align a telescope
âxatidan-e durbin, ~ teleskop
Fr.: aligner un télescope
Setting the axis of a telescope parallel to prime directions. In equatorial mounting, they are made parallel with the Earth's axis of rotation and the equator respectively. → collimation.
Allen Telescope Array (ATA)
Ârast-e Teleskophâ-ye Allen
Fr.: Réseau de Télescopes Allen
A "Large Number of Small Dishes" (LNSD) array designed to be sensitive for → commensal surveys of conventional → radio astronomy projects and → SETI targets at centimeter wavelengths. The ATA will consist of 350 6m-diameter → dishes when completed, which will provide an outstanding survey speed and sensitivity. In addition, the many → antennas and → baseline pairs provide a rich → sampling of the → interferometer → uv plane, so that a single pointing snapshot of the array of 350 antennas yields an image in a single field with about 15,000 independent → pixels. Other important features of the ATA include continuous frequency coverage over 0.5 GHz to 10 GHz and four simultaneously available 600-MHz bands at the → back-end which can be tuned to different frequencies in the overall band. The ATA is a joint project of the Radio Astronomy Laboratory of the University of California, Berkeley, and the SETI Institute in Mountain View, CA. The ATA is now complete to 42 antennas. Highlights of the system are the frequency agility, the low background and → side lobes of the antennas, the wideband feed and input receiver, the analog fiber optical system, the large spatial dynamic range, the back-end processing systems and the overall low cost (see, e.g., Backer et al., 2009, arXiv:0908.1175.pdf).
Named after Paul G. Allen (1953-2018), an American business magnate, computer programmer, researcher, investor, and philanthropist. A donation of $11.5 million by his foundation in 2004 contributed to the development of the project.
automatic photometric telescope
durbin-e šidsanjik-e xodkâr, teleskop-e ~ ~
Fr.: télescope photométrique automatique
A telescope developed to perform photometric observations automatically.
durbin-e bâlon-bord, teleskop-e ~
Fr.: télescope porté par ballon
A remotely guided or automatic telescope carried to high altitudes by a balloon.
→ balloon astronomy; borne "a past participle of bear," from O.E. beran "bear, bring, wear," from P.Gmc. *beranan (O.H.G. beran, Goth. bairan "to carry"), from PIE root *bher-; "to carry;" compare with Av./O.Pers. bar- "to bear, carry," bareθre "to bear (infinitive)," bareθri "a female that bears (children), a mother," Mod.Pers. bordan "to carry," Skt. bharati "he carries," Gk. pherein, L. fero "to carry." → telescope.
Canada-France-Hawaii Telescope (CFHT)
Fr.: télescope Canada-France-Hawaii
A 3.6 m optical/infrared telescope jointly owned and operated by the Canadian National Research Council (NRC), the French Centre National de la Recherche Scientifique (CNRS), and the University of Hawaii. It became operational in 1979. The observatory is located atop the summit of Mauna Kea, a 4200 m, dormant volcano located on the island of Hawaii. The Observatory headquarters is located in Waimea (also known as Kamuela by the US Postal Service). Situated at the low latitude of Hawaii (+19° 45'), there is a fairly large sky overlapping with that of the → European Southern Observatory (ESO) → La Silla observatory (δ = -29° 15'). The point where an object is seen at the same → zenith distance from La Silla and from Mauna Kea, when it crosses the meridian, is δ =-5°. Taking into consideration also the difference in elevation between the observatories, the → declination at which one has equal air mass is moved down to δ =-18°. The extreme limit of observing from Mauna Kea is -60° (10° above horizon) but all programs below -20° are most efficiently carried out from ESO.
Canada, from the St. Lawrence Iroquoian word kanata, meaning "village" or "settlement;" France, from the L. Francia "country of the Franks;" Hawaii, named for Hawai'iloa, a legendary figure from Hawaiian mytholgy; → telescope.
durbin Cassegrain, teleskop-e ~ (#)
Fr.: Télecope Cassegrain
A reflecting telescope whose primary mirror has a hole bored through the center to allow the reflected light from the convex secondary mirror be focused beyond the back end of the tube.
Cassegrain, named after the French priest and school teacher Laurent Cassegrain (1629-1693), who invented this system in 1672; → telescope.
