Difference between revisions 2240148 and 2241369 on enwikiversity

[[Image:Brorfelde Schmidt Telescope.jpg|thumb|right|250px|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|Keynote lectures/Astronomy}}
(contracted; show full)
"[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 ⏎
|author2=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|250px|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|translucent]].

"Bombardment by protostellar cosmic rays may make the rock precursors of [Calcium-aluminum-rich inclusions] CAIs and chondrules radioactive, producing radionuclides found in meteorites that are difficult to obtain with other mechanisms."<ref name=Lee>{{ cite journal
|author=Typhoon Lee, ⏎
|author2=Frank H. Shu and ⏎
|author3=Hsien Shang, ⏎
|author4=Alfred E. Glassgold and ⏎
|author5=K. E. Rehm
|title=Protostellar cosmic rays and extinct radioactivities in meteorites
|journal=The Astrophysical Journal
|month=October 20,
|year=1998
|volume=506
|issue=2
|pages=898-912
|url=http://iopscience.iop.org/0004-637X/506/2/898
|arxiv=
|bibcode=
|doi=10.1086/306284
|pmid=
|accessdate=2013-11-04 }}</ref>

"[[w:Ice core|Ice core]]s contain thin nitrate-rich layers that can be analyzed to reconstruct a history of past events before reliable observations; [this includes] data from Greenland ice cores<ref name=McCracken>{{ cite book
|url=http://www.stuartclark.com/files/thomas-qa.pdf
|title=How do you determine the effects of a solar flare that took place 150 years ago?
|publisher=Stuart Clarks Universe
|accessdate=May 23, 2012 }}</ref> and others. These show evidence that events of [the magnitude of the [[w:Solar storm of 1859|solar storm of 1859]]—as measured by high-energy proton radiation, not geomagnetic effect—occur approximately once per 500 years, with events at least one-fifth as large occurring several times per century.<ref name=McCracken01>{{ cite journal
|author=Kenneth G. McCracken, ⏎
|author2=G. A. M. Dreschhoff, ⏎
|author3=E. J. Zeller, ⏎
|author4=D. F. Smart, ⏎
|author5=M. A. Shea
|title=Solar cosmic ray events for the period 1561–1994 1. Identification in polar ice, 1561–1950
|journal=Journal of Geophysical Research
|volume=106
|issue=A10
|pages=21,585–21,598
|year=2001
|doi=10.1029/2000JA000237
(contracted; show full)
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 ⏎
|author2=N. Thomas
|author3=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
(contracted; show full)

"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
, ⏎
|author2=B. J. Teegarden, and ⏎
|author3=J. H. Trainor and ⏎
|author4=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
(contracted; show full)
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
, ⏎
|author2=G.K. Skinner, P. Jean, ⏎
|author3=P. Jean
|author4=J. Knödlseder, ⏎
|author5=P. von Ballmoos, R. Diehl, A. Strong, B. Cordier, S. Schanne, ⏎
|author6=R. Diehl
|author7=A. Strong
|author8=B. Cordier
|author9=S. Schanne
|author10=C. Winkler
|title=Positron astronomy with SPI/INTEGRAL
|journal=New Astronomy Reviews
|month=October
|year=2008
|volume=52
|issue=7-10
|pages=454-6
(contracted; show full)le Station|Amundsen-Scott South Pole Station]] in [[w:Antarctica|Antarctica]].[1] Similar to its predecessor, the [[w:Antarctic Muon And Neutrino Detector Array|Antarctic Muon And Neutrino Detector Array]] (AMANDA)<!-- which relied on analog data transmission except for one digital development string -->, IceCube contains thousands of spherical optical sensors called Digital Optical Modules (DOMs), each with a [[w:photomultiplier tube|photomultiplier tube]] (PMT)<ref name=Abbasi>{{cite journal

