Term Index (L)
Astrophysical terms and names of things beginning with the letter L.
L1
L2
L3
L4
L5
LA
LB
LC
LD
LE
LF
LG
LH
LI
LK
LL
LM
LN
LO
LP
LQ
LR
LS
LT
LU
LV
LW
LX
LY
LZ
- L (L-type star): spectral type of star cooler than an M-type star
- L (Lyman series): hydrogen series from electrons settling from n > 1 to n = 1
- L (Lynds Catalog of Dark Nebulae): 1950s/1960s list of dark nebulae found on Palomar plates
- L (luminosity): measure of brightness
- L: see double star designation
- L: see rare designator prefixes
- l: see Love number
- l: see electron orbital
- L band: see infrared
- L dwarf: see L-type star
- brown dwarf: star-like object with less mass than a star
- Lépine Shara Proper Motion catalog: 2000s catalog of stars with proper motion
- L'institute Canadian d'astrophysique théorique (Canadian Institute for Theoretical Astrophysics): national research organization at University of Toronto
- L'LORRI: see Lucy
- L'Ralph: see Lucy
- L'TES: see Lucy
- L-αintergalactic clouds
- Lyman-alpha forest: overlaid redshifted Lyman-alpha absorption lines on light from distant objects
- L-class: see L-type star
- l-m plane: see u-v plane
- L-point (Lagrangian point): points around two orbiting bodies where small objects can sit
- L-type star: spectral type of star cooler than an M-type star
- L1: see Lagrangian point
- L1527 (LDN 1527): dark nebula in Taurus
- L1527 IRS: see LDN 1527
- L1689 (LDN 1689): dense core within the Rho Ophiuchi Cloud Complex
- L2: see Lagrangian point
- L3: see Lagrangian point
- L4: see Lagrangian point
- 2010 TK7: asteroid that is an Earth Trojan
- L483: protostar of interest
- L5: see Lagrangian point
- ESA Vigil: plan for space-weather warning satellite at L5
- L☉ (solar luminosity): luminosity unit representing the luminosity of the Sun
- L500: see cluster radius
- LBol (bolometric luminosity): total luminosity of an object at all wavelengths
- LIR: see infrared
- LSun (solar luminosity): luminosity unit representing the luminosity of the Sun
- energy: physical state needed to do something
- luminosity: measure of brightness
- watt: SI unit of power
- LTIR (total infrared luminosity): luminosity over a wide IR range
- LX: see Sunyaev-Zel'dovich effect
- La Palma
- La Palma Observatory (Roque de los Muchachos Observatory): observatory at La Palma in the Canary Islands
- La Silla Observatory: Atacama-desert observatory run by ESO
- La Silla Paranal Observatory: manages three ESO observatory-sites in Chile
- LA-COMPASS: MHD-capable hydrodynamic code
- LAB (Lyman-alpha blob): Lyman-alpha emitting cloud larger than a galaxy
- LABOCA: see Atacama Pathfinder Experiment
- LABOCA ECDFS Submillimeter Survey
- LABOCA ECDFS Submm Survey (LABOCA Extended Chandra Deep Field-South Submillimetre Survey): submillimeter survey of a well-studied piece of sky
- LABOCA Extended Chandra Deep Field-South Submillimetre Survey: submillimeter survey of a well-studied piece of sky
- Laboratori Nazionali del Gran Sasso
- DAMA/LIBRA: dark matter detection experiment in Italy
- Laboratorio de Astrofisica Espacial y Fisica Fundamental: Spanish astrophysics laboratory
- Laboratory Astrophysics Division (LAD): AAS division supporting laboratory work relevant to astrophysics
- Laboratory for High Energy Astrophysics: former GSFC X-ray/gamma-ray lab of about 1970 to 2004
- LAC: see Ginga
- Lac (Lacaille Star Catalog): 1700s catalog of about 10,000 southern hemisphere stars
- Lac 9352 (Lacaille 9352): red dwarf that is the twelfth nearest star system
- Lacaille: see Lacaille Star Catalog
- Lacaille 9352: red dwarf that is the twelfth nearest star system
- Lacaille Star Catalog: 1700s catalog of about 10,000 southern hemisphere stars
- LAD: AAS division supporting laboratory work relevant to astrophysics
- LAD: see STROBE-X
- LAD: see eXTP
- LAD-C (Large Area Debris Collector): planned ISS instrument to collect space debris for analysis
- LAE (Lyman-alpha emitter): redshifted galaxy emitting the Lyman alpha line
- GLARE: project to search for distant star-forming galaxies
- LAEDI (Lock-In Amplified Externally Dispersed Interferometry): technique for precise RV measurement
- LAEFF (Laboratorio de Astrofisica Espacial y Fisica Fundamental): Spanish astrophysics laboratory
- Laevens: see rare designator prefixes
- Laevens 2 (Triangulum II): dwarf galaxy in the Local Group
- Lagrange: see ESA Vigil
- Lagrange point (Lagrangian point): points around two orbiting bodies where small objects can sit
- Lagrange point stability: see Lagrangian point
- Lagrange stability: a quality of some stable orbits
- Lagrangian code: see stellar structure
- Lagrangian libration point (Lagrangian point): points around two orbiting bodies where small objects can sit
- Lagrangian point: points around two orbiting bodies where small objects can sit
- LAL: see rare designator prefixes
- Lalande: see rare designator prefixes
