Term Index (U)

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Term Index (U)

U: photometric filter for ultraviolet light
- dalton (Da,u): mass unit used on atomic scale
- distance modulus (u): apparent magnitude minus absolute magnitude
- large quasar group (LQG): structure consisting of a collection of quasars
U band:
- U: photometric filter for ultraviolet light
U filter:
- U: photometric filter for ultraviolet light
U-B:
- color index: a number that characterizes the color of an object
UAI:
- International Astronomical Union (IAU,UAI): association of professional astronomers
UBV photometric system: commonly-cited photometric system for describing stars' colors
UBVI photometric system:
- UBV photometric system: commonly-cited photometric system for describing stars' colors
UBVRI photometric system:
- UBV photometric system: commonly-cited photometric system for describing stars' colors
UC Santa Cruz:
- Other Worlds Laboratory (OWL): group researching planets and moons
UCLES:
- Anglo-Australian Telescope (AAT): 3.9m reflector telescope in Australia
UCSD Cosmic X-ray Experiment:
- OSO 7: 1970s observatory-satellite for viewing the Sun
UCSD Hard Solar X-ray Monitoring Instrument:
- OSO 7: 1970s observatory-satellite for viewing the Sun
UDF:
- Hubble Ultra-Deep Field (HUDF): extremely detailed HST image of a small region of space
UDFj:
- Hubble Ultra-Deep Field (HUDF): extremely detailed HST image of a small region of space
UDFy:
- Hubble Ultra-Deep Field (HUDF): extremely detailed HST image of a small region of space
UDS:
- UKIDSS: five-part infrared survey using UKIRT
UDXS:
- UKIDSS: five-part infrared survey using UKIRT
UFD:
- ultra-faint dwarf galaxy (UFD): recently discovered faint dwarf galaxies in the Local Group
UFT:
- Theory of Everything (TOE): single law explaining the four forces of nature
UFTI:
- United Kingdom Infrared Telescope (UKIRT): Mauna Kea 3.8 meter infrared telescope
UGC:
- Uppsala General Catalogue (UGC): 1979 catalog of galaxies visible from northern hemisphere
UGC 7654:
- M87: supergiant elliptical galaxy
UGCA:
- Uppsala General Catalogue (UGC): 1979 catalog of galaxies visible from northern hemisphere
UGCS:
- UKIDSS: five-part infrared survey using UKIRT
UGPS:
- UKIDSS: five-part infrared survey using UKIRT
UH Hilo Hoku Ke'a:
- Mauna Kea: Hawaiian mountain, the site of observatories
- Mauna Kea Observatories (MKO): observatories on Mauna Kea in Hawaii
UH88:
- Hawaii K-band Galaxy Survey: near-infrared survey of a selection of fields
- Mauna Kea: Hawaiian mountain, the site of observatories
- Mauna Kea Observatories (MKO): observatories on Mauna Kea in Hawaii
- Nearby Supernova Factory (NSNF,SNfactory): survey that scanned transient data for supernovae
UHE:
- VHE: 100 GeV or more
UHE cosmic rays:
- cosmic rays (CR): very-high-energy particles from beyond the solar system
UHECR:
- cosmic rays (CR): very-high-energy particles from beyond the solar system
UHEGR:
- ultra-high-energy gamma rays (UHEGR): energetic gamma rays with more than 100 TeV photon energy
Uhuru: 1970 satellite X-ray telescope
UIST:
- United Kingdom Infrared Telescope (UKIRT): Mauna Kea 3.8 meter infrared telescope
UIT:
- Ultraviolet Imaging Telescope (UIT): 1990s ultraviolet space telescope used on two Space Shuttle missions
UK Schmidt Southern Sky Survey:
- UK Schmidt Survey: photographic survey of the southern hemisphere sky
UK Schmidt Survey: photographic survey of the southern hemisphere sky
- Abell Catalog: galaxy cluster catalog assembled over 1950s-1980s