Event Horizon Telescope (EHT)
Teleskop-e Ofoq-e Ruydâd
Fr.: Télescope de l'horizon des évènements
An international collaboration using a → very-long-baseline interferometry (VLBI) array comprising millimeter- and → submillimeter- wavelength telescopes separated by distances comparable to the diameter of the Earth. At a nominal operating wavelength of ~1.3 mm, the EHT → angular resolution (λ/D) is ~25 μas (→ micro- → arcseconds), which is sufficient to resolve nearby → supermassive black hole candidates on spatial and temporal scales that correspond to their → event horizons. EHT observations toward the elliptical → galaxy M87 succeeded in obtaining the first ever image of its supermassive black hole (EHT Collaboration, 2019, ApJL 875, L1-L6). The telescopes contributing to this result were ALMA, APEX, the IRAM 30-m telescope, the James Clerk Maxwell Telescope, the Large Millimeter Telescope Alfonso Serrano, the Submillimeter Array, the Submillimeter Telescope, and the South Pole Telescope. Petabytes of raw data from the telescopes were combined by highly specialized supercomputers hosted by the Max Planck Institute for Radio Astronomy and MIT Haystack Observatory. The construction of the EHT and the M87 black hole observation result from decades of observational, technical, and theoretical work in close collaboration by researchers from around the world. Thirteen partner institutions worked together to create the EHT, using both pre-existing infrastructure and support from a variety of agencies. Key funding was provided by the US National Science Foundation (NSF), the EU's European Research Council (ERC), and funding agencies in East Asia.
Fermi Gamma-ray Space Telescope
Durbin-e fazâyi-ye partowhâ-ye gâmâ Fermi
Fr.: Télescope spatial à rayons gamma Fermi
A space observatory, formerly named GLAST, devoted to the study of → gamma rays emitted from astrophysical objects. Developed by NASA in collaboration with the U.S. Department of Energy, along with important contributions from academic institutions and partners in France, Germany, Italy, Japan, Sweden, and the United States, Fermi was launched on June 11, 2008. The main instrument, the Large Area Telescope (LAT), is an imaging → camera covering the energy range from about 20 → MeV to more than 300 → GeV. Such gamma rays are emitted only in the most extreme conditions, by particles moving very nearly at the → speed of light. The LAT's → field of view covers about 20% of the sky at any time, and it scans continuously, covering the whole sky every three hours. Another instrument, the Gamma-ray Burst Monitor (GBM) has a field of view several times larger than the LAT and provides → spectral coverage of → gamma-ray burst that extends from the lower limit of the LAT down to 10 → keV.
Five-hundred-meter Aperture Spherical radio Telescope (FAST)
The 500 m diameter → radio telescope which is the largest → single-dish antenna in the world. It is an Arecibo type telescope nestled within a natural basin in China's remote and mountainous Dawodang, Kedu Town, in southeastern China's Guizhou Province. The → reflector consists of 4,450 triangular panels, each with a side length of 11 m. More than 2,000 → actuators are used, according to the feedback from the measuring system, to deform the whole reflector surface and directly correct for → spherical aberration. Several detectors are used to cover a frequency range of 70 MHz to 3 GHz.
teleskop bâ fotâd-e barmažandé
Fr.: télescope à incidence rasante
A telescope design used for focusing → extreme ultraviolet, → X-rays, and → gamma rays by means of → grazing incidence. Such short wavelengths do not reflect in the same manner as at the large incidence angles employed in optical and radio telescopes. Instead, they are mostly absorbed. To bring X-rays to a → focus, one has to use a different approach from → Cassegrain or other typical → reflecting telescopes. In a grazing-incidence telescope, incoming light is almost → parallel to the → mirror surface and strikes the mirror → surface at a very → shallow angle. Much like skipping a stone on the water by throwing it at a low angle to the surface, X-rays may be → deflected by mirrors arranged at low incidence angles to the incoming energy. Several designs of grazing-incidence mirrors have been used in various → X-ray telescopes, including → plane mirrors or combinations of → parabolic and → hyperbolic surfaces. To increase the collecting area a number of mirror elements are often nested inside one another. For example, the → Chandra X-ray Observatory uses two sets of four nested grazing-incidence mirrors to bring X-ray photons to focus onto two → detector instruments. → Bragg's law; → X-ray astronomy.
durbin-e Gregori, teleskop-e ~ (#)
Fr.: télescope de Gregory
A reflecting telescope in which the light rays are reflected from the primary mirror to a concave secondary mirror, from which the light is reflected back to the primary mirror and through the central hole behind the primary mirror. Compare with the → Cassegrain telescope, in which the secondary mirror is convex.
Named after the Scottish mathematician and astronomer James Gregory (1638-1675), who devised the telescope, but did not succeed in constructing it; → telescope.
