An Etymological Dictionary of Astronomy and Astrophysics
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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.

→ Keplerian; → telescope.

Initial name given to → Vera C. Rubin Observatory.

→ large; → synoptic; → survey; → telescope.

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.

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)

A magnifying optical instrument for inspecting objects too small to be seen or too small to be seen distinctly and in detail by the unaided eye.

From Mod.L. microscopium "an instrument for viewing what is small," from Gk. → micro- + -skopion "means of viewing," from skopein "look at."

Rizbin, from riz→ micro- + bin "to see; seer" (present stem of didan; Mid.Pers. wyn-; O.Pers. vain- "to see;" Av. vaēn- "to see;" Skt. veda "I know;" Gk. oida "I know," idein "to see;" L. videre "to see;" PIE base *weid- "to know, to see").

A → NASA funded project to support and provide to the astronomical community a variety of astronomical data archives, with the primary focus on scientifically related data sets in the optical, ultraviolet, and near-infrared parts of the spectrum. MAST is a huge database that contains astronomical observations of stars, planets and galaxies from 16 separate NASA space science missions, including the Hubble Space Telescope. It is located at the Space Telescope Science Institute (STScI).

In honor of senator Barbara A. Mikulski for her active support for science, NASA, and the astrophysics community; → archive; → space; → telescope.

A small telescope dedicated entirely to → asterolseismology. MOST is the first space telescope entirely designed and constructed by Canada. It was launched into space in 2003. The satellite weighs only 54 kg and is equipped with an ultra high precision telescope that measures only 15 centimetres in diameter. Despite its tiny size, it is ten times more sensitive than the → Hubble Space Telescope in detecting the minuscule variations in a star's luminosity caused by vibrations that shake its surface. MOST completes one orbit around the Earth every 101 minutes by passing over each of Earth's poles.

MOST, short for Microvariability and Oscillations of STars telescope.

An → instrument used in → geophysics to determine the average → density of geological bodies by measuring the → attenuation produced by → rocks on the flux of → atmospheric muons. This density muon → radiography is or example used to study the physical conditions inside → volcanoes.

→ muon; → telescope.

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.

→ Newtonian; → telescope.

An optical instrument for viewing objects which are above the eye-level of the observer, or are placed so that direct vision is blocked.

→ peri-; + → -scope.

A telescope whose receiver is sensitive to → radio waves.

→ radio; → telescope.

A telescope in which the image is produced by reflection of light by a concave mirror.

Reflecting, verbal adj. of → reflect; → telescope.

A telescope in which an image is formed by the refraction of light through a lens or lens system.

→ refracting; → telescope.

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.

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.

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.

→ Schmidt telescope; → Cassegrain telescope.

A telescope designed so that heating effects produced by the Sun do not distort the images.

→ solar; → telescope.

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.

→ space; → telescope.

An optical instrument for forming and examining the spectrum of a light source. The instrument contains a narrow slit through which the light enters. The slit is placed at the focus of a positive lens called the collimator lens to form a beam of parallel rays. The beam of light falls on a dispersing element (prism, grating, or grism) which separates the light into its colors. This spectrum can be observed with an ocular (in the spectroscope) or recorded on a detector (in the spectrograph).

→ spectro-; → -scope.

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.