- Lalande 21185: nearby red dwarf
- Lalande 21185 b: see Lalande 21185
- LALT: see SELENE
- LAM: see double star designation
- LAMBDA: NASA archive center re CMB data
- LAMBDA: see RADEX
- lambda (cosmological constant): force counteracting the universe's inward gravitational pull
- lambda (dark energy): energy theorized to accelerate the expansion of the universe
- Lambda Boötis star: peculiar star with metallicity only with lighter elements
- Lambda-CDM
- sigma-8 tension: Lambda CDM anomaly regarding matter fluctuation
- wCDM: Big-Bang cosmological model with constant cosmological equation of state
- Lambda-CDM model: Big-Bang cosmological model with a cosmological constant and cold dark matter
- laminar flow: see turbulence
- Rayleigh number: measure reflecting a fluid system's propensity to convection
- Reynolds number: measure reflecting a fluid system's propensity to turbulence
- LAMOST: Chinese telescope for spectroscopic surveys of stars and galaxies
- LAMOST DR12: see LAMOST
- LAMOST DR5: see LAMOST
- LAMOST Experiment for Galactic Understanding and Evolution: see LAMOST
- LAMOST Extragalactic Survey: see LAMOST
- LAMOST II: see LAMOST
- LAMP: see Lunar Reconnaissance Orbiter
- lamppost model: see AGN corona
- Landau damping: type of damping of waves that occurs in thin plasma
- Landau-Oppenheimer-Volkoff limit (Tolman-Oppenheimer-Volkoff limit): maximum mass of a neutron star
- Landsat 7
- OSAM-1: prototype space robot for servicing satellites
- Lane-Emden equation: form of equation of state for gas ball in hydrostatic equilibrium
- Langmuir probe: plasma sensor
- Langmuir waves: see plasma frequency
- Laniakea (Laniakea Supercluster): group of clusters including the Local Group
- Laniakea Supercluster: group of clusters including the Local Group
- Lanning: see rare designator prefixes
- lanthanide: element having atomic number within 57 through 71
- kilonova: transient associated with merging neutron stars
- lanthanide nucleosynthesis: see lanthanide
- lanthanum: see lanthanide
- Laplace plane: see Laplace radius
- Laplace radius: a radius for a stable orbit of a satellite around a planet
- Laplace resonance: see orbital resonance
- Laplace spherical harmonics: see spherical harmonics
- Laplace surface: see Laplace radius
- Laplace's equation: see Poisson's equation
- Laplace-Lagrange secular evolution theory (Laplace-Lagrange secular theory): theory of evolution of planetary orbits
- Laplace-Lagrange secular theory: theory of evolution of planetary orbits
- Laplacian: see Poisson's equation
- LARES: satellite to test a general relativity effect
- LARES 2: see LARES
- Large Altazimuth Telescope: 6-meter reflector telescope in Russia
- Large Aperture Telescope: see Simons Observatory
- Large Area Debris Collector: planned ISS instrument to collect space debris for analysis
- Large Binocular Telescope: dual 8.4 meter telescope in Arizona
- Large Binocular Telescope Interferometer: see Large Binocular Telescope
- Large Bright QSO Survey: 1980s quasar survey
- Large Bright Quasar Survey (Large Bright QSO Survey): 1980s quasar survey
- Large Earth Finder (G-CLEF): spectrograph on the GMT
- Large Earth-based Solar Telescope: 1990s plan for 2.4 m solar telescope
- Large European Array for Pulsars: see European Pulsar Timing Array
- Large Hadron Collider
- Large High Altitude Air Shower Observatory (LHAASO): gamma ray/cosmic ray observatory in China
- Large Magellanic Cloud: somewhat irregular satellite galaxy of the Milky Way
- Large Millimeter Telescope: large microwave telescope in Mexico
- TolTEC: sensitive infrared camera under construction for the LMT
- Large Quasar Group
- Huge-LQG: possible overly-large structure
- large quasar group: structure consisting of a collection of quasars
- Large Scale Cryogenic Gravitational Wave Telescope (KAGRA): gravitational wave detector in Japan preparing for operation
- large scale streaming motion
- large scale structure: the universe's structure as in placement of clusters
- large scale structure of the universe (large scale structure): the universe's structure as in placement of clusters
- large scale structures
- galaxy bias: degree to which galaxy density fails to correspond to dark matter density
- supercluster: cluster of galaxy clusters
- void: empty spaces between large scale structures
- Large Size Telescope
- Large Sky Area Multi-object Fibre Spectroscopic Telescope (LAMOST): Chinese telescope for spectroscopic surveys of stars and galaxies
- Large Strategic Science Mission
- Large Strategic Science Missions
- NASA: includes space-based astronomy research
- Large Submillimeter Telescope: concept for a 50-meter submillimeter telescope in Chile
- Large Suite of Dark Matter Simulations (LasDamas): simulations of large scale evolution of dark matter and galaxies
- Large Synoptic Survey Telescope (Rubin Observatory): 8-meter survey reflector telescope under construction in Chile