Fr.: lunette de guidage
A telescope which is attached to a second telescope being used for photographic purposes. The guiding telescope, mounted parallel to the optical axis of the main telescope, is used by the observer to keep the image of a celestial body motionless on a photographic plate.
teleskop-e Herschel, durbin-e ~
Fr.: télescope de Herschel
A → reflecting telescope in which the → primary mirror is tilted so that light is focused near one side of the open end of the tube. The → eyepiece then picks up this light directly, avoiding light loss from reflection by a → secondary mirror. The drawback is → astigmatism, unless the → focal ratio is large. Herschel used this design in his giant 48-inch instrument.
Hubble Space Telescope (HST)
durbin-e fazâyi-ye Hubble, teleskop-e ~ ~ (#)
Fr.: télescope spatial de Hubble
A telescope of 2.4 m in diameter, a joint NASA and ESA project, launched in 1990 into a low-Earth orbit 600 km above the ground. It was equipped with a collection of several science instruments that worked across the entire optical spectrum (from infrared, through the visible, to ultraviolet light). During its lifetime Hubble has become one of the most important science projects ever.
durbin-e forusorx (#), teleskop-e ~ (#)
Fr.: télescope infrarouge
A telescope capable of observing → infrared radiation from astronomical objects.
James Webb Space Telescope (JWST)
durbin-e fazâyi-ye James Webb, teleskop ~ ~ ~
Fr.: Télescope spatial James Webb
A large, infrared space telescope with a mirror 6.55 m in diameter, scheduled for launch in 2018. JWST's instruments will work primarily in the infrared range of the electromagnetic spectrum, with some capability in the visible range (0.6 to 28 μm). The scheduled instruments are Near IR Camera (NIRCam, field of 2.2 x 4.4 arcmin, wavelength range 0.6-5 μm), Near IR Spectrograph (NIRSpec, 3.5 x 3.5 arcmin, 0.6-5 μm, resolving powers of ~ 100, ~1000, and ~3000), Mid IR Instrument (MIRI, 1.4 x 1.9 arcmin, 5-27 μm, R ~ 3000), and Fine Guidance Sensor (FGS, 2.3 x 2.3 arcmin, 0.6-5 μm, R ~ 100). The successor to the → Hubble Space Telescope will be placed in an orbit about 1.5 million km from the Earth, at the → Lagrangian point L2. The JWST project is a → NASA-led international collaboration with the → European Space Agency and the Canadian Space Agency. The scientific goals of JWST can be grouped under four broad topics: first light after the Big Bang; galaxy formation; birth of stars and protoplanetary systems; and planetary systems and the origins of life.
Named in honor of James E. Webb (1906-1992), who headed NASA from 1961 to 1968, overseeing all the manned launches in the Mercury through Gemini programs, until before the first manned Apollo flight; → space; → telescope.
durbin-e Kepler, teleskop-e ~ (#)
Fr.: télescope de Kepler
A → refracting telescope which has simple → convex lenses for both → objective and → eyepiece. It suffers from → chromatic aberration, which can be reduced by increasing the → focal ratio. It was first devised by Kepler in 1615.
Large Synoptic Survey Telescope (LSST)
teleskop-e bozorg-e hanvini barâye bardid
Fr.: Grand Télescope d'étude synoptique
Initial name given to → Vera C. Rubin Observatory.
durbin-e Maksutof, teleskop-e ~ (#)
Fr.: télescope de Maksutov
A → reflecting telescope incorporating a deeply curved → meniscus, → lens, which corrects the → optical aberrations of the spherical → primary mirror to give high-quality → images over a wide → field of view.
Named for the Russian optical specialist Dmitri Maksutov (1896-1964), who developed the design; → telescope.
Fr.: télescope de Mercator
A 1.2 m semi-robotic telescope located at the Roque de los Muchachos Observatory on La Palma Island (Canary Islands, Spain). It is operated by the staff of the Institute of Astronomy, University of Leuven (Belgium). The telescope uses two modern instruments HERMES: a → high-resolution optical → spectrograph, and MAIA, a three-armed camera equipped with large → charge-coupled device (CCD)s and optimized for more specific rapid variability studies. The main science drivers of the research performed on the basis of Mercator data are related to a wide range of variable phenomena with a clear focus on stellar astrophysics, in particular the stellar internal structure by means of → asteroseismology.
Named after the Flemish cartographer Gerardus Mercator (1512-1594), who studied and taught at the University of Leuven before moving to Duisburg (Germany)