- APM Galaxy Survey (APMUKS): 1990s survey of galaxies in southern sky
- Arp-Madore Catalog of Southern Peculiar Galaxies (AM): 1970s-1980s catalog from the UK Schmidt Survey
- Digitized Sky Survey (DSS): digitization of Palomar and UK Schmidt plates
UK Schmidt Telescope (UKST): 1.2 meter telescope in Australia with wide field-of-view
- APM Galaxy Survey (APMUKS): 1990s survey of galaxies in southern sky
- field of view (FOV): angular measure of how much an optical instrument can view
- Large Bright QSO Survey (LBQS): 1980s quasar survey
- UK Schmidt Survey: photographic survey of the southern hemisphere sky
UKIDSS: five-part infrared survey using UKIRT
UKIRT:
- Hawaii K-band Galaxy Survey: near-infrared survey of a selection of fields
- Mauna Kea: Hawaiian mountain, the site of observatories
- Mauna Kea Observatories (MKO): observatories on Mauna Kea in Hawaii
- UKIDSS: five-part infrared survey using UKIRT
- United Kingdom Infrared Telescope (UKIRT): Mauna Kea 3.8 meter infrared telescope
- WFCAM Transit Survey (WTS): 2000s survey for exoplanet transits using UKIRT
UKIRT Infrared Deep Sky Survey:
- UKIDSS: five-part infrared survey using UKIRT
UKST:
- Abell Catalog: galaxy cluster catalog assembled over 1950s-1980s
- APM Galaxy Survey (APMUKS): 1990s survey of galaxies in southern sky
- Catalog of Galaxies and Clusters of Galaxies (CGCG): list of galaxies/clusters assembled in 1960s
- field of view (FOV): angular measure of how much an optical instrument can view
- Large Bright QSO Survey (LBQS): 1980s quasar survey
- UK Schmidt Survey: photographic survey of the southern hemisphere sky
- UK Schmidt Telescope (UKST): 1.2 meter telescope in Australia with wide field-of-view
ULAS:
- UKIDSS: five-part infrared survey using UKIRT
ULEIS:
- Advanced Composition Explorer (ACE): satellite collecting solar wind and cosmic rays
ULF:
- ultra low frequency (ULF): electromagnetic radiation, frequency 300Hz to 3kHz
ULIRG:
- ultraluminous infrared galaxy (ULIRG): a galaxy emitting a more far infrared than an LIRG
Ultima Thule:
- New Horizons (NF1): explorer spaceship sent to Pluto
Ultimate Spitzer Phase Curve Survey (USPCS): investigation of exoplanet atmospheres
ultra high energy:
- VHE: 100 GeV or more
ultra low frequency (ULF): electromagnetic radiation, frequency 300Hz to 3kHz
ultra-compact dwarf galaxy:
- dwarf galaxy: small galaxy with a few billion stars
ultra-cool dwarf:
- ultracool dwarf: star or brown dwarf cooler than M7 class
ultra-faint dwarf galaxy (UFD): recently discovered faint dwarf galaxies in the Local Group
ultra-high energy cosmic rays:
- cosmic rays (CR): very-high-energy particles from beyond the solar system
ultra-high-energy gamma rays (UHEGR): energetic gamma rays with more than 100 TeV photon energy
ultracool dwarf: star or brown dwarf cooler than M7 class
- SPECULOOS: search for Earth-like exoplanets orbiting nearby dim stars
ultraluminous infrared galaxy (ULIRG): a galaxy emitting a more far infrared than an LIRG
ultraluminous X-ray source (ULX): X-ray source with luminosity between a star and an AGN
ultrarelativistic:
- relativistic speed: a good fraction of the speed of light
ultrarelativistic speed:
- relativistic speed: a good fraction of the speed of light
ultraviolet (UV): electromagnetic radiation, wavelength 10-400 nm
- Berkeley Extreme and Far-UV Spectrometer (BEFS): 1990s UV spectrometer used on two shuttle missions
- COLD GASS: survey of CO in nearby large galaxies
- European Southern Observatory Very Large Telescope (ESO VLT,VLT): four 8.2-meter optical telescopes in Chile that can act together