- Large Underground Xenon experiment (LUX): experiment to identify WIMPs with a tank of xenon
- Large Underground Xenon experiment: see ZEPLIN
- Large UV/Optical/Infrared Surveyor (LUVOIR): plan for a space-based telescope
- Large Zenith Telescope: 6 meter liquid mirror telescope in British Columbia
- Large-aperture Experiment to detect the Dark Age: see OVRO-LWA
- Large-Scale Polarization Explorer: see LSPE-STRIP
- Large-Scale Polarization Explorer: see LSPE-SWIPE
- Large-Scale Polarization Explorer/Short Wavelength Instrument for the Polarization Explorer (LSPE-SWIPE): plan for a balloon-based CMB polarization survey
- Large-Scale Polarization Explorer/Survey Tenerife Polarimeter (LSPE-STRIP): CMB survey telescope in Canary Islands
- Large-Sized Telescope: see Cherenkov Telescope Array
- LaRRI: see InSight
- LAS: see UKIDSS
- Las Campanas Observatory: observatory in southern Atacama Desert
- Las Campanas Redshift Survey: 1990s survey of galaxies out to z = 0.2
- Las Cumbres Observatory: world-wide network of telescopes
- Las Cumbres Observatory Global Telescope: see Las Cumbres Observatory
- LASCO: see Solar and Heliospheric Observatory
- LASCO C1: see Solar and Heliospheric Observatory
- LASCO C2: see Solar and Heliospheric Observatory
- LASCO C3: see Solar and Heliospheric Observatory
- LasDamas: simulations of large scale evolution of dark matter and galaxies
- laser: maser-like device for visible light
- laser com: laser communications
- adaptive optics: optical mechanism to compensate for varying atmospheric distortion
- laser guide star: see guide star
- adaptive optics: optical mechanism to compensate for varying atmospheric distortion
- laser gyroscope: see Sagnac effect
- Laser Interferometer Gravitational-wave Observatory (LIGO): pair of observatories to detect gravitational waves
- Laser Interferometer Space Antenna (LISA): proposed space mission to detect gravitational waves
- Laser Relativity Satellite (LARES): satellite to test a general relativity effect
- laser tomography AO: see adaptive optics
- lasercom (laser com): laser communications
- LaSilla QUEST Survey (LaSilla-QUEST Variability Survey): survey for transients
- LaSilla-QUEST Variability Survey: survey for transients
- LASMA: see Atacama Pathfinder Experiment
- LASS: see HEAO-1
- last parsec problem (final parsec problem): lack of a convincing theory on how SMBHs can reach each other
- last scattering surface (surface of last scattering): sphere around us from which CMB photons are just reaching us
- LAT: see Fermi
- LAT: see Simons Observatory
- Fermi bubbles: gamma-ray features associated with Milky Way center
- LAT All-sky Survey
- Fermi: satellite for studying gamma rays
- late: see spectral class
- late heavy bombardment: time after solar system planet-formation when many impacts occurred
- late thermal pulse: see thermal pulse
- late time anisotropies: see CMB anisotropies
- late-type galaxy: see galaxy
- late-type nitrogen-rich Wolf-Rayet: see Wolf-Rayet star
- late-type star: see spectral class
- latent heat
- Latest Supernovae: recent supernova info collected
- latitude
- circle of latitude: circle around the Earth of points equidistant from a pole or the equator
- lattice Boltzmann method: computational fluid dynamics method treating the fluid as particles
- Latysev: see rare designator prefixes
- LAU: see double star designation
- launch window: time period for launching space probes traveling a particular route
- lava planet: rocky planet with molten rock surface
- magma ocean: presumed to occur early in Earth history and potentially on exoplanets
- law of cosmic censorship: a singularity cannot be observed
- law of gravitation: see Newton's laws
- law of refraction (Snell's law): optical principle of refraction
- LAWD: see rare designator prefixes
- Lawrence Berkeley National Laboratory: US energy-related physics laboratory
- Lawrence Livermore National Laboratory: US science and technology laboratory
- Lawrence Lowell Telescope: see Lowell Observatory
- laws of black hole mechanics: see black hole thermodynamics
- laws of thermodynamics: see thermodynamics
- LAXPC: see AstroSat
- LB (Lyman break): abrupt change in galaxy spectrum at the Lyman series wavelength limit
- LB: see rare designator prefixes
- LB-1: binary star with evidence of a black hole
- LBA (Long Baseline Array): radio interferometer using Australian telescopes
- LBC: see Large Binocular Telescope
- LBCB: see Large Binocular Telescope
- LBCR: see Large Binocular Telescope
- LBDS: see rare designator prefixes
- LBG (Lyman-break galaxy): a galaxy emitting very little shorter than 912 angstroms
- LBG: see brightest cluster galaxy
- LBM (lattice Boltzmann method): computational fluid dynamics method treating the fluid as particles
