Term Index (F)
Astrophysical terms and names of things beginning with the letter F.
F0
F1
F2
F3
F4
FA
FB
FC
FD
FE
FF
FG
FH
FI
FJ
FK
FL
FM
FO
FP
FR
FS
FT
FU
FV
FW
FX
FY
- F (F-type star): spectral class of star a bit hotter than then Sun
- F: see rare designator prefixes
- f (frequency): number of cycles per unit of time, such as waves per second
- F orbital: see electron orbital
- f(R) gravity: class of modifications to general relativity
- F-class star (F-type star): spectral class of star a bit hotter than then Sun
- F-D statistics
- f-mode: see asteroseismology
- F-number
- F-stop
- F-type star: spectral class of star a bit hotter than then Sun
- f-value (oscillator strength): fraction expressing QM's contribution to the probability of absorption
- F070LP: see NIRSpec
- F070W: see NIRCam
- F090W: see NIRCam
- F100LP: see NIRSpec
- F110W: see NIRSpec
- F115W: see NIRCam
- F140M: see NIRCam
- F150W: see NIRCam
- F150W2: see NIRCam
- F170LP: see NIRSpec
- F182M: see NIRCam
- F187N: see NIRCam
- F200W: see NIRCam
- F210M: see NIRCam
- F212N: see NIRCam
- F250M: see NIRCam
- F275W
- F277W: see NIRCam
- F290LP: see NIRSpec
- F2M: see rare designator prefixes
- F300M: see NIRCam
- F322W2: see NIRCam
- F355M: see NIRCam
- F356W: see NIRCam
- F360M: see NIRCam
- F410M: see NIRCam
- F430M: see NIRCam
- F444W: see NIRCam
- F460M: see NIRCam
- F480M: see NIRCam
- fsky (Fsky): fraction of the sky, e.g., what a survey covers
- F4: FRB followup project
- F=ma: see Newton's laws
- Faber-Jackson relation: relation between elliptical galaxy luminosity and stellar velocity dispersion
- Fabry-Pérot cavity (Fabry-Pérot interferometer): type of chromatic-dispersing interferometer
- Fabry-Pérot interferometer: type of chromatic-dispersing interferometer
- etalon: two parallel reflective surfaces separating light according to wavelength
- facility
- facula: bright spot on a planet or the Sun
- Fagerholm: see rare designator prefixes
- Fahrenheit
- kelvin: unit of temperature scale starting at absolute zero
- failed
- failed binary: like a binary star but one with less mass than a star
- failed binary system: see failed binary
- failed star
- brown dwarf: star-like object with less mass than a star
- faint blue galaxy: type of galaxy found much more often than expected
- faint blue galaxy problem
- Faint Images of Radio Sky at Twenty Centimeters
- USS Sources: catalog of sources with steep spectral index
- Faint Images of the Radio Sky at Twenty-centimeters (FIRST): 1990s radio survey
- Faint Infrared Grism Survey: survey to identify redshift of distant galaxies
- faint young Sun paradox: Earth had liquid water when it should have been too cold
- Fairall (Fairall Galaxy List): 1977 list of galaxies with bright nuclei
- Fairall Galaxy List: 1977 list of galaxies with bright nuclei
- Fairborn Observatory
- fallback supernova: see core collapse supernova
- falling evaporating body: icy planet/planetoid evaporating due to stellar wind
- false vacuum: apparent QFT vacuum
- false vacuum decay: see Big Crunch
- FAME (Full-sky Astrometric Mapping Explorer): early 2000s proposal for an astrometric space telescope
- Fanaroff-Riley classification: a classification of the radio characteristics of radio sources
- far infrared: infrared radiation with wavelengths in the 30-450 μm range
- Far Infrared and Submillimetre Telescope: see Herschel Space Observatory
- far ultraviolet: see ultraviolet
- Far Ultraviolet Space Telescope (FAUST): 1990s ultraviolet space telescope used on two Space Shuttle missions
- Far Ultraviolet Spectroscopic Explorer: early 2000s space telescope for short-wavelength ultraviolet
- far-infrared astronomy
- far infrared: infrared radiation with wavelengths in the 30-450 μm range
- far-IR (far infrared): infrared radiation with wavelengths in the 30-450 μm range
- Faraday effect (Faraday rotation): rotation of optical polarization by a medium in a magnetic field
- Faraday rotation: rotation of optical polarization by a medium in a magnetic field
- Faraday tomography: see tomography
- Farnese Atlas: see Hipparchus
- FAST: Arecibo-like 500 m telescope in China
