio, [[w:TV|TV]], [[w:radar|radar]], and other EMI emitting devices. {{clear}} ==Microwave telescopes== {{main|Instruments/Telescopes/Microwaves|Microwave telescopes}} [[Image:RTEmagicC Planck satellite 01.jpg|thumb|right|2050px|The Planck telescope was launched in 2009 to observe the Cosmic Microwave Background Radiation. Credit: ESA.]] "The basic scientific goal of the Planck mission is to measure [cosmic microwave background] CMB anisotropies at all angular scales larger than 10 arcminutes over the entire sky with a precision of ~2 parts per million. The model payload consists of a 1.5 meter off-axis telescope with two focal plane arrays of detectors sharing the focal plane. Low frequencies will be covered by 56 tuned radio receivers sensitive to 30-100 GHz, while high frequencies will be covered by 56 bolometers sensitive to 100-850 GHz."<ref name=Chuss>{{ cite book |author=David T. Chuss |title=The Planck Mission |publisher=Goddard Space Flight Center |location=Greenbelt, Maryland USA |monthdate=April 18,⏎ |year= 2008 |url=http://lambda.gsfc.nasa.gov/product/space/p_overview.cfm |accessdate=2013-12-12 }}</ref> {{clear}} ==Radar telescopes== {{main|Instruments/Telescopes/Radars|Radar telescopes}} [[Image:ADU-1000-3.jpg|thumb|2050px|right|This image shows the early planetary radar at [[w:Pluton (complex)|Pluton]], USSR, 1960. Credit: [[commons:User:Rumlin|Rumlin]].]] [[Image:Arecibo Observatory Aerial View2.jpg|thumb|left|2050px|The Arecibo Radio Telescope, Arecibo, Puerto Rico, at 1000 feet (305 m) across, is the largest dish antenna in the world. Credit: H. Schweiker/WIYN and NOAO/AURA/NSF, NOAA.]] [[Image:Evpatori.jpg|thumb|2050px|left|The image is of the Evpatoria RT-70 radar telescope in the Ukraine. Credit: Bebo.]] [[Image:TerraSAR-X and TanDEM-X.jpg|thumb|right|2050px|In this artist's impression TerraSAR-X and TanDEM-X are in orbit. Credit: Astrium GmbH.]] The image at right shows planetary radar telescopes at [[w:Pluton (complex)|Pluton]], USSR, in 1960. The "Arecibo Observatory in Puerto Rico [is] the world's largest, and most sensitive, single-dish radio telescope."<ref name=Brand>{{ cite book | author=David Brand (contracted; show full)At second lower left is the Evpatoria RT-70 radar telescope in the Ukraine. At lower right is an artist's impression of the two radar satellites TerraSAR-X and TanDEM-X. {{clear}} ==Radio interferometry== {{main|Instruments/Interferometers/Radios|Radio interferometry}} [[Image:Interf diagram.gif|thumb|right|2 050px|The diagram shows a possible layout for an astronomical interferometer, with the mirrors laid out in a parabolic arrangement (similar to the shape of a conventional telescope mirror). Credit: .]] (contracted; show full)|url=http://www.pparc.ac.uk/frontiers/latest/feature.asp?article=14F1&style=feature |title = The electromagnetic spectrum |publisher = Particle Physics and Astronomy Research Council |accessdate = 17 August 2006 }}</ref> ==Plasma-object telescopes== {{main|Instruments/Telescopes/Plasma objects|Plasma-object telescopes}} [[Image:HallThruster 2.jpg|thumb|2 50px|2 kW Hall thruster is in operation as part of the Hall Thruster Experiment at the Princeton Plasma Physics Laboratory. Credit: [[w:User:Dstaack|Dstaack]].]] [[Image:Xenon hall thruster.jpg|thumb|250px|This is a xenon 6 kW Hall thruster in operation at the NASA Jet Propulsion Laboratory. Credit: NASA/JPL-Caltech.]] In [[w:spacecraft propulsion|spacecraft propulsion]], a '''Hall thruster''' is a type of [[w:ion thruster|ion thruster]] in which the [[w:propellant|propellant]] is accelerated by an [[w:electric field|electric field]]. Hall thrusters trap electrons in a magnetic field and then use the electrons to ionize propellant, efficiently accelerate the ions to produce thrust, and neutralize the ions in the plume. Hall thrusters are sometimes referred to as '''Hall effect thrusters''' or '''Hall current thrusters'''. Hall thrusters are often regarded as a moderate [[w:specific impulse|specific impulse]] (1,600 s) [[w:space propulsion|space propulsion]] technology. ... Hall thrusters operate on a variety of propellants, the most common being xenon. Other propellants of interest include krypton, argon, bismuth, iodine, magnesium, and zinc. While these thrusters are not plasma-object telescopes, they may serve to maneuver or slew a space telescope. As sources of blue light they mat serve as calibrated light sources. {{clear}} ==Gaseous-object telescopes== {{main|Instruments/Telescopes/Gaseous objects|Gaseous-object telescopes}} [[Image:Sun Gun.jpg|thumb|right|2050px|This is an image of a Sun Gun Telescope. Credit: .]] The '''Sun Gun Telescope''' is designed so that large groups of