- LBN (Lynds Catalogue of Bright Nebulae): 1950s/1960s list of bright nebulae found on Palomar plates
- LBNL (Lawrence Berkeley National Laboratory): US energy-related physics laboratory
- LBQS (Large Bright QSO Survey): 1980s quasar survey
- LBT (Large Binocular Telescope): dual 8.4 meter telescope in Arizona
- LBTI: see Large Binocular Telescope
- LBTI/LMIRCAM: see Large Binocular Telescope
- LBTI/NOMIC: see Large Binocular Telescope
- LBV (luminous blue variable): type of extremely bright variable stars
- LBV outburst: see luminous blue variable
- LC: see Coronal Solar Magnetism Observatory
- LCC: see Scorpius-Centaurus Association
- LCDCS: see rare designator prefixes
- LCDM (Lambda-CDM model): Big-Bang cosmological model with a cosmological constant and cold dark matter
- LCGT (KAGRA): gravitational wave detector in Japan preparing for operation
- LCL: see Lacaille Star Catalog
- LCO (Las Campanas Observatory): observatory in southern Atacama Desert
- LCO (Las Cumbres Observatory): world-wide network of telescopes
- LCOGT: see Las Cumbres Observatory
- LCROSS: space probe observing the lunar poles
- LCRS (Las Campanas Redshift Survey): 1990s survey of galaxies out to z = 0.2
- LCT (Caltech Submillimeter Observatory): 10.4 meter submillimeter telescope previously in Hawaii
- Atacama Desert: Chilean high-altitude, dry plateau with numerous observatories
- LD: see rare designator prefixes
- LDN (Lynds Catalog of Dark Nebulae): 1950s/1960s list of dark nebulae found on Palomar plates
- LDN 1527: dark nebula in Taurus
- LDN 1527 IRS: see LDN 1527
- LDN 1689: dense core within the Rho Ophiuchi Cloud Complex
- LDN 483 (L483): protostar of interest
- LDS (Luyten Double Star Survey): 1940s-1970s catalog of double stars
- LDSS3: see Magellan Telescopes
- LDT (Lowell Discovery Telescope): 4.3 m telescope at Lowell Observatory, Arizona
- Le Gentil: see rare designator prefixes
- lead star: see chemically peculiar star
- leakage neutron: see neutron scattering
- LEAP: see European Pulsar Timing Array
- leap day: see Julian calendar
- leap year: see sidereal
- learning
- LECP: see Voyager
- LECS: see BeppoSAX
- LED: see Small Astronomy Satellite 3
- LEDA: galaxy database with observation data
- LEDA: see OVRO-LWA
- LEDA: see Principal Galaxies Catalog
- LEDA 3097693: see NGC 1052
- LEDA 50779 (Circinus Galaxy): nearest Seyfert galaxy
- Lee-Weinberg argument: see Lee-Weinberg bound
- Lee-Weinberg bound: lower limit on mass of heavy lepton
- Lee-Weinberg limit (Lee-Weinberg bound): lower limit on mass of heavy lepton
- Lee-Weinberg window: see Lee-Weinberg bound
- left-hand circular polarization: see polarization
- Legacy Archive for Microwave Background Data Analysis (LAMBDA): NASA archive center re CMB data
- legacy survey: phrase sometimes used in survey names
- Legacy Survey of Space and Time: see Rubin Observatory
- LEGAS: see LAMOST
- Legendre polynomials: useful sequence of polynomials
- Lego principle: principle that life is associated with a skew in molecule abundances
- LEGUE: see LAMOST
- LEHPM: see rare designator prefixes
- LEIA: see Satech-01
- Leiden Atomic and Molecular Database: see RADEX
- LAMBDA: NASA archive center re CMB data
- Leiden Observatory
- Leighton Chajnantor Telescope (Caltech Submillimeter Observatory): 10.4 meter submillimeter telescope previously in Hawaii
- LEISA: see Lucy
- LEKID: see KID
- Lempo
- LENA: see IMAGE
- LEND: see Lunar Reconnaissance Orbiter
- length contraction: see Lorentz transformation
- lens: see gravitational lensing
- refraction: redirection of light passing from one medium to another
- refractive index: measure of how much a material slows down light
- Lense-Thirring effect: effect on precession from frame dragging
- LARES: satellite to test a general relativity effect
- Lense-Thirring precession (Lense-Thirring effect): effect on precession from frame dragging
- lensing deflection field: see CMB lensing
- lensing map: see CMB lensing
- lenslet array: see integral field spectrograph
- lenslet array: see integral field unit
- lensmaker's equation
- lensmaker's formula
- lenticular galaxy: disk galaxy that has no spirals
- LEO (low Earth orbit): Earth orbit within 2000 km of the surface
- LEO: see double star designation
- Leo Cluster
- Leo I
- Leo II
- Leo IV
- Leo T
- Leo V
- lepton: elementary particle with 1/2 integer spin such as electron
- lepton: see particle
- baryon: protons, neutrons, and other three-quark particles
- electron: type of lepton that is stable and has an electric charge of -1
- flavor: subtype of some type of particle
- positron: electron-like antimatter particle with electric charge of +1
- LESS (LABOCA Extended Chandra Deep Field-South Submillimetre Survey): submillimeter survey of a well-studied piece of sky
- LEST (Large Earth-based Solar Telescope): 1990s plan for 2.4 m solar telescope
- LETG: see Chandra X-ray Observatory
- LETGS: see Chandra X-ray Observatory