- Fast and Fortunate for FRB Follow-up (F4): FRB followup project
- fast blue optical transient: optical transient with rise time under five days
- fast folding algorithm: algorithm to find the periods of periodic data
- fast Fourier transform: efficient algorithm for calculating a discrete Fourier transform
- Fast Fourier Transform Telescope: proposed all-digital telescope with synthetic aperture
- Fast Infrared Exoplanet Spectroscopy Survey Explorer (FINESSE): planned space mission for exoplanet spectrography
- fast moving object: see near-Earth object
- Fast On-orbit Rapit Recording of Transient Events: satellite viewing radio and optical transients on Earth
- fast optical burst: see fast radio burst
- fast radio burst: astronomical high energy radio pulses of a few milliseconds
- fast radio bursts
- fast radio transient (fast radio burst): astronomical high energy radio pulses of a few milliseconds
- fast radio transients
- STARE: array of radio telescopes monitoring radio transients
- fast rise exponential decay GRB: see gamma-ray burst
- fast shock: see shock wave
- fast-spinning Earth model: see Moon formation
- Fastest Fourier Transform in the West: code library implementing efficient FFT
- FastPDI: see Subaru Telescope
- FASTT: see USNO
- Faulkes Telescope North
- FAUST: 1990s ultraviolet space telescope used on two Space Shuttle missions
- FBG (faint blue galaxy): type of galaxy found much more often than expected
- FBOT (fast blue optical transient): optical transient with rise time under five days
- FBQS: see FIRST
- FBS: see Second Byurakan Survey
- FC: see Dawn
- FCC: see rare designator prefixes
- FCRAO (Five College Radio Astronomical Observatory): former observatory near Springfield MA
- FDM (finite difference method): means of estimating calculus and differential equation solutions
- FDM (fuzzy dark matter): concept of extremely light dark matter particles
- FDM: see dark matter
- Fe (iron): metal, Fe, atomic number 26
- Fe XXVI: see iron
- Fe XXVII: see iron
- ion: non-neutral atom or molecule, with missing or extra electrons
- FE1: see Fly's Eye
- FE2: see Fly's Eye
- FEA (finite element method): computational method for PDEs suited to physical problems
- feature (spectral feature): recognizable feature of a spectrum
- FEB (falling evaporating body): icy planet/planetoid evaporating due to stellar wind
- feedback (star formation feedback): mechanisms whereby star formation regulates its own rate
- Feedback in Realistic Environments (FIRE Simulations): high resolution simulation of galaxies
- feedhorn: feature of microwave receivers
- feedhorn array: see feedhorn
- feedhorn array: see focal plane array
- FEEPS: see Magnetospheric Multiscale Mission
- Feige: see rare designator prefixes
- feldspar
- basalt: an igneous rock type that shows rapid cooling
- FEM (finite element method): computational method for PDEs suited to physical problems
- Fenton Hill Observatory: New Mexico GRB-oriented astronomical observatory
- Milagro: gamma ray telescope using Cherenkov radiation
- RAPTOR: automated array of telescopes to uncover and track transients
- FERMI
- Fermi: satellite for studying gamma rays
- Fermi bubbles: gamma-ray features associated with Milky Way center
- Fermi bubbles: gamma-ray features associated with Milky Way center
- Fermi energy: see Fermi sea
- Fermi Gamma-ray Space Telescope (Fermi): satellite for studying gamma rays
- Fermi level: see Fermi sea
- Fermi problem: see back-of-the-envelope calculation
- Fermi sea: atom's minimal-energy electrons filling its lower shells
- Fermi surface: see Fermi sea
- Fermi-Dirac distribution
- Fermi-Dirac statistics
- Fermi-LAT: see Fermi
- fermion: see particle
- Bose-Einstein statistics: possible distribution of particles not bound by Pauli exclusion
- electron: type of lepton that is stable and has an electric charge of -1
- hyperon: exotic type of baryon
- lepton: elementary particle with 1/2 integer spin such as electron
- neutrino: light, electrically neutral elementary particle
- Pauli exclusion principle: fermions in a quantum system cannot have identical quantum numbers