people can view the [[Sun (star)|sun]] safely - in particular it was created as a way to encourage children to become interested in [[astronomy]]. With this safe and portable device, both amateur science enthusiasts and professionals alike can observe sun spots. The Sun Gun has a 60mm dia. 900mm fl. optical tube which is mounted inside a 3" PVC which is in turn connected to a 20" plastic flower planter. A rear projection screen is mounted on the top of the flower planter. The entire Sun Gun can be made from items easily found at most local hardware stores. The scope itself is an inexpensive 60mm refractor available from many sources. {{clear}} ==Liquid-object telescopes== {{main|Instruments/Telescopes/Liquid objects|Liquid-object telescopes}} [[Image:Liquid Mirror Telescope.jpg|thumb|right|250px|This is a liquid mirror telescope. Credit: .]] '''Liquid mirror telescopes''' are telescopes with mirrors made with a reflective liquid. The most common liquid used is mercury, but other liquids will work as well (for example, low melting alloys of gallium). The container for the liquid is rotating so that the liquid assumes a paraboloidal shape. A paraboloidal shape is precisely the shape needed for the primary mirror of a telescope. The rotating liquid assumes the paraboloidal shape regardless of the container's shape. To reduce the amount of liquid metal needed, and thus weight, a rotating mercury mirror uses a container that is as close to the necessary parabolic shape as possible. Liquid mirrors can be a low cost alternative to conventional large telescopes. Compared to a solid glass mirror that must be cast, ground, and polished, a rotating liquid metal mirror is much less expensive to manufacture. A telescope with a liquid metal mirror can only be used [as a] zenith telescope that looks straight up. {{clear}} ==Hydrogen telescopes== {{main|Instruments/Telescopes/Hydrogens|Hydrogen telescopes}} [[Image:Solarborg.jpg|right|thumb|2050px|Here is an example of an amateur solar telescope equipped with a hydrogen-alpha filter system. Credit: .]] In the field of [[amateur astronomy]] amateurs use hydrogen-alpha filter systems. {{clear}} ==Alloys== {{main|Chemicals/Alloys|Alloys}} [[Image:Cloudcroft Observatory.jpg|thumb|right|2050px|The image shows the dome of the NASA Orbital Debris Observatory near Cloudcroft, New Mexico. Credit: NASA.]] [[Image:CCD_Debris_Telescope.png|thumb|left|2050px|This image shows the CCD Debris Telescope that is under the NODO dome. Credit: ]] The NASA-LMT was 3 m (9.8 ft) aperture liquid mirror telescope located in NODO's main dome. It consisted of a 3 m diameter parabolic dish that held 4 U.S. gallons (15 l) of a highly reflective liquid metal, mercury, spinning at a rate of 10 rpm, with sensors mounted above on a fixed structure. Due to the primary mirror's material, the NASA-LMT was configured as a zenith telescope. Using 20 narrowband filters, it cataloged space debris in Earth's orbit. The 32 cm (13 in) CCD Debris Telescope (CDT) was a portable Schmidt camera equipped with a 512×512 pixel charge-coupled device (CCD) sensor. It operated at NODO from October of 1997 until December of 2001, and was used to characterize debris at or near geosynchronous orbit. {{clear}} ==Meteorites== {{main|Rocks/Meteorites|Meteorites}} [[Image:Carancas Meteorite 2.jpg|thumb|right|2050px|The image contains a 27.70 g fragment of the Carancas meteorite fall. The scale cube is 1 cm<sup>3</sup>. Credit: Meteorite Recon.]] On September 20, the X-Ray Laboratory at the Faculty of Geological Sciences, Mayor de San Andres University, [[w:La Paz, Bolivia|La Paz, Bolivia]], published a report of their analysis of a small sample of material recovered from the impact site. They detected iron, nickel, cobalt, and traces of iridium — elements characteristic of the elemental compo(contracted; show full)[[w:electromagnetic spectrum|spectrum]] of [[w:electromagnetic radiation|electromagnetic radiation]], including visible light, which [[w:radiant energy|radiates]] from [[w:star|star]]s and other celestial objects. Spectroscopy can be used to derive many properties of distant stars and galaxies, such as their chemical composition, but also their motion by [[w:Doppler shift|Doppler shift]] measurements. ==Spectrometers== {{main|Radiation astronomy/Spectrometers|Spectrometers}} [[Image:Osse.gif|thumb|right|2 050px|The Oriented Scintillation Spectrometer Experiment (OSSE) consists of four NaI scintillation detectors, sensitive to energies from 50 keV to 10 MeV. Credit: NASA GSFC.]] "The Oriented Scintillation Spectrometer Experiment (OSSE) will conduct a broad range of observations in the 0.05-250 MeV energy range. Major emphasis is placed on scientific objectives in the 0.1-10.0 MeV region with a limited capability above 10 MeV, primarily for observations of solar gamma-rays and neutrons and observations of high-energy emission from pulsars."