- extreme ultraviolet (EUV,XUV): electromagnetic radiation in the range of 10nm-124nm
- Extreme Ultraviolet Explorer (EUVE): 1990s ultraviolet space telescope
- Far Ultraviolet Spectroscopic Explorer (FUSE): early 2000s space telescope for short-wavelength ultraviolet
- Galaxy Evolution Explorer (GALEX): observatory-satellite with 50cm ultraviolet telescope
- HEASARC: archive of NASA data on high energy astronomy
- High Definition Space Telescope (HDST): proposed 12m space telescope
- Hopkins Ultraviolet Telescope (HUT): 1990s ultraviolet space telescope used on two shuttle missions
- International Ultraviolet Explorer (IUE): 1980s ultraviolet space telescope
- Interstellar Medium Absorption Profile Spectrograph (IMAPS): 1980s/1990s UV spectrometer
- Kiso Survey of Ultraviolet Excess Galaxies (KUG): 1980 Japanese survey
- Large Binocular Telescope (LBT): dual 8.4 meter telescope in Arizona
- LUVOIR: plan for a space-based 10 meter telescope
- Lyman-Werner photon: ultraviolet photon with proper energy to excite molecular hydrogen
- Markarian galaxy (Mkn): list of galaxies with excess ultraviolet light
- MUSCLES: HST UV survey of some M Dwarfs that host exoplanets
- Palomar-Green Survey (PG): list of quasars with excess ultraviolet light
- Solar and Heliospheric Observatory (SOHO): satellite observing the Sun
- Solar Maximum Mission (SMM): 1980s satellite to study the Sun during solar maximum
- Swift: satellite for studying gamma-ray bursts
- TRACE: former solar observing satellite
- Tubingen Ultraviolet Echelle Spectrometer (TUES): 1990s UV spectrometer used on two Space Shuttle missions
- U: photometric filter for ultraviolet light
- Ultraviolet Hubble Ultra-deep Field (UVUDF): ultraviolet data covering the Hubble Ultra Deep Field region of the sky
- Ultraviolet Imaging Telescope (UIT): 1990s ultraviolet space telescope used on two Space Shuttle missions
- UVOIR: a spectral "band name" covering UV, visible light, and IR
- VLT Survey Telescope (VST): survey telescope located at the VLT site
- Wisconsin Ultraviolet Photo-polarimeter Experiment (WUPPE): 1990s ultraviolet space telescope used on two shuttle missions
- XEUV: electromagnetic radiation in the range of .15nm-400nm
ultraviolet catastrophe:
- Rayleigh-Jeans law: yields approximation of black body curve
Ultraviolet Coverage of the Panchromatic Hubble Ultra Deep Field:
- Ultraviolet Hubble Ultra-deep Field (UVUDF): ultraviolet data covering the Hubble Ultra Deep Field region of the sky
Ultraviolet Hubble Ultra-deep Field (UVUDF): ultraviolet data covering the Hubble Ultra Deep Field region of the sky
Ultraviolet Imaging Telescope (UIT): 1990s ultraviolet space telescope used on two Space Shuttle missions
ultraviolet light:
- ultraviolet (UV): electromagnetic radiation, wavelength 10-400 nm
UltraVISTA: near infrared survey using VISTA telescope
- VISTA: 4.1 meter telescope in Paranal Observatory in Chile
ULX:
- ultraluminous X-ray source (ULX): X-ray source with luminosity between a star and an AGN
UMa II dSph:
- Ursa Major II Dwarf: dwarf spheroidal galaxy in the Local Group
Umbriel:
- moon: a planet's natural satellite, such as Earth's
- Uranus: second outer-most solar system planet
unbound GMC:
- giant molecular cloud (GMC): interstellar gas cloud with molecules, thousands of solar masses
UNH Solar Gamma-ray Monitor:
- OSO 7: 1970s observatory-satellite for viewing the Sun
unified atomic mass unit:
- dalton (Da,u): mass unit used on atomic scale
unified field theory:
- Theory of Everything (TOE): single law explaining the four forces of nature