- quark: type of elementary particle incorporated in protons and neutrons
- spin: an angular-momentum quantum number
- Ferrel cell
- Hadley cell: circulation pattern of up at the equator, poleward, down, and back
- Ferrero: see rare designator prefixes
- ferromagnetism: see magnetic field
- FeSt: see rare designator prefixes
- FET
- FFA (fast folding algorithm): algorithm to find the periods of periodic data
- FFP (free-floating planet): planet that is not orbiting a star
- FFT (fast Fourier transform): efficient algorithm for calculating a discrete Fourier transform
- FFT Telescope (Fast Fourier Transform Telescope): proposed all-digital telescope with synthetic aperture
- FFTW (Fastest Fourier Transform in the West): code library implementing efficient FFT
- Fg: see rare designator prefixes
- FGC: see rare designator prefixes
- FGI: see QUIJOTE
- FGK star: a star of the "middle" spectral classes, F, G, and K
- FGL: see Fermi
- FGLR (flux-weighted gravity-luminosity relationship): method of determining luminosity of distant stars
- FGM: see Ulysses
- THEMIS: set of satellites studying the Earth's magnetic field
- FGS: see Hubble Space Telescope
- FGS: see James Webb Space Telescope
- SH0ES: survey to increase the accuracy of the cosmic distance ladder
- FGST (Fermi): satellite for studying gamma rays
- FHO (Fenton Hill Observatory): New Mexico GRB-oriented astronomical observatory
- FHST: see Hubble Space Telescope
- fiber: see integral field spectrograph
- fiber positioner: machine to set up fibers in multi-object spectrograph
- fiber-linked optical array telescope: scheme for a type of multi-mirror telescope
- Fick's laws: see diffusion
- Fickian diffusion: see diffusion
- fictitious force: see inertial reference frame
- fiducial: taken as a standard
- fiducial inference: see fiducial
- fiducial mark: see fiducial
- fiducial marker: see fiducial
- fiducial model: see fiducial
- field: adjective meaning "in this field of view but unrelated"
- field (field of view): angular measure of how much an optical instrument can view
- field (mathematical field): function of three variables, potentially representing space
- field (physical field): physical property of some volume of space
- field (survey field): portion of the celestial sphere where a survey's observations aim
- field brown dwarf: see field
- field curvature: focusing to a curved surface rather than a plane
- field equation
- Big Bang: theoretical event when the universe expanded from a point
- field flattener lens: see field curvature
- field galaxy: galaxy not in a cluster or group
- field lines: lines showing the pattern of a mathematical field
- field object: see field
- Field of Streams: region of sky crossed by a number of stellar streams
- field of view: angular measure of how much an optical instrument can view
- field of vision (field of view): angular measure of how much an optical instrument can view
- field planet (free-floating planet): planet that is not orbiting a star
- field planet: see field
- field spectrometer (imaging spectrometer): device to capture spectrum point-by-point of an image
- spectroscopy: measurement of light with various electromagnetic wavelengths
- field star: star that is not part of a star cluster
- field-effect transistor
- field-programmable gate array: type of customizable digital electronic circuit
- FIELDS: see Parker Solar Probe
- FIFI-LS: see SOFIA
- FIGS (Faint Infrared Grism Survey): survey to identify redshift of distant galaxies
- figure: see theory of figures
- figure of a planet: see theory of figures
- figure of the Earth
- filament: linear volume of high molecular gas density within a galaxy
- filament (galaxy filament): thread-like formations of galaxies, 50 to 80 megaparsecs
- Nessie: star-forming filament found in the Orion star-forming region
- filled ice: see clathrate
- filter: optical device to filter out part of the EMR spectrum
- filter (passband): range of electromagnetic wavelengths that a filter allows
- B: photometric filter for blue light
- bandpass filter: device to filter away all but a band of frequencies
