durbin-e Newton, teleskop-e ~
Fr.: télescope de Newton, ~ newtonien
A telescope with a concave paraboloidal objective mirror and a small plane mirror that reflects rays from the primary mirror laterally outside the tube where the image is viewed with an eyepiece.
râdio-teleskop (#), teleskop-e râdioyi (#)
Fr.: radio télescope
A telescope whose receiver is sensitive to → radio waves.
teleskop-e bâztâbi (#), durbin-e ~ (#)
Fr.: télescope réflecteur
A telescope in which the image is produced by reflection of light by a concave mirror.
teleskop-e šekasti (#), durbin-e ~ (#)
Fr.: lunette astronomique
A telescope in which an image is formed by the refraction of light through a lens or lens system.
teleskop-e Ritchey-Chrétien, durbin-e ~
Fr.: télescope Ritchey-Chrétien
A type of → Cassegrain telescope in which the → primary mirror is a → hyperboloid. It is designed to eliminate → coma and → spherical aberration, thus providing a relatively large field of view as compared to a more conventional configuration.
Named after the American astronomer George Ritchey (1864-1945) and the French optician Henri Chrétien (1879-1956); → telescope.
teleskop-e Schmidt, durbin-e ~ (#)
Fr.: télescope de Schmidt
A telescope with a spherical concave primary mirror in which the aberration produced by the spherical mirror is compensated for by a thin correcting lens placed at the opening of the telescope tube. Its very wide-field performance makes it suitable for surveys.
Named after Bernhard Woldemar Schmidt (1879-1935), a German optician of Estonian origin, who invented the telescope in 1930; → telescope.
teleskop-e Schmidt-Cassegrain, durbin-e ~ (#)
Fr.: télescope Schmidt-Cassegrain
A mixture of the → Cassegrain telescope with a very short → focal length and of a Schmidt design (due to the presence of the → corrective plate), used mainly in → amateur astronomy. The main advantage of this telescope is its compact design. However, Schmidt-Cassegrain telescopes produce fainter images with less contrast than other telescope designs with similar → aperture sizes. This is due to the comparatively large → secondary mirror required to reflect the light back the → eyepiece.
teleslop-e xoršidi, durbin-e ~
Fr.: télescope solaire
A telescope designed so that heating effects produced by the Sun do not distort the images.
teleskop-e fazâyi (#)
Fr.: télescope spatial
A telescope which is placed in an orbit around the → Earth and operates through commands from sent from the control center on Earth, such as → Hubble space telescope, → Herschel satellite, → Infrared Astronomical Satellite (IRAS), → Infrared Space Observatory (ISO), → International Ultraviolet Explorer (IUE), → Planck Satellaite , → Spitzer Space Telescope.
Spitzer Space Telescope
durbin-e fazâyi-ye Spitzer, teleskop-e ~ ~
Fr.: Télescope spatial Spitzer
An infrared telescope launched by NASA on 25 August 2003, the last in the series of Great Observatories. It was placed into a heliocentric orbit with a period of revolution that causes it to drift away from Earth at a rate of 0.1 → astronomical unit per year. Spitzer has a 85-cm primary mirror, made of beryllium and is equipped with three cryogenically-cooled science instruments: 1) IRAC (Infrared Array Camera), which operates simultaneously on four wavelengths (3.6, 4.5, 5.8, and 8 µm); 2) IRS (Infrared Spectrograph), with four sub-modules which operate at the wavelengths 5.3-14 µm (low resolution), 10-19.5 µm (high resolution), 14-40 µm (low resolution), and 19-37 µm (high resolution); and 3) MIPS (Multiband Imaging Photometer for Spitzer), three detector arrays in the → far infrared at 24, 70, and 160 µm. So far Spitzer has obtained precious data on all sorts of astronomical objects, thus contributing to all fields of astrophysics. It has also performed two sky surveys: GLIMPS, which covers 300° of the inner Milky Way galaxy, consisting of approximately 444,000 images taken at 4 separate wavelengths with the IRAC, and MIPSGAL a similar survey covering 278° of the Galactic disk at longer wavelengths.The planned nominal mission period was to be 2.5 years with a pre-launch expectation that the mission could extend to five or slightly more years until the onboard liquid helium supply was exhausted. This occurred on 15 May 2009. Without liquid helium to cool the telescope, most instruments are no longer usable. However, the two shortest wavelength modules of the IRAC camera are still operable and will continue to be used in the Spitzer Warm Mission.