<ref name=Johnson>{{ cite book |author=W. N. Johnson |title=Appendix G to the NASA RESEARCH ANNOUNCEMENT for the COMPTON GAMMA RAY OBSERVATORY GUEST INVESTIGATOR PROGRAM |publisher=National Aeronautics and Space Administration Goddard Space Flight Center |location=Greenbelt, Maryland USA |monthdate=November⏎ |year= 1996 |url=http://heasarc.gsfc.nasa.gov/docs/cgro/nra/appendix_g.html#III.%20COMPTEL%20GUEST%20INVESTIGATOR%20PROGRAM |accessdate=2013-04-05 }}</ref> {{clear}} ==Planetary telescopes== {{main|Instruments/Telescopes/Planetary|Planetary telescopes}} [[Image:Goto telescope.jpg|thumb|right|250px|A telescope on an alt-azimuth GoTo mount. Note the keypad, resting on the platform between the tripod's legs, that is the telescope's hand control. Batteries are stored in the circular compartment just above the tripod. In this picture, the compartment is just above the hand control.]] In [[amateur astronomy]], "'''GoTo'''" refers to a type of [[telescope mount]] and related [[software]] which can automatically point a telescope to [[astronomical objects]] that the user selects. Both axes of a GoTo mount are motor driven and are controlled by either a microprocessor-based integrated controller or a personal computer, as opposed to the single axis semi-automated tracking of a traditional clock drive mount. This allows the user to command the mount to point the telescope to a right ascension and declination that the user inputs or have the mount itself point the telescope to objects in a pre-programmed data base including ones from the Messier catalogue, the New General Catalogue, and even major solar system bodies (the Sun, Moon, and planets). {{clear}} ==Solar telescopes== {{main|Instruments/Telescopes/Solar|Solar telescopes}} [[Image:Kitt Peak McMath-Pierce Solar Telescope.jpg|thumb|right|2050px|This view is of the McMath-Pierce Solar Telescope at Kitt Peak National Observatory, near Tucson, Arizona. Credit: [http://www.flickr.com/photos/oceanyamaha/ ocean yamaha].]] A '''solar telescope''' is a special purpose [[w:telescope|telescope]] used to observe the [[Sun (star)|Sun]]. Solar telescopes usually detect light with wavelengths in, or not far outside, the [[w:visible spectrum|visible spectrum]]. {{clear}} ==Asteroid telescopes== {{main|Instruments/Telescopes/Asteroids|Asteroid telescopes}} [[Image:Lowell astrograph.jpg|thumb|2050px|right|The Lowell astrograph is a dedicated astrophotography telescope. Credit: .]] The Lowell astrograph imaged at right is a 13-inch, f/5.3 astrograph at Lowell Observatory, a refractor with a 3 element Cooke triplet lens.<ref name=Tombaugh>{{ cite book |author=Clyde W. Tombaugh |title=The Struggles to Find the Ninth Planet |url=http://ircamera.as.arizona.edu/NatSci102/NatSci102/text/ext9thplanet.htm }}</ref>) that was used in the discovery of [[Pluto]]. An '''astrograph''' ('''astrographic camera''') is a telescope designed for the sole purpose of astrophotography. Astrographs are usually used in wide field surveys of the night sky as well as detection of objects such as [[asteroids]], [[, meteor]]s, and [[comet]]s. {{clear}} ==Comet-seeker telescopes== {{main|Instruments/Telescopes/Comet seekers|Comet-seeker telescopes}} A comet seeker is a type of small telescope adapted especially to searching for comets: commonly of short focal length and large aperture, in order to secure the greatest brilliancy of light. ==Stellar telescopes== {{main|Instruments/Telescopes/Stars|Stellar telescopes}} [[File:FASTT Transit Circle.jpg|thumb|right|2050px|The Ron Stone/Flagstaff Astrometric Scanning Transit Telescope of the U.S.Naval Observatory, built by Farrand Optical Company, 1981, is imaged. Credit: .]] (contracted; show full) |url=http://articles.adsabs.harvard.edu//full/1990IAUS..141..369S/0000369.000.html |title=The USNO (Flagstaff Station) CCD Transit Telescope and Star Positions Measured From Extragalactic Sources , In: ''Proceedings of IAU Symposium No. 141'' |first1=Ronald C. |last1=Stone |first2=David G. |last2=Monet |yeardate=1990 |journal=Proceedings of IAU Symposium No. 141⏎ |pages=369–370 }}</ref> {{clear}} ==Galactic telescopes== {{main|Instruments/Telescopes/Galaxies|Galactic telescopes}} [[Image:NGC 891 HST.jpg|thumb|right|2050px|NGC 891 is selected as first light. Credit: NASA.]] [[Image:LargeBinoTelescope NASA.jpg|thumb|left|2050px|This is an image of the Large Binocular Telescope with protective doors open. Credit: NASA.]] The Large Binocular Telescope at