Term Index (X)

 XA  XB  XC  XD  XE  XF  XG  XI  XL  XM  XN  XO  XQ  XR  XS  XT  XU  XV  XZ

• X: see NIRSpec
• X: see X-ray source
• X: see filter designator
• X: see mass fraction
  • hydrogen: most prominent element, atomic number 1
  • metallicity: metal fraction of an object
• X-IFU: see ATHENA
• X-ray: electromagnetic radiation, wavelength 0.01 to 10 nanometers
  • A Broadband Imaging X-ray All-sky Survey: failed 1999 space mission
  • ACIS: imaging spectrometer on Chandra X-ray telescope
  • AGN corona: plasma surrounding or near an AGN
  • ALEXIS: 1990s soft X-ray transient monitor
  • anomalous X-ray pulsar: X-ray pulsars with no high-mass companion
  • Arcus: X-ray space telescope plan aiming for 2031 launch
  • Ariel 5: 1970s X-ray space telescope
  • ASCA: 1990s Japanese space X-ray telescope
  • ATHENA: planned ESA X-ray space telescope
  • AXIS: concept for space X-ray observatory
  • BeppoSAX: Italian-Dutch space X-ray telescope
  • Broad Band X-Ray Telescope: 1990s Astro-1 Space Shuttle X-ray telescope
  • Chandra Deep Field North: X-ray deep survey encompassing HDF region
  • Chandra Deep Field South: X-ray deep survey encompassing HDF-South region
  • Chandra X-ray Observatory: space X-ray telescope
  • Compton reflection: recognizable emission due to a gas or plasma's Compton scattering
  • cooling flow: inward flow of ICM within galaxy clusters
  • cosmic X-ray background: X-ray radiation coming from outside the Milky Way
  • COUP: survey of X-ray sources in the Orion Nebula
  • Einstein Probe: Chinese X-ray space observatory
  • electromagnetic spectrum: spectrum of EMR
  • eROSITA: Russian/German space X-ray telescope launched in 2019
  • EXOSAT: 1980s European space X-ray telescope
  • eXTP: plan for a space X-ray telescope
  • Ginga: 1980s Japanese space X-ray telescope
  • GRANAT: observatory-satellite for detecting gamma rays and X-rays
  • Group Evolution Multiwavelength Study: survey of galaxy groups
  • GRS 1915+105: stellar-mass black hole microquasar
  • HEAO-1: 1977 X-ray observatory space mission
  • HEAO-2: 1978 X-ray observatory space mission
  • HEASARC: NASA archive of data on high energy astronomy
  • High Energy Transient Explorer: 2000s space multi-band GRB observatory
  • high-energy astrophysics: astronomy and physics of X-rays and gamma rays
  • Hitomi: 2016 Japanese space X-ray telescope
  • HXMT: space X-ray observatory launched in 2017
  • ionizing radiation: radiation with photon energy sufficient to ionize
  • IXPE: space observatory with X-ray polarimeters
  • Kepler-Swift Active Galaxies and Stars Survey: X-ray/UV survey of objects within the Kepler field
  • Lynx: concept for space X-ray observatory
  • MAXI: Japanese X-ray camera on the International Space Station
  • microcalorimeter: instrument to measure small amounts of heat
  • MIT X-ray Burst Source Catalog: 1970s catalog of X-ray bursters
  • NICER: space X-ray mission specifically to view neutron stars
  • NuSTAR: space telescope for high-energy X-rays
  • obscured fraction-luminosity relation: relation between AGN luminosity and surrounding dust IR emission
  • Puppis A: supernova remnant bright in X-ray
  • quasi-periodic oscillation: type of flicker of some X-ray sources
  • ROSAT: 1990s German space X-ray telescope
  • Rosat Bright Survey: list of bright X-ray sources from ROSAT observations
  • Rosat Hard Survey: list of hard X-ray sources from ROSAT observations
  • RXTE: space mission to time X-ray variations
  • scintillator: instrument part designed to respond to high-energy photons
  • Small Astronomy Satellite 3: 1970s NASA X-ray space telescope
  • SMC X-1: high-mass X-ray binary with X-ray pulsar
  • Solar Maximum Mission: 1980s satellite to study the Sun during solar maximum
  • Spektr-RG: Russian-German X-ray observatory launched in 2019
  • STAR-X: plan for a future X-ray space telescope
  • StrayCats: survey of X-ray sources detectable in NuSTAR stray light
  • STROBE-X: space X-ray telescope plan
  • Suzaku: space X-ray telescope
  • Swift: satellite for studying gamma-ray bursts
  • Uhuru: 1970 X-ray space telescope
  • ultraluminous X-ray source: X-ray source with luminosity between a star and an AGN
  • Vela: 1960s military satellites to detect nuclear tests
  • Vela supernova remnant: nearby supernova remnant
  • Wolter telescope: reflector telescope using only shallow-angle reflections
  • X-ray binary: binary star emitting X-rays
  • X-ray burster: neutron star binary producing nova-like bursts
  • X-ray flash: short flash of X-rays