Named in honor of Lyman Spitzer (1914-1997), an American theoretical physicist and astronomer best known for his research in star formation and plasma physics, who first suggested (1940s) placing telescopes in orbit to escape interference from the Earth's atmosphere; → space; → telescope.
durbin (#), teleskop (#)
An instrument used to collect and amplify light or other energy. → Refracting telescopes gather light by means of a lens, → reflecting telescopes by means of a mirror. → Radiotelescopes gather radio energy by using an antenna. Telescopes have also been built that can gather X rays, gamma rays, and other forms of energy. → grazing incidence telescope.
From It. telescopio (used by Galileo, 1611), and Mod.L. telescopium (used by Kepler, 1613), both from Gk. teleskopos "far-seeing," from → tele- "far" + -skopos "seeing," from skopein "to watch, look, behold;" → -scope.
gonbad-e durbin (#), ~ teleskop (#)
Fr.: coupole de télescope
A covering, usually hemispherical, that is rotatable about a central axis. There is a slit opening along one side wide enough to allow a telescope to be directed at any vertical angle up to 90°.
telescope pointing accuracy
rašmandi-ye âmâješ-e durbin, ~ ~ teleskvp
Fr.: précision du pointage de télescope
The accuracy with which a telescope can be pointed to a particular coordinate in the sky.
durbin-e borji, teleskop-e ~
Fr.: télescope vertical, tour solaire
durbin-e gozar-e nimruzâni, teleskop-e ~ ~
Fr.: lunette méridienne
Same as → transit instrument.
TRAnsiting Planets and PlanetesImals Small Telescope (TRAPPIST)
A Belgian facility devoted to the detection and characterization of → exoplanets and to the study of → comets (→ transiting planet) and other → small solar system bodies. It consists of two 60 cm robotic telescopes located at the → European Southern Observatory, → La Silla, in Chile and at Oukaïmden Observatory in Marroco.
Very Large Telescope (VLT)
tleskop-e besyâr bozorg
Fr.: Très Grand Télescope, VLT
An observing facility consisting of four 8.2 m telescopes, with the combined collecting area of a 16 m mirror, owned and operated by the European Southern Observatory at an altitude of 2635 m at the Paranal Observatory in Chile. The four reflecting unit telescopes are called Antu "Sun" in the language of Chile's indigenous Mapuche people, Kueyen "Moon," Melipal "Southern Cross," and Yepun "Venus." Each unit is equipped with several sophisticated instruments. The light of the individual telescopes can be combined using interferometric techniques to achieve superior resolution. → VLT Interferometer (VLTI). The wavelength range covered by the VLT is extremely wide, ranging from deep ultraviolet to mid-infrared.
Fr.: télescope Wolter
A → grazing incidence telescope designed to observe → X-ray emission from astronomical objects. Wolter telescopes use a combination of two elements, a parabolic mirror followed by a hyperbolic mirror and come in three different optical configurations. The design most commonly used by X-ray astronomers is the Type I since it has the simplest mechanical configuration. In addition, the Type I design offers the possibility of nesting several telescopes inside one another, thereby increasing the useful reflecting area. This is an extremely important attribute, since virtually all X-ray sources are weak, and maximizing the light-gathering power of a mirror system is critical. The → Chandra X-Ray Observatory is a Wolter Type I telescope that has four thick nested mirrors coated in iridium. The Japanese X-ray observatory Suzuki uses a conical approximation of the Wolter Type I design. Its mirrors are coated in gold, and they are far thinner than the ones used in Chandra. This allows for denser nesting, so there are 700 mirrors instead of four. The result is a much higher collecting efficiency at a reduced weight. For comparable apertures and grazing angles, the primary advantage of Type II over Type I is that higher magnifications are attainable. This is because the second reflection is off the outside of a surface, which allows longer focal lengths. However, since off-axis images suffer much more severely from blurring in Type II configurations, the Wolter Type II is useful only as a narrow-field imager or as the optic for a dispersive spectrometer. The Wolter Type III has never been employed for X-ray astronomy (NASA Imagine the Universe!).
Named after Hans Wolter (1911-1978), a German physicist who designed the optical configuration.
teleskop-e patow-e iks (#), durbin-e ~ ~
Fr.: télescope de rayons X
A telescope designed to focus X-rays from astronomical objects. X-ray telescopes function from orbital satellites because X-rays are absorbed by the Earth's atmosphere. These telescopes require special techniques since the conventional methods used in optical and radio telescopes are not adequate. → grazing-incidence telescope; → Bragg angle.
teleskop-e sarsu, dvrbin-e ~
Fr.: télescope zénithal
A → telescope that is mounted on a → vertical axis or moves only a small amount from the vertical. It is primarily used to determine positional measurement of stars moving near the → zenith. The advantage is that there is no → atmospheric refraction occurring at the zenith. If a star on one night passes through the center of eyepiece, one must observe it six month later, and see if the star has been offset by the center. A shift would mean a measure of parallax. See also: → zenithal well.