left is located on Mount Graham (10,700-foot (3,300 m)) in the Pinaleno Mountains of southeastern Arizona, and is a part of the Mount Graham International Observatory. The first image taken [shown at right] combined ultraviolet and green light, and emphasizes the clumpy regions of newly formed hot stars in the spiral arms. {{clear}} ==Locations on Earth== {{main|Locations/Earth/Geography|Locations/Earth|Locations on Earth}} [[Image:VERITAS array.jpg|thumb|right|300px|VERITAS is located at the basecamp of the Smithsonian Astrophysics Observatory's Fred Lawrence Whipple Observatory (FLWO) in southern Arizona. Credit: VERITAS.]] [[Image:Aerial View of the VLTI with Tunnels Superimposed.jpg|2050px|thumb|left|The four Unit Telescopes form the VLT together with the Auxiliary Telescopes. Credit: .]] "VERITAS (Very Energetic Radiation Imaging Telescope Array System) is a ground-based gamma-ray instrument operating at the Fred Lawrence Whipple Observatory (FLWO) in southern Arizona, USA. It is an array of four 12m optical reflectors for gamma-ray astronomy in the GeV - TeV energy range. These imaging Cherenkov [a bluish light] telescopes are deployed such that they have the highest sensitivity in the VHE energy band (50 GeV - 50 TeV), with maximum sensitivity from 100 GeV to 10 TeV. This VHE observatory effectively complements the NASA Fermi mission."<ref name=Fortin>{{ cite book |author=Pascal Fortin |title=VERITAS Very Energetic Radiation Imaging Telescope Array System |publisher=Smithsonian Astrophysical Observatory |location=Amado, Arizona USA |monthdate=April 14⏎ |year=, 2013 |url=http://veritas.sao.arizona.edu/ |accessdate=2013-06-01 }}</ref> The Collaboration between Australia and Nippon for a Gamma Ray Observatory in the Outback, (CANGAROO) is for very high energy cosmic gamma ray observation by telescope detecting Cherenkov light. It is located on the [[w:Woomera Prohibited Area|Woomera Prohibited Area]] in South Australia. <ref name=CANGAROO>{{ cite book |url=http://www.physics.adelaide.edu.au/astrophysics/cangaroo/index.html |title=The CANGAROO Project |publisher=The University of Adelaide |accessdate=17 September 2011 }}</ref> The Very Large Telescope (VLT) is a telescope operated by the European Southern Observatory on Cerro Paranal in the Atacama Desert of northern Chile. The UTs are equipped with a large set of instruments permitting observations to be performed [in] the near-ultraviolet. It includes large-field imagers, adaptive optics corrected cameras and spectrographs, as well as high-resolution and multi-object spectrographs and covers a broad spectral region, from [the] deep ultraviolet (300 nm). {{clear}} ==Recent history== {{main|History/Recent|Recent history}} [[Image:TransitCircle USNO.jpg|thumb|right|2050px|This is the 6-inch transit circle of the U.S. Naval Observatory. Credit: .]] The '''recent history''' period dates from around 1,000 b2k to present. The 6-inch transit circle [imaged at right] of the U.S. Naval Observatory was built by Warner and Swasey in 1898. {{clear}} ==Coded apertures== {{main|Radiation astronomy/Telescopes/Apertures|Coded apertures}} Some X-ray telescopes use coded aperture imaging. This technique uses a flat aperture grille in front of the detector, which weighs much less than any kind of focusing X-ray lens, but requires considerably more post-processing to produce an image. ==Mirrors== {{main|Radiation astronomy/Telescopes/Mirrors|Mirrors}} [[Image:Wolter-types.gif|thumb|right|2050px|This is a diagram of Wolter telescopes of Types I, II, and III. Credit: .]] The mirrors can be made of ceramic or metal foil.<ref name=xraysMirror>{{ cite book |title=Mirror Laboratory |url=http://astrophysics.gsfc.nasa.gov/xrays/MirrorLab/xoptics.html }}</ref> The most commonly used grazing angle incidence materials for X-ray mirrors are [[w:gold|gold]] and [[w:iridium|iridium]]. The critical reflection angle is energy dependent. For gold at 1 keV, the critical reflection angle is (contracted; show full) {{clear}} ==Modulation collimators== {{main|Radiation astronomy/Telescopes/Modulation collimators|Modulation collimators}} [[Image:Four-wire grid modulation collimator.jpeg|thumb|right|2 050px|The diagram shows the principles of operation of the four-grid modulation collimator. Credit: H. Bradt, G. Garmire, M. Oda, G. Spada, and B.V. Sreekantan, P. Gorenstein and H. Gursky.]] A modulation collimator consists of “two or more wire grids [diffraction gratings] placed in front of an X-ray sensitive Geiger tube or proportional counter.”