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.
Fr.: chauffage par marées
The heating of the → interior of a → planet or → satellite due to the → friction caused by → tidal forces. For example, the huge tidal forces by → Jupiter heat its close satellite → Io, making it a seismically very active body.
arziz (#), qal'y (#)
A metallic chemical element; symbol Sn (L. stannum for → alloys containing → lead). → Atomic number 50; → atomic weight 118.69; → melting point 231.9681°C; → boiling point 2,270°C; → specific gravity 5.75 (gray), 7.3 (white). The element was known in prehistoric times.
M.E., O.E. tin; cf. M.Du., Du. tin, O.H.G. zin, Ger. Zinn, O.N. tin; related to Fr. étain?
Arziz "tin," from Mid.Pers. arziz "tin, lead,"
arus "white, bright;" Av. ərəzata- "silver,"
auruša- "white;" cf. Skt. arjuna- "white, shining,"
rajata- "silver;" Gk. argos "white," arguron "silver,"
L. argentum "silver," arguere
"to make clear," argmentum "argument;"
PIE *arg- "to shine, be white, bright, clear."
Transiting Exoplanet Survey Satellite (TESS)
mâhvâre-ye bardid-e borun-sayyârehâ-ye gozarandé
A → NASA space telescope devoted to the hunt for planets orbiting the brightest stars in the sky, launched on April 18, 2018. The mission is planned to monitor at least 200,000 stars for signs of → exoplanets using the → planetary transit method. TESS is equipped with four identical refractive → cameras with a combined → field of view (FOV) of 24 × 96 degrees. Each camera consists of a → CCD detector assembly, a → lens assembly, and a lens hood. The → entrance pupil diameter is 10.5 cm and the wavelength range 600 to 1,000 nm. The satellite is a follow-up of NASA's → Kepler spacecraft, but focuses on stars that are 30 to 100 times brighter than those Kepler examined.
Fr.: planète en transit
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.
Fr.: réseau par transmission
A diffraction grating that has grooves ruled onto a transparent material so that a beam of light passed through the grating is partly split into spectral orders.
Fr.: vision d'OVNI
The act or occasion of catching sight of a UFO.
→ UFO; sighting, from sight, M.E. from O.E. sihth; cf. Dan. sigte, Swed. sigt, Du. zicht, O.H.G. siht, Ger. Sicht, Gesicht, related to see.
Didâr "sight, vision," verbal noun from didan "to see" (Mid.Pers. ditan "to see, regard, catch sight of, contemplate, experience;" O.Pers. dī- "to see;" Av. dā(y)- "to see," didāti "sees;" cf. Skt. dhī- "to perceive, think, ponder; thought, reflection, meditation," dādhye; Gk. dedorka "have seen").
Fr.: vignettage, dégradé
The gradual reduction in energy through an optical system as the off-axis angle increases, resulting from limitations of the clear apertures of elements within the system.
From vignette "an unbordered picture, often a portrait, that shades off into the surrounding color at the edges;" "softening the edges of a picture in vignette style;" from Fr. vignette, O.Fr., diminutive of vigne "vineyard;" from L. vinea "vine, vineyard," from vinum "wine."
Labe-puš, literally "limb covering," from labé "limb," from lab "lip;" (Mid.Pers. lap; cf. L. labium; O.E. lippa; E. lip; Ger. Lefze) + puš present stem of pušidan "to cover; to put on" (Mid.Pers. pôšidan, pôš- "to cover; to wear;" cf. Mid.Pers. pôst; Mod.Pers. pust "skin, hide;" O.Pers. pavastā- "thin clay envelope used to protect unbaked clay tablets;" Skt. pavásta- "cover," Proto-Indo-Iranian *pauastā- "cloth").
Fr.: extinction visuelle
The → extinction in the visual range of the electromagnetic radiation.
Fr.: effet de couverture du vent
A process whereby dense winds of very luminous O type stars modify the temperature and internal structure of the underlying photosphere by scattering back a considerable part of the coming photospheric radiation. Not to be confused with → line blanketing .
Thus called because the wind acts like a blanket and heats the photosphere * by reflecting its radiation; → wind.
Fr.: monture anglaise à berceau
A form of → English mounting in which the → telescope is suspended inside an inclined fork, supported at both ends, and forming a → right ascension axis parallel to the Earth's → axis. The telescope pivots about the → declination axis inside two parallel forks.