uniform theory of diffraction:
- diffraction: effect of an obstacle on a wave
unit:
- angstrom (Å): unit of length 10^-10 meters
- arcsecond (arcsec,sec): a 3600th of an angular degree
- astronomical unit (AU): about 93 million miles
- atm: unit of pressure
- dalton (Da,u): mass unit used on atomic scale
- dex: a number or factor's log base 10
- erg: CGS unit of energy
- foe: unit of energy on the order of a supernova's output
- Gal: gravimetry unit of the effect of a planet's gravity
- gauss (G,Gs): measurement of magnetic field β
- gigayear (Gy,Gyr): a billion years
- jansky (Jy): unit of measurement of spectral flux density
- joule: SI unit of energy
- light-year (ly): distance that light travels in a year
- parsec (pc): about 3.26 light-years
- solar mass (M_Sun,Msun): mass unit representing the mass of the Sun
- solar neutrino unit (SNU): unit for the detection rate of neutrino detectors
- tesla (T): unit of magnetic flux density
- watt (W): SI unit of power
United Kingdom Infrared Telescope (UKIRT): Mauna Kea 3.8 meter infrared telescope
United States Naval Observatory:
- NOMAD: astrometric star catalog
- USNO: observatory obtaining astronomical data for Naval use
universal time:
- time standard: method of designating points in time and quantifying time periods
University of Bonn:
- Max Planck Institute for Radio Astronomy (MPIR): Bonn research institute
University of Cologne:
- Max Planck Institute for Radio Astronomy (MPIR): Bonn research institute
University of Hawaii:
- IRTF: Mauna Kea 3-meter infrared telescope
University of Hawaii Institute for Astronomy:
- Mauna Kea Observatories (MKO): observatories on Mauna Kea in Hawaii
University of Heidelberg:
- Max Planck Institute for Astronomy (MPIA): Heidelberg research institute
University of Texas Radio Astronomy Observatory:
- Texas Survey of Radio Sources at 365 MHz (TXS): 1970s/1970s radio survey made with the Texas Interferometer
University of Tokyo Atacama Observatory (TAO): observatory for a 6.5m infrared telescope under construction
University of Toronto:
- Canadian Institute for Theoretical Astrophysics (CITA,ICAT): national research organization at University of Toronto
University of Tubingen:
- Tubingen Ultraviolet Echelle Spectrometer (TUES): 1990s UV spectrometer used on two Space Shuttle missions
Uniview: planetarium software
unnormalized PDF:
- probability density function (PDF): shows probability of taking a particular value from a continuous range
unstable isotope:
- isotope: subclass of an element with a specific number of nucleons
up quark:
- particle: very small thing
- standard model: model of elementary particles including quarks
Upper-Scorpius OB Association:
- CTIO Upper-Scorpius OB Association Survey (UScoCTIO): survey of low-mass stars and brown dwarfs
Uppsala General Catalogue (UGC): 1979 catalog of galaxies visible from northern hemisphere
Uppsala General Catalogue of Galaxies:
- Uppsala General Catalogue (UGC): 1979 catalog of galaxies visible from northern hemisphere
Uranus: second outer-most solar system planet
- giant planet: planet of more than 10 Earth masses
- ice giant: planet more massive than gas planets and less than rocky planets
- ring system: disk or set of rings orbiting a planet
- shepherd moon: small moon at outer edge of a ring
- Voyager: space probes to observe planets and the edge of the solar system
Urca process: neutrino-emitting process
Ursa Major Filament:
- galaxy filament: thread-like formations of galaxies, 50 to 80 megaparsecs
Ursa Major II Dwarf: dwarf spheroidal galaxy in the Local Group