<ref name=Bradt>{{ cite journal |author=H. Bradt, G. Garmire, M. Oda, G. Spada, and B.V. Sreekantan, P. Gorenstein and H. Gursky |title=The Modulation Collimator in X-ray Astronomy |journal=Space Science Reviews |month=September |year=1968 |volume=8 |issue=4 |pages=471-506 |url= |arxiv= |bibcode=1968SSRv....8..471B |doi=10.1007/BF00175003 |pmid= |accessdate=2011-12-10 }}</ref> Relative to the path of incident X-rays (incoming X-rays) the wire grids are placed one beneath the other with a slight offset that produces a shadow of the upper grid over part of the lower grid.<ref name=Oda>{{ cite journal |author=Minoru Oda |title=High-Resolution X-Ray Collimator with Broad Field of View for Astronomical Use |journal=Applied Optics |month=January |year=1965 |volume=4 |issue=1 |pages=143 |url=http://www.opticsinfobase.org/abstract.cfm?URI=ao-4-1-143 |arxiv= |bibcode=1965ApOpt...4..143O |doi=10.1364/AO.4.000143 |pmid= |pdf=http://www.opticsinfobase.org/ao/viewmedia.cfm?uri=ao-4-1-143&seq=0 |accessdate=2011-12-10 }}</ref> {{clear}} ==Computers== {{main|Computers}} [[Image:Lights glowing on the ALMA correlator.jpg|thumb|right|2050px|The ALMA correlator is one of the most powerful supercomputers in the world. Credit: ALMA (ESO/NAOJ/NRAO), S. Argandoña.]] "The ALMA correlator [shown at right], one of the most powerful supercomputers in the world, has now been fully installed and tested at its remote, high altitude site in the Andes of northern Chile. This view shows lights glowing on some of the racks of the correlator in the ALMA Array Operations Site Techical Building. This photograph shows one of the four quadrants of the correlator. The full system has four identical quadrants, with over 134 million processors, performing up to 17 quadrillion operations per second."<ref name=ALMAObservatory>{{ cite book |author=ALMA Observatory |title=Lights glowing on the ALMA correlator |publisher=ALMA Observatory Organization |location=Atacama, chile |monthdate=July 10,⏎ |year= 2013 |url=http://www.almaobservatory.org/en/visuals/images/the-alma-observatory/?g2_itemId=3939 |accessdate=2013-07-21 }}</ref> {{clear}} ==Telescope mounts== {{main|Instruments/Telescopes/Mounts|Telescope mounts}} A telescope mount is a mechanical structure which supports a telescope. Telescope mounts are designed to support the mass of the telescope and allow for accurate pointing of the instrument. '''Def.''' an object on which another object is attached for support is called a '''mount'''. ==Altazimuth mounts== [[Image:heliostat.jpg|right|2050px|thumb|A [[w:heliostat|heliostat]] is shown at the THÉMIS experimental station in France. The mirror rotates on an alt-azimuth mount. The pointing direction of the mirror is perpendicular to its surface. Credit: .]] (contracted; show full)add a third "polar axis" to overcome these problems, providing an hour or more of motion in the direction of [[w:right ascension|right ascension]] to allow for astronomical tracking. The design also does not allow for the use of mechanical [[w:setting circles|setting circles]] to locate astronomical objects although modern [[w:Setting circles#Digital setting circles|digital setting circles]] have removed this shortcoming. {{clear}} ==Equatorial mounts== [[Image:Stuetzmontierung.jpg|thumb|right|2 050px|An example of an equatorial mount is photographed. Credit: Peter Rucks.]] The equatorial mount has north-south "polar axis" tilted to be parallel to Earth's polar axis that allows the telescope to swing in an east-west arc, with a second axis perpendicular to that to allow the telescope to swing in a north-south arc. Slewing or mechanically driving the mounts polar axis in a counter direction to the Earth's rotation allows the telescope to accurately follow the motion of the night sky. {{clear}} ==Hexapod mounts== [[Image:DOT main mirror.jpg|thumb|right|2050px|This is an image of the top part of the Dutch Open Telescope. Credit: Tim van Werkhoven.]] Instead of the classical mounting using two axles, the mirror is supported by six extendable struts (hexapod). This configuration allows moving the telescope in all six spatial degrees of freedom and also provides a strong structural integrity. {{clear}} ==Clock drives== {{main|Clocks/Drives|Clock drives}} [[Image:Aldershot observatory 02.JPG|thumb|right|2050px|The clock drive mechanism in the pier of the german equatorial mount for the 8-inch refracting telescope at [[w:Aldershot Observatory|Aldershot Observatory]] is shown in the image. Credit: .]] (contracted; show full) |author=Guy Consolmagno, Dan M. Davis, Karen Kotash Sepp, Anne Drogin, Mary Lynn Skirvin |pages=204 }}</ref> This allows the telescope to stay [fixed] on a certain point in the sky without having to be constantly re-aimed due to the Earth's rotation. The mechanism itself used to be [[w:clockwork|clockwork]] but nowadays is usually electrically driven. Clock drives can be light and portable for smaller telescopes<ref name=Oltion>{{ cite book | author = Jerry Oltion | | title = The Trackball Mount | url = http://www.sff.net/people/j.oltion/trackball_mount.htm | accessdate = 13 March 2011 }}</ref> or can be exceedingly heavy and complex for larger ones such as the 60 inch telescope at the [[w:Mount Wilson Observatory|Mount Wilson Observatory]].