- Level 5: hyperlinked collection of astrophysics research findings
- Levy Spectrometer: see Automated Planet Finder
- LF (luminosity function): function giving number of stars or galaxies at different luminosities
- LF: see very low frequency
- LF radio astronomy (low frequency radio astronomy): astronomy using the lower end of the radio spectrum
- LFAA: see Square Kilometre Array
- LFAM: see rare designator prefixes
- LFC: see Hale Telescope
- LFI: see Planck
- LFT: see Luyten Half-second Catalog
- LFTO: see globular cluster luminosity function
- LG (Local Group): group of galaxies including the Milky Way
- LGA: see beam
- LGG: see rare designator prefixes
- LGGS (Local Group Galaxy Survey): photometric survey of stars in a number of local group galaxies
- LGM-1
- pulsar: type of astronomical body with EMR in regular cycles of seconds or less
- LGRB (long gamma-ray burst): GRB lasting more than two seconds
- LGRB: see gamma-ray burst
- LGRS: see GRAIL
- LGS: see guide star
- LGS: see rare designator prefixes
- adaptive optics: optical mechanism to compensate for varying atmospheric distortion
- LH: see rare designator prefixes
- LHA: see rare designator prefixes
- LHA 120-N 103B (N 103B): supernova remnant in the LMC
- LHAASO: gamma ray/cosmic ray observatory in China
- LHB (late heavy bombardment): time after solar system planet-formation when many impacts occurred
- LHC
- LHCP: see polarization
- LHEA (Laboratory for High Energy Astrophysics): former GSFC X-ray/gamma-ray lab of about 1970 to 2004
- LHG: see rare designator prefixes
- LHO: see LIGO
- LHO: see rare designator prefixes
- LHS (Luyten Half-second Catalog): 1979 catalog of 4000 stars with high proper motion
- LHS 1140: red dwarf with rocky planet in its habitable zone
- LHS 1140 b: see LHS 1140
- LHS 3844: see LHS 3844 b
- LHS 3844 b: rocky planet in habitable zone of a red dwarf
- LI: see IRAS
- Li (lithium): metal, Li, atomic number 3
- libration: oscillating motion of orbiting bodies relative to each other
- libration in latitude: see libration
- libration in longitude: see libration
- libration point (Lagrangian point): points around two orbiting bodies where small objects can sit
- libration point: see libration
- LIBS: see MMX
- LIC (Local Interstellar Cloud): local ISM region with slightly higher density of hydrogen
- LIC: see Local Bubble
- Lick indices: defined set of spectral line indexes for stars
- Lick Observatory: California observatory of long standing
- Lick Observatory and Tenagra Observatory Supernova Searches
- Lick Observatory Calcium Line Survey: 1980s survey of T-Tauri stars in the Taurus-Auriga Complex
- Lick Observatory Supernova Search: search for supernovae for cosmological study
- LID: see LAMOST
- LIDAR: see Hayabusa2
- LIDAR: see MMX
- LIDAR: see Mars Polar Lander
- Lidov-Kozai effect (Kozai mechanism): an effect on an orbit by another, more distant orbiting body
- Lidov-Kozai mechanism (Kozai mechanism): an effect on an orbit by another, more distant orbiting body
- Lie algebra: see Lie transform
- Lie group: see Lie transform
- Lie transform: type of infinitesimal transform
- Lie transformation (Lie transform): type of infinitesimal transform
- life
- lifetime: see e-folding time
- light (visible light): electromagnetic radiation that our eyes can sense
- light amplification by stimulated emission of radiation: see maser
- light cone: region of space-time which you can see or can see you
- Light Curve
- light curve: changing intensity of light from a transient
- light curves
- GERLUMPH: hardware/software simulator of lensing light curves
- Sys-Rem: algorithm to remove systematics from light curve data
- light cylinder
- light dark matter (sub-GeV dark matter): a more-massive type of CDM
- light echo: reflected light from an astronomical event arriving later
- dust echo: the glow of dust heated by a transient
- light nebula
- cloud: higher-density region of space
- light neutrino: see neutrino
- light pollution: light from cities that interferes with astronomical observation
- Light satellite for the studies of B-mode polarization and inflation from cosmic background radiation detection (LiteBIRD): planned spacecraft to map CMB polarization
- light speed (speed of light): fundamental constant measured as the speed at which light travels
- light's speed (speed of light): fundamental constant measured as the speed at which light travels
- light-year: distance that light travels in a year
- parsec: about 3.26 light-years
- lightcurve
- lightest supersymmetric particle: see supersymmetry
- lightkurve: software to analyze time series data
- LIGO: pair of observatories to detect gravitational waves
- LIGO A#Observing Run 4: see LIGO
- LIGO A+: see LIGO
- LIGO H: see LIGO
- LIGO Hanford Observatory: see LIGO
- LIGO L: see LIGO
- LIGO Livingston Observatory: see LIGO
- LIGO Voyager: see LIGO