US Air Force:
- LINEAR: survey of near-Earth objects
US Navy:
- USNO: observatory obtaining astronomical data for Naval use
USA:
- NASA: includes space-based astronomy research
- National Radio Astronomy Observatory (NRAO): US-operated radio astronomy organization
- NSF AST: US government astronomical research funding division
- Space Telescope Science Institute (STScI): science operator of space telescopes
UScoCTIO:
- CTIO Upper-Scorpius OB Association Survey (UScoCTIO): survey of low-mass stars and brown dwarfs
USNO: observatory obtaining astronomical data for Naval use
- NOMAD: astrometric star catalog
USNO-A:
- NOMAD: astrometric star catalog
USNO-B:
- NOMAD: astrometric star catalog
USO/RS:
- Mars Global Surveyor (MGS): Mars probe launched by NASA in 1996
USPCS:
- Ultimate Spitzer Phase Curve Survey (USPCS): investigation of exoplanet atmospheres
USS Sources: catalog of sources with steep spectral index
UT:
- time standard: method of designating points in time and quantifying time periods
UT1 Telescope:
- European Southern Observatory Very Large Telescope (ESO VLT,VLT): four 8.2-meter optical telescopes in Chile that can act together
UT2 Telescope:
- European Southern Observatory Very Large Telescope (ESO VLT,VLT): four 8.2-meter optical telescopes in Chile that can act together
UT3 Telescope:
- European Southern Observatory Very Large Telescope (ESO VLT,VLT): four 8.2-meter optical telescopes in Chile that can act together
UT4 Telescope:
- European Southern Observatory Very Large Telescope (ESO VLT,VLT): four 8.2-meter optical telescopes in Chile that can act together
UTC:
- time standard: method of designating points in time and quantifying time periods
UTRAO:
- Texas Survey of Radio Sources at 365 MHz (TXS): 1970s/1970s radio survey made with the Texas Interferometer
UUDS:
- UKIDSS: five-part infrared survey using UKIRT
UV:
- ultraviolet (UV): electromagnetic radiation, wavelength 10-400 nm
UV star formation rate:
- star formation rate (SFR): rate at which material such as gas is turned into stars
UV, optical, and infrared:
- UVOIR: a spectral "band name" covering UV, visible light, and IR
UVA:
- ultraviolet (UV): electromagnetic radiation, wavelength 10-400 nm
UVB:
- ultraviolet (UV): electromagnetic radiation, wavelength 10-400 nm
uvby photometric system:
- Strömgren photometric system: four-color photometric system devised in 1950s
uvby system:
- Strömgren photometric system: four-color photometric system devised in 1950s
UVC:
- ultraviolet (UV): electromagnetic radiation, wavelength 10-400 nm
UVCS:
- Solar and Heliospheric Observatory (SOHO): satellite observing the Sun
UVES:
- European Southern Observatory Very Large Telescope (ESO VLT,VLT): four 8.2-meter optical telescopes in Chile that can act together
- integral field spectrograph: spectrograph that captures images
- integral field unit (IFU): instrument to allow a spectrograph to capture data over a 2d field
UVIS:
- Cassini: explorer spaceship sent to Saturn
UVOIR: a spectral "band name" covering UV, visible light, and IR
UVOT:
- Swift: satellite for studying gamma-ray bursts
UVOTSSC1:
- Swift: satellite for studying gamma-ray bursts
UVS:
- Europa Clipper: planned Europa space probe
- JUICE: mission to Jupiter in development
- Juno: mission to Jupiter
- Voyager: space probes to observe planets and the edge of the solar system
UVUDF:
- Ultraviolet Hubble Ultra-deep Field (UVUDF): ultraviolet data covering the Hubble Ultra Deep Field region of the sky

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