- G band: band of visible light around 5100 angstroms
- I band: passband for near-infrared light
- R band: band of visible light around 6500 angstroms
- U: photometric filter for ultraviolet light
- V: photometric filter for visible light
- filter bank: set of filters to simultaneously produce radio data within bands
- DESHIMA: submillimeter spectrometer
- filter designator: indicators of a filter used in imaging
- filterbank (filter bank): set of filters to simultaneously produce radio data within bands
- filters
- FIN: see double star designation
- final data release: see data release
- final parsec problem: lack of a convincing theory on how SMBHs can reach each other
- fine structure: separate spectral lines due to electron spin and relativistic effects
- hyperfine structure: spectral lines from magnetic and spin interactions between electrons and nucleus
- fine structure constant: see fine structure
- fine structure line: see fine structure
- FINESSE: planned space mission for exoplanet spectrography
- finger of God distortion: see redshift space
- finite difference method: means of estimating calculus and differential equation solutions
- finite element analysis (finite element method): computational method for PDEs suited to physical problems
- finite element method: computational method for PDEs suited to physical problems
- finite volume method: computational method for PDEs especially suited to fluid dynamics
- finite-volume method
- MITgcm: well-known general circulation model
- FIP: see Origins Space Telescope
- FIR (far infrared): infrared radiation with wavelengths in the 30-450 μm range
- FIRAS: see Cosmic Background Explorer
- FIRE: see Magellan Telescopes
- FIRE Simulations: high resolution simulation of galaxies
- FIRE-2: see FIRE Simulations
- fireball: see meteoroid
- FIRESS: see PRIMA
- Fireworks Galaxy (NGC 6946): face-on spiral galaxy
- FIRST: 1990s radio survey
- FIRST: see Herschel Space Observatory
- USS Sources: catalog of sources with steep spectral index
- first dredge-up: see dredge-up
- first galaxies: targeted highest red-shift galaxies showing little or no metal
- First Large Absorption Survey in HI: see Australian Square Kilometre Array Pathfinder
- first light: initial demonstration that a telescope works
- first order perturbation problem: see perturbation theory
- first point of Aries: see equinox
- first-light instrument: see first light
- first-order TOF: see theory of figures
- FIS: see AKARI
- Fisher information: measure of the information provided by experimental data
- Fisher information matrix: see Fisher information
- Fisher matrix: see Fisher information
- Fisher method: see Fisher information
- Fisher score (Fisher information): measure of the information provided by experimental data
- Fisher technique: see Fisher information
- FISS: see Big Bear Solar Observatory
- fission: see fusion
- FITS: IAU standard for data such as images
- SPECTRE: an interactive spectrum analysis software package
- Five College Consortium
- Five College Radio Astronomical Observatory: former observatory near Springfield MA
- Five Hundred Meter Aperture Spherical Telescope (FAST): Arecibo-like 500 m telescope in China
- fixed star: star that does not change position in the celestial sphere
- FJF: see rare designator prefixes
- FJR (Faber-Jackson relation): relation between elliptical galaxy luminosity and stellar velocity dispersion
- FK Comae Berenices variable: see variable star
- FK4: see Catalogues of Fundamental Stars
- FK4: see celestial reference frame
- FK5: see Catalogues of Fundamental Stars
- FK5: see celestial reference frame
- Flagship Mission
- Lynx: concept for space X-ray observatory
- Flagship Missions
- NASA: includes space-based astronomy research
- Flagstaff Astrometric Scanning Transit Telescope: see USNO
- FLAMES: see European Southern Observatory Very Large Telescope
- FLAMINGOS-2: see Gemini Observatory
- Flamsteed designation: star designation system dating from 1700s
- FLAO: see Large Binocular Telescope
- flare spray: see solar eruption
- flare star: see stellar flare
- flaring state
- FLASH: hydrodynamic simulation system