<ref name=SixtyInchClock>{{ cite book |url=http://www.oldengine.org/members/levans/60clock/ |title=60 inch clock (the old Mount Wilson telescope clock drive) }}</ref> Clock-driven [[w:equatorial platform|equatorial platform]]s are sometimes used in non-tracking type mounts, such as [[w:altazimuth mount|altazimuth mount]]s.<ref name=Vogel>{{ cite book | author = Reiner Vogel | title = Circle Segment Platform (link from his English language page) | yeardate = 2007 | url = http://www.reinervogel.net/index_e.html | accessdate = 13 March 2011 }}</ref> {{clear}} ==Clocks== {{main|Clocks}} [[Image:FOCS-1.jpg|thumb|left|2050px| The FOCS 1 is a continuous cold caesium fountain atomic clock in Switzerland. Credit: .]] An '''atomic clock''' is a [[w:clock|clock]] device that uses an [[w:electronic transition|electronic transition]] [[w:frequency|frequency]] in the [[w:microwave|microwave]], [[w:light|optical]], or [[w:ultraviolet|ultraviolet]] region<ref name=McCarthy>{{ cite book |title=TIME from Earth Rotation to Atomic Physics |author=Dennis McCarthy, P. Kenneth Seidelmann |at=ch. 10 & 11⏎ |location=Weinheim |publisher=Wiley-VCH |yeardate=2009 }}</ref> of the [[w:electromagnetic spectrum|electromagnetic spectrum]] of [[w:atoms|atoms]] as a [[w:frequency standard|frequency standard]] for its timekeeping element. Atomic clocks are the most accurate [[w:time standard|time]] and [[w:frequency standard|frequency standard]]s known, and are used as [[w:primary standard|primary standard]]s for international [[w:Time dissemination|time distribution services]], to control the wave frequency of television broadcasts, and in [[w:global navigation satellite system|global navigation satellite system]]s such as [[w:GPS|GPS]]. The FOCS 1 continuous cold cesium fountain atomic clock started operating in 2004 at an uncertainty of one second in 30 million years. The clock is in Switzerland. {{clear}} ==Motion calibrators== {{main|Motion calibrators}} '''POA CALFOS''' is the improved Post Operational Archive version of the [[w:Faint Object Spectrograph|Faint Object Spectrograph]] (FOS) calibration pipeline. The current version corrects for image motion problems that have led to significant wavelength scale uncertainties in the FOS data archive. The improvements in the calibration enhance the scientific value of the data in the FOS archive, making it a more homogeneous and reliable resource. ==Detectors== {{main|Radiation astronomy/Detectors|Detectors}} [[Image:Proportional Counter Array RXTE.jpg|thumb|right|2050px|This is an image of a real X-ray detector. The instrument is called the Proportional Counter Array and it is on the [[w:Rossi X-ray Timing Explorer|Rossi X-ray Timing Explorer]] (RXTE) satellite. Credit: .]] [[Radiation detectors]] provide a signal that is converted to an electric current. The device is designed so that the current provided is proportional to the characteristics of the incident radiation. Detectors such as the X-ray detector at right collect individual X-rays (photons of X-ray light), count them, discern the energy or wavelength, or how fast they are detected. The detector and telescope system can be designed to yield temporal, spatial, or spectral information. {{clear}} ==Image processors== {{main|Instruments/Telescopes/Image processors|Image processors}} '''Def.''' "any form of information processing for which both the input and output are images"<ref name=Jaaari>{{ cite book |author=[[wikt:User:Jaaari|Jaaari]] |title=image processing |publisher=Wikimedia Foundation, Inc |location=San Francisco, California |monthdate=20 February⏎ |year= 2007 |url=https://en.wiktionary.org/wiki/image_processing |accessdate=2016-07-14 }}</ref> is called '''image processing'''. '''Def.''' a representation of anything upon canvas, paper, or other surface” is called a '''picture'''. '''Def.''' a "representation of a real object"<ref name=Emperorbma>{{ cite book |author=[[wikt:User:Emperorbma|Emperorbma]] |title=image |publisher=Wikimedia Foundation, Inc |location=San Francisco, California |monthdate=1 December⏎ |year= 2004 |url=https://en.wiktionary.org/wiki/image |accessdate=2016-07-14 }}</ref> is called an '''image'''. '''Def.''' the set of points that map to a given point (or set of points) under