- LIGO-India: planned gravitational wave detector in India
- likelihood
- likelihood distribution
- LIM: see intensity mapping
- limb: the edge of an astronomical object as viewed
- limb: see limb darkening
- limb darkening: the darkening of edge of a body such as the Sun
- limb: the edge of an astronomical object as viewed
- transiting planet: planet crossing between another body and the observer
- Limber approximation: formula approximating the density of galaxies in some direction
- Limber equation (Limber approximation): formula approximating the density of galaxies in some direction
- Limber formula (Limber approximation): formula approximating the density of galaxies in some direction
- limit: see series expansion
- limiting magnitude: faintest magnitude that a telescope or instrument can detect
- LIN: see rare designator prefixes
- LINC/Nirvana: see Large Binocular Telescope
- Lincoln Laboratory
- LINEAR: survey of near-Earth objects
- Lincoln Near-Earth Asteroid Research (LINEAR): survey of near-Earth objects
- Lindblad resonance: resonant orbits within a disk due to a high-density portion
- Lindblad resonance: see Lindblad torque
- Lindblad torque: torque due to Lindblad resonances
- Lindsay: see rare designator prefixes
- line (spectral line): dark or bright line in a spectrum
- line blanketing: so many bunched spectral lines that they cannot be distinguished
- CMFGEN: RT code designed to handle significant stellar wind
- line broadening: processes causing a spectral line to have width
- line broadening function
- line depth: see line broadening
- line index: see spectral line designation
- line intensity mapping: see intensity mapping
- line of beta stability (valley of beta stability): set of isotopes not prone to beta decay
- line of nodes: see orbital element
- line of sight: line between observer and observed object
- line profile (spectral line shape): yields information about source
- line profile: see line shape function
- line series
- line shape (spectral line shape): yields information about source
- line shape: see line shape function
- line shape function: function describing the shape of a spectral line
- line tomography: using double-peaked spectral lines to place constituents of a disk
- line-blanketing effect (line blanketing): so many bunched spectral lines that they cannot be distinguished
- line-of-sight (line of sight): line between observer and observed object
- line-of-sight velocity (radial velocity): component of velocity toward or away from observer
- LINEAR: survey of near-Earth objects
- linear algebra
- linear GW memory: see gravitational-wave memory
- linear polarization: see polarization
- linear system: see linear theory
- linear theory: theory of operators satisfying the property of superposition
- linear variable filter (linearly variable filter): filter whose passband varies over one spatial dimension
- linearly variable filter: filter whose passband varies over one spatial dimension
- SPHEREx: all-sky spectral survey space-mission plan
- LINER: galaxy nucleus emitting spectral lines for ionized and neutral atoms
- LINER galaxy: see LINER
- lines
- lipids
- Lego principle: principle that life is associated with a skew in molecule abundances
- liquid mirror: see liquid mirror telescope
- liquid mirror telescope: reflector telescope with primary mirror formed of spinning liquid
- liquid planet: planet consisting of liquid
- liquid water habitable zone: see habitable zone
- liquid water zone: see habitable zone
- LIR: see infrared
- LIRG (luminous infrared galaxy): a galaxy emitting a lot of far-infrared light
- LIRIC: see Liverpool Telescope
- LIRIS: see William Herschel Telescope
- LISA: proposed space mission to detect gravitational waves
- LISA Pathfinder: see LISA
- Lissajous orbit: see halo orbit
- LiteBIRD: planned spacecraft to map CMB polarization
- lithium: metal, Li, atomic number 3
- lithium burning: any fusion reaction starting with lithium
- lithosphere
- lithospheric flexure: see elastic thickness
- Little Ice Age
- Littrow: see grating
- Livermore Optical Transient Imaging System: automated telescope aiming to catch GRB optical counterparts
- Liverpool John Moores University
- Liverpool Telescope: 2-meter robotic telescope in Spain
- Liverpool Telescope 2: see Liverpool Telescope
- LK oscillation: see Kozai mechanism
- LkCa: see rare designator prefixes
- LkCl (Lick Observatory Calcium Line Survey): 1980s survey of T-Tauri stars in the Taurus-Auriga Complex
- LkHA: see rare designator prefixes
- LLAGN: see active galactic nucleus
- Llano de Chajnantor Observatory: group of observatories on a high plateau of the Atacama Desert
- LLNL (Lawrence Livermore National Laboratory): US science and technology laboratory
- LLO: see LIGO
- LM: see rare designator prefixes
- lm plane: see u-v plane
- LMAG: see SELENE