- FLASH: see Atacama Pathfinder Experiment
- FLASH: see Australian Square Kilometre Array Pathfinder
- Flash Center for Computational Science
- FLASH: hydrodynamic simulation system
- FLASH+: see Atacama Pathfinder Experiment
- flat universe: see Einstein-de Sitter model
- flat universe: see critical density
- flatness problem: see inflation
- flavor: subtype of some type of particle
- flavor: see quark
- electron: type of lepton that is stable and has an electric charge of -1
- hyperon: exotic type of baryon
- neutrino oscillation: neutrinos regularly morph into another flavor
- quark matter: matter not made of protons and neutrons but of quarks
- tau neutrino: neutrino flavor that becomes a tau particle during interactions
- flavor morphing
- Flexible Image Transport System (FITS): IAU standard for data such as images
- SPECTRE: an interactive spectrum analysis software package
- Flexible Modeling System
- TAM: non-gray-RT 3D model of Titan's atmosphere
- Flexible Stellar Population Synthesis (FSPS): code library for stellar population synthesis
- FLITECAM: see SOFIA
- FLOAT (fiber-linked optical array telescope): scheme for a type of multi-mirror telescope
- flocculent spiral galaxy: see spiral galaxy
- Flora
- Flow: see GRAIL
- FLS: see Spitzer Space Telescope
- fluence: see flux
- fluffy CAI: see CAI
- fluid dynamics: see hydrodynamics
- fluid mechanics
- fluorescence: emission from a molecule excited by absorption
- fluorescence protection: see biofluorescence
- fluorescent lamp
- fluorescence: emission from a molecule excited by absorption
- fluorescent protein: see biofluorescence
- fluoride: see geochemistry
- fluorine
- geochemistry: the chemistry of the Earth, planets, and moons
- flux: flow rate per unit area
- Gini/M20: an automatable method of detecting whether a galaxy has recently merged
- PCA analysis: an automatable method of determining galaxy morphology
- solar constant: flux from the Sun at 1 AU
- spectral flux density: flux or power of radiation per unit area per unit wavelength
- flux density: measure of the strength of a radio signal
- flux density (flux): flow rate per unit area
- flux freezing: magnetic field lines becoming attached to plasma they pass through
- flux index (chromospheric activity index): measure of magnetic activity of a star's chromosphere
- flux reconstruction: numerical approach emphasizing joining the subdivisions
- flux rope: rope-shaped structure in magnetic fields associated with coronal mass ejections
- flux-weighted gravity-luminosity relationship: method of determining luminosity of distant stars
- FLWO (Fred Lawrence Whipple Observatory): observatory near Amado, Arizona
- VERITAS: ground gamma ray telescope array in Arizona
- Fly's Eye: 1980s cosmic-ray observatory
- Fly's Eye 2: see Fly's Eye
- Fly's Eye HiRes (High Resolution Fly's Eye): 1990s-2000s cosmic-ray observatory
- CASA-MIA: 1990s cosmic-ray detector in Utah
- flyby: space probe flying close to a planet or moon
- Mars: well-explored planet in the solar system
- FM (frequency modulation): changing the frequency of a signal's carrier
- FM: see rare designator prefixes
- FMM: see rare designator prefixes
- FMO: see near-Earth object
- FMOS: see Subaru Telescope
- FMS
- TAM: non-gray-RT 3D model of Titan's atmosphere
- FOB: see fast radio burst
- FOC: see Hubble Space Telescope
- focal length: length from optical element to focal plane
- focal plane: plane within optical system at which an image is in focus
- focal plane: plane within optical system at which an image is in focus
- focal plane array: array of receivers at the focus of a radio telescope
- focal plane tilt: focal plane not perpendicular to the optical axis
- focal point: see focal plane
- focal ratio
- FOCAS: see Subaru Telescope
- foe: unit of energy on the order of a supernova's output
- energy: physical state needed to do something
- Fokker-Planck equation: shows likelihood of velocity over time of a disturbed particle
- Fokker-Planck equation: see stellar dynamics
- Fokker-Planck limit: see stellar dynamics
- fold mirror: flat mirror in a telescope to redirect the light