  • X-ray luminosity function: maps X-ray luminosities to count of such sources
  • X-ray luminous galaxy cluster: term used for galaxy clusters found in X-ray surveys
  • X-ray pulsar: pulsar producing X-rays from accretion
  • X-ray source: astronomical object producing observable X-ray
  • XBONG: galaxy bright with X-rays but with no evident AGN
  • XEUV: electromagnetic radiation in the range of 0.15-124 nm
  • XMM Cluster Survey: survey of existing XMM-Newton data to find galaxy clusters
  • XMM-Newton: X-ray observatory-satellite operated by ESA
  • XRISM: X-ray space telescope launched in 2023
  • XTP: past plan for a space X-ray telescope
• X-ray AGN
• Rosat Bright Survey: list of bright X-ray sources from ROSAT observations
• X-ray astronomy: see X-ray source
• X-ray Astronomy Recovery Mission (XRISM): X-ray space telescope launched in 2023
• X-ray binary: binary star emitting X-rays
  • binary star: system of two stars co-orbiting
• X-ray bright optical normal galaxy (XBONG): galaxy bright with X-rays but with no evident AGN
• X-ray burst: see X-ray burster
• X-ray burst: see transient
  • X-ray binary: binary star emitting X-rays
  • X-ray flash: short flash of X-rays
• X-ray burster: neutron star binary producing nova-like bursts
  • binary star: system of two stars co-orbiting
  • X-ray binary: binary star emitting X-rays
  • X-ray flash: short flash of X-rays
• X-ray Explorer Satellite (Uhuru): 1970 X-ray space telescope
• X-ray flash: short flash of X-rays
• X-ray flash: see X-ray burster
• X-ray flashes
• localization: ability to identify location of a transient
• X-ray Imaging and Spectroscopy Mission (XRISM): X-ray space telescope launched in 2023
• X-ray luminosity function: maps X-ray luminosities to count of such sources
• X-ray luminous galaxy cluster: term used for galaxy clusters found in X-ray surveys
• X-ray microcalorimeter (microcalorimeter): instrument to measure small amounts of heat
• X-ray Multi-mirror Mission (XMM-Newton): X-ray observatory-satellite operated by ESA
• X-ray nova: see X-ray burster
• X-ray nova: see nova
  • X-ray binary: binary star emitting X-rays
• X-ray optics: see optics
• X-ray outburst (X-ray flash): short flash of X-rays
• X-ray pulsar: pulsar producing X-rays from accretion
  • binary star: system of two stars co-orbiting
  • pulsar: type of astronomical body with EMR in regular cycles of seconds or less
  • X-ray binary: binary star emitting X-rays
• X-ray source: astronomical object producing observable X-ray
  • quasi-periodic oscillation: type of flicker of some X-ray sources
  • radio source: astronomical object producing observable radio
  • source: astronomical object producing some observed signal
• X-ray Surveyor (Lynx): concept for space X-ray observatory
• X-ray TDE: see tidal disruption event
• X-ray tidal disruption event: see tidal disruption event
• X-ray Timing and Polarization (XTP): past plan for a space X-ray telescope
• X-ray Timing Explorer (RXTE): space mission to time X-ray variations
• X-ray transient: see transient
• X-ray Visionary Project
• Chandra X-ray Observatory: space X-ray telescope
• X-rays
• gas pixel detector: type of X-ray imager sensitive to polarization
• Laboratory for High Energy Astrophysics: former GSFC X-ray/gamma-ray lab of about 1970 to 2004
• proportional counter: type of ionizing-radiation sensor that senses photon energy
• X-shaped galaxy: see radio galaxy
• X-shaped radio galaxy: see radio galaxy
• X-Shooter: see European Southern Observatory Very Large Telescope
  • New Technology Telescope: 3.58-meter reflector telescope in Chile
  • PESSTO: NTT survey following up on transients
  • X-SHOOTER Lyman α survey at z = 2: survey of Lyman-α sources
  • XQR-30: ESO-VLT quasar survey
• X-SHOOTER Lyman α survey (X-SHOOTER Lyman α survey at z = 2): survey of Lyman-α sources
• X-SHOOTER Lyman α survey at z = 2: survey of Lyman-α sources
• X-spec: see CCAT
• X_CO (CO to H₂ factor): assumed ratio between observed CO emission lines and H₂ mass
  • carbon monoxide: compound of carbon and oxygen, one atom each
• x_e: see ionization fraction
• X_p: see Big Bang nucleosynthesis
• X_p: see mass fraction
  • hydrogen: most prominent element, atomic number 1
• xallarap: see gravitational microlensing
• XAO (extreme adaptive optics): high-performance version of AO system
• XARM (XRISM): X-ray space telescope launched in 2023
• XB: see X-ray burster
• XBONG: galaxy bright with X-rays but with no evident AGN
• XBS: see XMM-Newton