a specified function is called an '''inverse image'''. (contracted; show full) | date = October 1999 | location = Cambridge | page = 461 | isbn = 0-521-64222-1}}</ref> ==Robotic telescopes== {{main|Instruments/Telescopes/Robotics|Robotic telescopes}} [[Image:El Enano robotic telescope.jpg|thumb|right|2 050px|“El Enano” is a robotic telescope. Credit: .]] A '''robotic telescope''' is an astronomical telescope and detector system that makes observations without the intervention of a human. In astronomical disciplines, a telescope qualifies as robotic if it makes those observations without being operated by a human, even if a human has to initiate the observations at the beginning of the night, or end them in the morning. A robotic telescope is distinct from a remote telescope, though an instrument can be both robotic and remote. {{clear}} ==Spotting telescopes== {{main|Instruments/Telescopes/Spotting|Spotting telescopes}} [[Image:Yukon spotting scope.jpg|thumb|right|2050px|This is a 100 mm spotting scope with a coaxial 30 mm finderscope. Credit: .]] A '''spotting scope''' is a small portable [[telescope]] with added optics to present an [[erect image]], optimized for the observation of terrestrial objects. The light-gathering power and [angular] resolution of a spotting scope is determined by the diameter of the objective lens, typically between 50 and 80 mm. The larger the objective, the more massive and expensive the telescope. The optical assembly has a small refracting objective lens, an image erecting system that uses either image erecting relay lenses or prisms (porro prisms or roof prisms), and an eyepiece that is usually removable and interchangeable to give different magnifications. Other telescope designs are used such as Schmidt and Maksutov optical assemblies. They may have a ruggedised design, a mounting for attaching to a tripod, and an ergonomically designed and located knob for focus control. {{clear}} ==Observatories== {{main|Astronomy/Observatories|Observatories}} [[Image:Champaign-Urbana area IMG 1138.jpg|right|thumb|2050px|This equatorial room is at the University of Illinois Observatory. Credit: .]] Historically, observatories [are] as simple as [using or placing stably] an astronomical sextant (for measuring the distance between stars) or Stonehenge (which has some alignments on astronomical phenomena). Most optical telescopes are housed within a dome or similar structure, to protect the delicate instruments from the elements. Telescope domes have a slit or other opening in the roof that can be opened during observing, (contracted; show full)|volume=6 |issue=35 |page=85 }}</ref> Equatorial rooms tend to be large circular rooms to accommodate all the range of motion of a long telescope on an equatorial mount and are usually topped with a dome to keep out the weather. {{clear}} ==Lofting technology== {{main|Lofting technology}} Many devices for lofting technology have been developed to improve [[ Radiation astronomy/Keynote lecture|radiation astronomy]]. ==Balloons== {{main|Astronomy/Balloons|Balloons}} [[Image:BLAST on flightline kiruna 2005.jpeg|thumb|right|2050px|BLAST is hanging from the launch vehicle in [[w:Esrange|Esrange]] near [[w:Kiruna|Kiruna]], [[w:Sweden|Sweden]] before launch June 2005. Credit: [[commons:User:Mtruch|Mtruch]].]] [[Image:NASA Launches Telescope-Toting Balloon from-c3425de80831dab2a243aae9e0372fe7.jpeg|thumb|left|2050px|NASA's balloon-carried BLAST sub-millimeter telescope is hoisted into launch position on Dec. 25, 2012, at McMurdo Station in Antarctica. Credit: NASA/Wallops Flight Facility.]] The '''Balloon-borne Large Aperture Submillimeter Telescope''' ('''BLAST''') is a submillimeter [[w:telescope|telescope]] that hangs from a [[w:high altitude balloon|high altitude balloon]]. It has a 2 meter primary mirror that directs light into [[w:bolometer|bolometer]] arrays operating at 250, 350, and 500 µm. ... BLAST's primary science goals are:<ref>[http://blastexperiment.info/ BLAST Public Webpage]</ref> *Measure photometric [[w:redshift|redshift]]s, rest-frame [[w:Far infrared|FIR]] luminosities and star formation rates of high-redshift [[w:starburst galaxies|starburst galaxies]], thereby constraining the evolutionary history of those galaxies that produce the FIR/submillimeter background. *Measure cold pre-stellar sources associated with the earliest stages of [[w:star formation|star]] and [[w:planet formation|planet formation]]. *Make high-resolution maps of [[interstellar medium|diffuse galactic emission]] over a wide range of galactic latitudes. [[w:high-altitude balloon|High-altitude balloon]]s and aircraft ... can get above [much] of the atmosphere. The [[w:BLAST (telescope)|BLAST]] experiment and [[w:SOFIA|SOFIA]] are two examples, respectively, although SOFIA can also handle near infrared observations. At left above "NASA's balloon-carried BLAST sub-millimeter telescope is hoisted into launch position on Dec. 25, 2012, at McMurdo Station in Antarctica on a mission to peer into the cosmos."