- folding mirror (fold mirror): flat mirror in a telescope to redirect the light
- foot-pound: see energy
- forbidden line: spectral line that quantum mechanics disallows for the most part
- forbidden mechanism: see forbidden line
- forbidden transition: see forbidden line
- forbidden zone: see Hayashi limit
- Forbush decrease: decrease in cosmic rays after a coronal mass ejection
- Forbush effect (Forbush decrease): decrease in cosmic rays after a coronal mass ejection
- FORCAST: see SOFIA
- forced libration: see libration
- Enceladus: Saturn moon considered possible carrier of life
- foreground subtraction: removing unwanted sources of EMR in intensity mapping
- formation of the Moon (Moon formation): process by which the Moon and other moons formed
- FORNAX: hydrodynamics simulation software
- Fornax Cluster
- Fornax Dwarf
- Fornax Wall: see galaxy filament
- FORS1: see European Southern Observatory Very Large Telescope
- FORS2: see European Southern Observatory Very Large Telescope
- FORTE (Fast On-orbit Rapit Recording of Transient Events): satellite viewing radio and optical transients on Earth
- forward Fourier transform: see Fourier transform
- forward model: model producing potential observable values from parameters
- retrieval: determining parameters through observation and modeling
- Tau-REx: spectral line retrieval code for exoplanet atmospheres
- FOS: see Hubble Space Telescope
- FOS-1: see Isaac Newton Telescope
- fossil group: apparent remnant of a galaxy group
- fossil radio plasma: see radio relics
- four-body problem: see N-body problem
- Four-shooter: see Hale Telescope
- Fourier analysis
- linear theory: theory of operators satisfying the property of superposition
- Fourier coefficients: see Fourier series expansion
- Fourier domain (Fourier space): domain into which the Fourier transform maps a function
- Fourier series: type of series able to approximate a periodic function
- Fourier series expansion: type of series expansion of a function using trigonometric functions
- Fourier series expansion: see Fourier series
- Fourier space: domain into which the Fourier transform maps a function
- Fourier transform: systematic method of breaking down functions into periodic components
- Fourier transform spectrometer: see imaging Fourier transform spectroscopy
- Fourier transform spectroscopy: see imaging Fourier transform spectroscopy
- FourStar: see Magellan Telescopes
- FourStar Galaxy Evolution Survey: infrared deep-survey to detect galaxies
- Fourth Cambridge Catalog of Radio Sources: 1960s catalog of northern hemisphere 178 MHz sources
- Fourth Cambridge Survey (Fourth Cambridge Catalog of Radio Sources): 1960s catalog of northern hemisphere 178 MHz sources
- FOV (field of view): angular measure of how much an optical instrument can view
- FOV: see rare designator prefixes
- FOX: see double star designation
- FPA (focal plane array): array of receivers at the focus of a radio telescope
- FPCS: see HEAO-2
- FPGA (field-programmable gate array): type of customizable digital electronic circuit
- FPI (Fabry-Pérot interferometer): type of chromatic-dispersing interferometer
- FPI: see Magnetospheric Multiscale Mission
- FR (flux reconstruction): numerical approach emphasizing joining the subdivisions
- FR 1: see Fanaroff-Riley classification
- FR 2: see Fanaroff-Riley classification
- FR classification (Fanaroff-Riley classification): a classification of the radio characteristics of radio sources
- FR-I: see Fanaroff-Riley classification
- FR-II: see Fanaroff-Riley classification
- fraction of the sky (Fsky): fraction of the sky, e.g., what a survey covers
- fractionation: separation of one chemical mixture into others
- abundances: relative amounts of each chemical element
- fractionation factor: isotope-related ratio
- fragmentation barrier: the problem that the seeds of planets would break apart rather than merge
- fragmentation barrier: see meter size barrier
- barrier: challenging issue regarding planet formation
- frame dragging: region of space dragged into rotation by a rotating object
- frame dragging: see frame dragging