- LMC (Large Magellanic Cloud): somewhat irregular satellite galaxy of the Milky Way
- LMC: see Rosalind Franklin
- LMC AB: see rare designator prefixes
- LMC-N: see rare designator prefixes
- LMI: see Lowell Discovery Telescope
- LMIRCAM: see Large Binocular Telescope
- LMPO: see protostar
- LMS (low mass star): star with less than half a solar mass
- LMT (Large Millimeter Telescope): large microwave telescope in Mexico
- TolTEC: sensitive infrared camera under construction for the LMT
- LMXB: see X-ray binary
- Ln (lanthanide): element having atomic number within 57 through 71
- LN2 (LN2): "liquid nitrogen"
- LN2: "liquid nitrogen"
- LNA (low noise amplifier): amplifier aimed at very low noise for extremely sensitive measurement
- LNRF (ZAMO frame): a frame of reference that is not rotating
- LO: see beat frequency
- Lo: see rare designator prefixes
- load density: measure of rigidity of the crust of a body
- LOAN: see orbital element
- lobe: see beam
- lobe: see radio galaxy
- local
- Local Arm: see spiral arm
- local BHMF: see black hole mass function
- local black hole mass function: see black hole mass function
- Local Bubble: ISM shell in which the solar system resides
- Local Cavity (Local Bubble): ISM shell in which the solar system resides
- local flow: see Hubble expansion
- Local Fluff (Local Interstellar Cloud): local ISM region with slightly higher density of hydrogen
- Local Fluff: see Local Bubble
- Local Group: group of galaxies including the Milky Way
- Local Group Galaxy Survey: photometric survey of stars in a number of local group galaxies
- Local Interstellar Cloud: local ISM region with slightly higher density of hydrogen
- Local Interstellar Cloud: see Local Bubble
- local merger: see galaxy merger
- local meridian: see meridian
- meridian circle: instrument for timing the passage of stars over a meridian
- local noon: time at a locality when the Sun is at its highest
- local oscillator: see beat frequency
- Local Sheet: flat grouping of galaxies around the Local Group
- local sidereal time: same as angular hours right ascension of the zenith
- local standard of rest: velocity with respect to our region of the Milky Way
- Local Supercluster (Laniakea Supercluster): group of clusters including the Local Group
- Local Supercluster (Virgo Supercluster): supercluster including the Local Group
- local thermodynamic equilibrium: state when temperature variation is too small to matter
- Local Void: void next to the Local Group
- Local Volume: region around the Local Group
- Local Volume Mapper: see Sloan Digital Sky Survey
- localization: ability to identify location of a transient
- locally brightest galaxy: see brightest cluster galaxy
- locally non-rotating frame (ZAMO frame): a frame of reference that is not rotating
- location
- Lock-In Amplified Externally Dispersed Interferometry: technique for precise RV measurement
- Lockman Cloud (Smith Cloud): high-velocity cloud on collision course with Milky Way
- Lockman hole: region of sky with little Milky-Way neutral hydrogen
- LOFAR (Low-frequency Array): low frequency radio telescope
- LOFAR Prototype Station (LOPES): cosmic ray detector that detected resulting radio
- LOFAR Two-metre Sky Survey
- LOFAR-core
- log ε(O): see metallicity
- log frequency: see low frequency radio astronomy
- log g: see surface gravity
- log-log plot: see power law
- logarithmic
- LOLA: see Lunar Reconnaissance Orbiter
- LONEOS: survey of near-Earth objects
- Long Baseline Array: radio interferometer using Australian telescopes
- long gamma-ray burst: GRB lasting more than two seconds
- long gamma-ray burst: see gamma-ray burst
- long pass: see filter designator
- long period variable: see variable star
- long Rossby wave: see Kelvin waves
- Long Wavelength Array: radio telescope in New Mexico
- long-duration gamma-ray burst (long gamma-ray burst): GRB lasting more than two seconds
- long-duration GRB (long gamma-ray burst): GRB lasting more than two seconds
- long-period B-star (slowly-pulsating B-star): B-star with pulsation periods of more than half a day
- long-period comet: comet with an orbital period of more than 200 years
- Oort Cloud: cloud of distant comets surrounding the solar system
- long-period comets
- longitude of ascending node: see orbital element
- lookback time: see cosmic time
- Loop I Bubble: see Local Bubble
- loose group: see galaxy group
- LOPES: cosmic ray detector that detected resulting radio
- Lorentz drag
- Lorentz factor: see Lorentz transformation
- Lorentz force: force on a point charge due to magnetic fields
- Lorentz invariance (relativistic invariance): quantity that remains the same regardless of frame of reference
- Lorentz transform (Lorentz transformation): equations describing the effect of relative motion on length and velocity
- Lorentz transformation: equations describing the effect of relative motion on length and velocity