• Xco (CO to H₂ factor): assumed ratio between observed CO emission lines and H₂ mass
• xCOLD GASS: see COLD GASS
  • GALEX Arecibo SDSS Survey: HI survey of many galaxies
• XCS (XMM Cluster Survey): survey of existing XMM-Newton data to find galaxy clusters
  • XMM-Newton: X-ray observatory-satellite operated by ESA
• XDCP: see XMM-Newton
• XDF: see Hubble Ultra-Deep Field
• XENON: see XENON10
• xenon
• ion engine: type of electrical spacecraft engine
• LUX: experiment to identify WIMPs with a tank of xenon
• r-process: synthesis of elements through neutron capture faster than beta decay
• ZEPLIN: experiment to identify WIMPs with a tank of xenon
• xenon-136
• EXO: experiment to detect neutrinoless double beta decay in xenon
• XENON10: dark matter detector in Italy
• XENON100: see XENON10
• XENON1T: see XENON10
• XENONnT: see XENON10
• XEST: see XMM-Newton
• XEUV: electromagnetic radiation in the range of 0.15-124 nm
• XF: see spectral correlator
• XF correlator: see spectral correlator
• XF spectrometer: see spectral correlator
• XFM: see SWFO-L1
• xGASS: see GALEX Arecibo SDSS Survey
• XGBoost: machine learning software
• XGIS: see THESEUS
• XGRS: see NEAR Shoemaker
• XGS: see Lynx
• Xi Ursae Majoris
• F-type star: spectral class of star a bit hotter than then Sun
• XIS: see Suzaku
• XLF (X-ray luminosity function): maps X-ray luminosities to count of such sources
• XLS: see X-SHOOTER Lyman α survey at z = 2
• XLS-z2 (X-SHOOTER Lyman α survey at z = 2): survey of Lyman-α sources
• XLSS: see XMM-Newton
• XLSSC: see XMM-Newton
• XMM (XMM-Newton): X-ray observatory-satellite operated by ESA
• XMM Cluster Survey: survey of existing XMM-Newton data to find galaxy clusters
  • XMM-Newton: X-ray observatory-satellite operated by ESA
• XMM-LSS: see XMM-Newton
  • DEVILS: visible-light spectrographic survey of 56k distant galaxies
  • MIGHTEE: radio survey of four established deep fields
  • Spitzer Extragalactic Representative Volume Survey: infrared survey of some well-studied fields
  • Subaru XMM-Newton Deep Survey: survey using the Subaru telescope and XMM-Newton
• XMM-Newton: X-ray observatory-satellite operated by ESA
  • GOODS: survey combining data from different sources on very distant objects
  • Subaru XMM-Newton Deep Survey: survey using the Subaru telescope and XMM-Newton
  • XMM Cluster Survey: survey of existing XMM-Newton data to find galaxy clusters
• XMM-Newton Large-Scale Structure: see XMM-Newton
• XMM-Newton SAS (XMM-Newton Science Analysis System): software designed to analyze XMM-Newton X-ray data
• XMM-Newton Science Analysis System: software designed to analyze XMM-Newton X-ray data
• XMM-Newton serendipitous survey: see XMM-Newton
• XMM-SERVS: see Spitzer Extragalactic Representative Volume Survey
• XMMSL1: see XMM-Newton
• XMMU: see XMM-Newton
• XMMXCS: see XMM Cluster Survey
• XMP (extremely metal poor galaxy): galaxy of interest for its very low metallicity
• XMPG (extremely metal poor galaxy): galaxy of interest for its very low metallicity
• XN: see X-ray burster
• XO: see XO Project
• XO Cameras: see XO Project
• XO Project: initiative to search for transiting planets
  • XO-3b: unusual hot Jupiter
• XO Telescope: see XO Project
  • Haleakala Observatory: observatory on Maui, Hawaii
• XO-3: see XO-3b
• XO-3b: unusual hot Jupiter
• XQR-30: ESO-VLT quasar survey
• XRB (X-ray binary): binary star emitting X-rays
• XRB (X-ray burster): neutron star binary producing nova-like bursts
  • binary star: system of two stars co-orbiting
• XRCA: see STROBE-X
• XRF (X-ray flash): short flash of X-rays
• XRF: see X-ray burster
  • localization: ability to identify location of a transient
• XRISM: X-ray space telescope launched in 2023
  • Hitomi: 2016 Japanese space X-ray telescope
• XRO (X-ray flash): short flash of X-rays
• XRP: see Solar Maximum Mission
• XRS: see MESSENGER
• XRS: see SELENE
• XRS: see Suzaku
  • Kepler-Swift Active Galaxies and Stars Survey: X-ray/UV survey of objects within the Kepler field
• XRT: see ROSAT
• XRT: see Suzaku
• XRT: see Swift
• XSM: see SMART-1
• XSS: see RXTE
• XTE (RXTE): space mission to time X-ray variations
• Xtend: see XRISM
• XTI: see NICER
• XTP: past plan for a space X-ray telescope
• XUV (extreme ultraviolet): electromagnetic radiation in the range of 10-124 nm
• XUV flux
• habitability: ability of a planet to support life
• XVP
• Chandra X-ray Observatory: space X-ray telescope
• XZ (XZ Catalog of Zodiacal Stars): 1977 catalog of stars near the ecliptic
• XZ Catalog of Zodiacal Stars: 1977 catalog of stars near the ecliptic