- frame of reference: region, possibly in motion, from which something is observed/considered
- reduced mass: the reciprocal of the sum of the reciprocals of the masses of two objects
- relativity: physics models accommodating the constancy of the speed of light
- France
- Frank Ross's Catalog: high-proper-motion and variable stars catalogued by Frank Ross
- Frank Ross's List (Frank Ross's Catalog): high-proper-motion and variable stars catalogued by Frank Ross
- Fraunhofer diffraction
- diffraction: an effect of the edge of an obstacle on a wave
- Fraunhofer lines: dark lines discovered in the Sun's spectrum two centuries ago
- G band: band of visible light around 5100 angstroms
- Fraunhofer Telescope: see Wendelstein Observatory
- Fraunhofer's G band: see G band
- FRB (fast radio burst): astronomical high energy radio pulses of a few milliseconds
- FRB 010724: see fast radio burst
- FRB 121102: see fast radio burst
- FRB 20121102 (FRB121102): first repeating FRB discovered
- FRB 20121102A (FRB121102): first repeating FRB discovered
- FRB Catalogue: see fast radio burst
- FRB Community Newsletter: periodical message about fast radio bursts
- FRB Newsletter (FRB Community Newsletter): periodical message about fast radio bursts
- FRB non-repeater: see fast radio burst
- FRB repeater: see fast radio burst
- FRB source: see fast radio burst
- FRB source: see source
- FRB121102: first repeating FRB discovered
- FRB200428: see SGR 1935+2154
- FRBCAT: see fast radio burst
- FRBs
- FRED GRB: see gamma-ray burst
- Fred Lawrence Whipple Observatory: observatory near Amado, Arizona
- IOTA: past optical interferometer in Arizona
- MMT: 6.5 meter telescope at Mt. Hopkins, Arizona
- VERITAS: ground gamma ray telescope array in Arizona
- Fred Young Submillimeter Telescope: 6-meter submillimeter survey telescope under construction in Chile
- Frederick C. Gillett Gemini Telescope: see Gemini Observatory
- free atmosphere: see planetary boundary layer
- free electron
- free expansion phase: see supernova remnant
- free floating planet
- free neutron: see neutron
- free neutron: see neutron capture
- free neutron mean lifetime: see neutron capture
- free neutrons
- free streaming: particles moving long distances without disturbance
- free streaming length: see free streaming
- free streaming scale: see free streaming
- free-air anomaly: gravity's local variation after compensating for altitude
- Bouguer anomaly: gravity's local variation after compensating for altitude and landforms
- free-air correction: see free-air anomaly
- free-air gravity: see free-air anomaly
- free-air gravity anomaly (free-air anomaly): gravity's local variation after compensating for altitude
- free-air gravity map: see free-air anomaly
- free-bound emission
- recombination: time when the universe's ionized hydrogen atoms neutralized
- free-fall time: time it would take a body to collapse if unopposed
- free-fall timescale: see free-fall time
- free-fall timescale: see timescale
- free-floating: see field
- free-floating planet: planet that is not orbiting a star
- free-floating planet: see field
- free-free
- free-free absorption: see bremsstrahlung
- free-free radiation (bremsstrahlung): photon emission when a charged particle is decelerated
- Freeman law (Freeman's law): all spiral galaxy's have the same central surface brightness
- Freeman's law: all spiral galaxy's have the same central surface brightness
- freeze-out: particles existing long-term after a decoupling
- FREGATE: see High Energy Transient Explorer
- French Astronomical Society (Société astronomique de France): French non-profit astronomical society
- FREND: see Trace Gas Orbiter
- frequency: number of cycles per unit of time, such as waves per second
- frequency domain (Fourier space): domain into which the Fourier transform maps a function
- frequency modulation: changing the frequency of a signal's carrier
- frequentist statistics: see Bayesian statistics
- Fresnel diffraction
- diffraction: an effect of the edge of an obstacle on a wave
- FRI: see Fanaroff-Riley classification
- Fried parameter: see seeing