  |author=R. Abbasi ''et al.'' ⏎
|author2=''et al.''
|author3=(IceCube Collaboration)
 |year=2010
 |title=Calibration and Characterization of the IceCube Photomultiplier Tube
 |journal = Nuclear Instruments and Methods A
 | volume = 618| pages= 139–152
 | doi = 10.1016/j.nima.2010.03.102 
 |arxiv=1002.2442
 |bibcode=2010NIMPA.618..139A }}</ref>
and a single board data acquisition computer which sends digital data to the counting house on the surface above the array.<ref name=Abbasi09>{{ cite journal
  |author=R. Abbasi ''et al.'' ⏎
|author2=''et al.''
|author3=(IceCube Collaboration)
 |year=2009
 |title=The IceCube Data Acquisition System: Signal Capture, Digitization, and Timestamping
 |journal=Nuclear Instruments and Methods A
 |volume=601 |pages=294–316
 |doi=10.1016/j.nima.2009.01.001
 |bibcode = 2009NIMPA.601..294T
 |arxiv=0810.4930 }}</ref>  
(contracted; show full)
{{clear}}

==Refracting telescopes==
{{main|Instruments/Telescopes/Refracting|Refracting telescopes}}
[[Image:Kepschem.png|thumb|right|250px|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
, ⏎
|author2=JG Hirst
|date= 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 t(contracted; show full)
[[Image:Four-wire grid modulation collimator.jpeg|thumb|right|250px|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 ⏎
|author2=G. Garmire
|author3=M. Oda
|author4=G. Spada
|author5=B.V. Sreekantan, ⏎
|author6=P. Gorenstein and ⏎
|author7=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
(contracted; show full)d to be rotated about a single axis, at a constant rate, to follow the rotation of the night sky ([[w:diurnal motion|diurnal motion]]). Altazimuth mounts need to be rotated about both axes at variable rates, achieved via [[w:microprocessor|microprocessor]] based two-axis drive systems, to track equatorial motion. This imparts an uneven rotation to the field of view that also has to be corrected via a microprocessor based counter rotation system.<ref name=Mahra>{{ cite journal
  | author = H. S. Mahra
, ⏎
|author2=B. N. Karkera  
  | title = Field rotation with altazimuth mounting telescope
  | journal = Bulletin of the Astronomical Society of India 
  | volume = 13
  | issue = 
  | pages = 88
  | publisher = 
  | year = 1985 }}</ref> On smaller telescopes an [[w:equatorial platform|equatorial platform]]<ref>{{cite book
(contracted; show full)
|url=http://books.google.com/books?id=PexKTfPy3voC&pg=PA204&dq=%22called+a+clock+drive%22&hl=en&ei=etnITMabMIH_8Aa8v8StDw&sa=X&oi=book_result&ct=result&resnum=10&ved=0CFEQ6AEwCQ#v=onepage&q=%22called%20a%20clock%20drive%22&f=false
|title=Turn left at Orion: a hundred night sky objects to see in a small telescope ...
|author=Guy Consolmagno
, ⏎
|author2=Dan M. Davis, ⏎
|author3=Karen Kotash Sepp, ⏎
|author4=Anne Drogin, ⏎
|author5=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
(contracted; show full)
[[Image:FOCS-1.jpg|thumb|left|250px| 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
, ⏎
|author2=P. Kenneth Seidelmann
|location=Weinheim
|publisher=Wiley-VCH
|date=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 wa(contracted; show full)

The interplay between diffraction and aberration can be characterised by the [[w:point spread function|point spread function]] (PSF). The narrower the aperture of a lens the more likely the PSF is dominated by diffraction.

Two point sources are regarded as just resolved when the principal diffraction maximum of one image coincides with the first minimum of the other.<ref name=Born>{{ cite book
  | author = Max Born
 and ⏎
|author2=Emil Wolf
 | title = Principles of Optics
  | publisher = Cambridge University Press
  | date = October 1999
  | location = Cambridge
  | page = 461
  | isbn = 0-521-64222-1}}</ref>

(contracted; show full){{tlx|Radiation astronomy resources}}{{Principles of radiation astronomy}}{{tlx|Technology resources}}{{Sisterlinks|Radiation telescopes}}
{{Sisterlinks|Telescopes}}

<!-- categories -->
[[Category:Instruments/Lectures]]
[[Category:Materials sciences/Lectures]]
[[Category:Radiation astronomy/Lectures]]
[[Category:Technology/Lectures]]