<ref name=SpaceDotCom>{{ cite book |author=SPACE.com |title=NASA Launches Telescope-Toting Balloon from Antarctica on Christmas |publisher=SPACE.com |location= |monthdate=December 25,⏎ |year= 2012 |url=http://news.yahoo.com/photos/nasa-launches-telescope-toting-balloon-antarctica-christmas-photo-164200244.html;_ylt=AoHsK.HbhPGTU8L1bT1.REEbANEA;_ylu=X3oDMTRramh0MW1uBG1pdANBcnRpY2xlIFJlbGF0ZWQgQ2Fyb3VzZWwEcGtnA2IyNDU3MjZmLTQ0NjQtMzJjMC05NGY2LTM5MGUxYTdkMjhkMgRwb3MDMQRzZWMDTWVkaWFBcnRpY2xlUmVsYXRlZENhcm91c2VsBHZlcgMwNzE3Yjc3MC00ZjdjLTExZTItYWQ1ZC05ODBjY2Q0Njg5OGQ-;_ylg=X3oDMTNhNjM2ZDhuBGludGwDdXMEbGFuZwNlbi11cwRwc3RhaWQDOWMzMDIyNDctMWM5NS0zMGYwLWIzNGItNDZjMjJkMjY0MmUyBHBzdGNhdANzY2llbmNlfHNwYWNlLWF(contracted; show full)d from further contracting into a star: turbulence in the dust, or the collapse-impeding effects of magnetic fields. On its new mission, BLAST should find out which process is to blame. ... [The 1800-kilogram] stratospheric telescope will observe selected [[star-forming region]]s in the constellations Vela and Lupus."<ref name=Schilling>{{ cite book |author=Govert Schilling |title=NASA Launches Telescope-Toting Balloon from Antarctica on Christmas |publisher=SPACE.com |location=McMurdo Station | monthdate=December 26,⏎ |year= 2012 |url=http://news.yahoo.com/nasa-launches-telescope-toting-balloon-antarctica-christmas-164200686.html |accessdate=2012-12-26 }}</ref> {{clear}} ==Aircraft assisted launches== {{main|Astronomy/Airborne/Launches|Aircraft assisted launches}} The '''Array of Low Energy X-ray Imaging Sensors''' ('''ALEXIS''') [[X-ray astronomy|X-ray]] telescopes feature curved mirrors whose multilayer coatings reflect and focus low-energy X-rays or extreme ultraviolet light the way [[w:optical telescope|optical telescope]]s focus visible light. ... The Launch was provided by the [[w:United States Air Force|United States Air Force]] Space Test Program on a [[w:Pegasus rocket|Pegasus]] Booster on April 25, 1993.<ref name=ALEXIA>{{ cite book |title=ALEXIS satellite marks fifth anniversary of launch |url=http://www.fas.org/spp/military/program/masint/98-062.html |accessdate=17 August 2011 |publisher=Los Alamos National Laboratory |date=23 April 1998 }}</ref> ==Hypotheses== {{main|Hypotheses}} # Ancients had and used telescopes.⏎ {{seealso|Control groups|Proof of concept|Proof of technology}} A control group for a radiation telescope would contain # an aperture, or an entry avenue into the instrument, # collimators, or lenses, to concentrate radiation, # moderators, to systematically reduce the incoming radiation so as to allow determination of incoming direction, # detectors, or sensors, to convert the incoming radiation into electrical impulses, # amplifiers, or processors, and # supports, to provide orientation and stability of all components. Proof of concept consists of a prototype instrument or device that makes a distant source appear nearer. ==See also== {{div col|colwidth=12em}} * [[w:List of telescope parts and construction|List of telescope parts]] * [[Radiation/Keynote lecture|Radiation]] * [[Radiation astronomy/Keynote lecture]] * [[Radiation detectors]] * [[Radiation satellites]] {{Div col end}} ==References== {{reflist|2}} (contracted; show full)* [http://www.springerlink.com/ SpringerLink] * [http://www.tandfonline.com/ Taylor & Francis Online] * [http://heasarc.gsfc.nasa.gov/cgi-bin/Tools/convcoord/convcoord.pl Universal coordinate converter] * [http://onlinelibrary.wiley.com/advanced/search Wiley Online Library Advanced Search] * [http://search.yahoo.com/web/advanced Yahoo Advanced Web Search] <!-- footer templates --> {{tlx|Astronomy resources}}{{ tlx|Principles of radiation astronomy}}{{tlx|Technology resources}}{{Sisterlinks|Radiation telescopes}} {{Sisterlinks|Telescopes}} <!-- categories --> [[Category:Astronomy learning projects/Lectures]] [[Category:Astronomy/Lectures]] [[Category:Instruments/Lectures]] [[Category:Materials sciences/Lectures]] [[Category:Radiation astronomy/Lectures]] [[Category:Resources last modified in Januaruly 2018]] [[Category:Technology/Lectures]] All content in the above text box is licensed under the Creative Commons Attribution-ShareAlike license Version 4 and was originally sourced from https://en.wikiversity.org/w/index.php?diff=prev&oldid=1901176.
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