- Friedmann equation: see Friedmann model
- Friedmann model: type of model of universe incorporating general relativity
- Friedmann universe (Friedmann model): type of model of universe incorporating general relativity
- Friedmann-Lemaitre universe (Friedmann model): type of model of universe incorporating general relativity
- FRIEND: see CHARA
- FRII: see Fanaroff-Riley classification
- FRK: see double star designation
- Frl (Fairall Galaxy List): 1977 list of galaxies with bright nuclei
- FRODOSpec: see Liverpool Telescope
- front end (front end instrument): instruments of a telescope that detect and encode the signal
- front end instrument: instruments of a telescope that detect and encode the signal
- Frontier
- frost line (snow line): distance from protostar so cool that water condenses
- FRT (fast radio burst): astronomical high energy radio pulses of a few milliseconds
- FS: see rare designator prefixes
- FSC: see IRAS
- Fsky: fraction of the sky, e.g., what a survey covers
- FSO: see rare designator prefixes
- FSP: see rare designator prefixes
- FSPS: code library for stellar population synthesis
- FSR: see rare designator prefixes
- FT (Fourier transform): systematic method of breaking down functions into periodic components
- FTL: "faster than light"
- FTL: see superluminal motion
- FTM: see rare designator prefixes
- FTS: see imaging Fourier transform spectroscopy
- FU Ori: see FU Orionis star
- FU Ori star (FU Orionis star): type of variable pre-main-sequence star
- FU Orionis: see FU Orionis star
- FU Orionis object (FU Orionis star): type of variable pre-main-sequence star
- FU Orionis star: type of variable pre-main-sequence star
- Fugaku: Japanese petaflop/exaflop supercomputer
- full duration: see transiting planet
- full width at half maximum: a measure of the width of a hump-shaped curve
- full width at zero intensity: see full width at half maximum
- Full-sky Astrometric Mapping Explorer: early 2000s proposal for an astrometric space telescope
- full-wave plate: see waveplate
- fullerine: see polycyclic aromatic hydrocarbon
- fully-stripped supernova: see core collapse supernova
- Fulton gap: planets with radius 1.5 to 2 Earth radii are rare
- super-Earth: exoplanet more massive than Earth but substantially less than Neptune
- function
- function space
- basis function: one of a set of functions used to approximate a function of interest
- functional group: see hydroxyl
- fundamental ephemeris: see ephemeris
- fundamental plane: three-way relation between elliptical galaxy characteristics
- Funnelweb Survey
- TAIPAN: multi-object spectrograph with robot fiber-positioner
- FUor (FU Orionis star): type of variable pre-main-sequence star
- Furuhjelm: see rare designator prefixes
- FUSE (Far Ultraviolet Spectroscopic Explorer): early 2000s space telescope for short-wavelength ultraviolet
- fusing: see fusion
- fusion: formation of an atomic nucleus nuclei from multiple smaller nuclei
- fusor: 2003 proposed term for astronomical objects capable of carrying out fusion
- future
- FUV: see IMAGE
- FUV: see ultraviolet
- FUVITA: see Spektr-RG
- fuzzball: theoretical alternative to black holes based on superstring theory
- fuzzy cold dark matter (fuzzy dark matter): concept of extremely light dark matter particles
- fuzzy cold dark matter: see dark matter
- fuzzy dark matter: concept of extremely light dark matter particles
- fuzzy dark matter: see dark matter
- FVM (finite volume method): computational method for PDEs especially suited to fluid dynamics
- MITgcm: well-known general circulation model
- FWHM (full width at half maximum): a measure of the width of a hump-shaped curve
- FWO (Research Foundation - Flanders): Belgian research council
- FWZI: see full width at half maximum
- FX: see spectral correlator
- FX correlator: see spectral correlator
- FX spectrometer: see spectral correlator
- FX140X: see NIRSpec
- FXT: see Einstein Probe
- FYST (Fred Young Submillimeter Telescope): 6-meter submillimeter survey telescope under construction in Chile
- Atacama Desert: Chilean high-altitude, dry plateau with numerous observatories
Index