- cosmological redshift: redshift of distant objects due to the Hubble expansion
- redshift: change to longer wavelengths due to Doppler effects
- spacetime: four dimensions: time and the three space dimensions
- Lorentzian distribution: probability distribution applicable to some physics phenomena
- damping profile: mathematical shape that models some types of spectral line broadening
- Lorentzian function: see Lorentzian distribution
- Lorentzian profile (damping profile): mathematical shape that models some types of spectral line broadening
- Lorenz transform: see relativity
- Lorimer burst: see fast radio burst
- LORRI: see New Horizons
- LOS (line of sight): line between observer and observed object
- Los Alamos Computational Astrophysics Simulation Suite (LA-COMPASS): MHD-capable hydrodynamic code
- Los Alamos National Laboratory
- LOS velocity (radial velocity): component of velocity toward or away from observer
- LOSS (Lick Observatory Supernova Search): search for supernovae for cosmological study
- loss cone: see final parsec problem
- LOSVD: line-of-sight velocity distribution
- LOTIS (Livermore Optical Transient Imaging System): automated telescope aiming to catch GRB optical counterparts
- LOTOSS
- LoTr: see rare designator prefixes
- LoTSS
- LOUVOIR-A (High Definition Space Telescope): proposed 12 m space telescope
- LOV (Tolman-Oppenheimer-Volkoff limit): maximum mass of a neutron star
- Love number: measures of rigidity of a body
- Love-Shida number (Love number): measures of rigidity of a body
- Lovell Telescope: see Jodrell Bank Observatory
- Lovell Transit Telescope
- Lovelock gravity: generalization of general relativity
- Lovelock theory of gravity (Lovelock gravity): generalization of general relativity
- low Earth orbit: Earth orbit within 2000 km of the surface
- Low Frequency: see very low frequency
- low frequency
- Low Frequency Aperture Array: see Square Kilometre Array
- low frequency radio astronomy: astronomy using the lower end of the radio spectrum
- low frequency radio astronomy: see radio astronomy
- low gain antenna: see beam
- low mass star: star with less than half a solar mass
- low noise amplifier: amplifier aimed at very low noise for extremely sensitive measurement
- low redshift: see cosmological redshift
- low resolution spectrograph: see HRS
- low resolution spectrography: see HRS
- low surface gravity: see surface gravity
- low-alpha: see alpha-enhanced
- Low-frequency Array: low frequency radio telescope
- low-ionization nuclear emission-line region (LINER): galaxy nucleus emitting spectral lines for ionized and neutral atoms
- low-mass protostellar object: see protostar
- low-mass X-ray binary: see X-ray binary
- low-surface-brightness galaxy: galaxies less bright than those historically identified
- low-velocity cloud: see high-velocity cloud
- Lowell Discovery Telescope: 4.3 m telescope at Lowell Observatory, Arizona
- Lowell Observatory: Arizona observatory of long standing
- Lowell Observatory Near-Earth-object Search (LONEOS): survey of near-Earth objects
- Lowell Proper Motion Survey: 1950s-1970s catalogs of stars with proper motion
- Lower Centaurus-Crux: see Scorpius-Centaurus Association
- lower meridian: see celestial meridian
- lower meridian: see meridian
- lowmass star (low mass star): star with less than half a solar mass
- LOWZ North 13788 void
- void: empty spaces between large scale structures
- LP (Langmuir probe): plasma sensor
- LP (Luyten Palomar Survey): 1970s catalog of stars with high proper motion
- LP: see NIRSpec
- LP: see filter designator
- LP: see rare designator prefixes
- LPB (slowly-pulsating B-star): B-star with pulsation periods of more than half a day
- LPI (Lunar and Planetary Institute): scientific research arm of USRA
- LPL (Lunary and Planetary Laboratory): U Arizona lab
- LPM: see Bruce Proper Motion Survey
- LPO (La Silla Paranal Observatory): manages three ESO observatory-sites in Chile
- LPO (Roque de los Muchachos Observatory): observatory at La Palma in the Canary Islands
- LPO: see double star designation
- LPR: for "light pollution reduction"
- LPR: see filter designator
- LPV: see MAVEN
- LPV: see variable star
- LQG (large quasar group): structure consisting of a collection of quasars
- Huge-LQG: possible overly-large structure
- LRG (luminous red galaxy): distant bright red galaxies in the Sloan Digital Sky Survey
- LRIS: see Keck Observatory
- LRN (luminous red nova): red-colored event theorized to be a merger of two stars
- LRO (Lunar Reconnaissance Orbiter): space probe orbiting the Moon
- LROC: see Lunar Reconnaissance Orbiter
- LRS: see HRS
- LRS: see Hobby-Eberly Telescope
- LRS: see IRAS
- LRS: see SELENE
- LRS2: see Hobby-Eberly Telescope
- LS (Case-Hamburg Survey): 1950s-1970s survey(s) of OB stars
- LS (Virgo Supercluster): supercluster including the Local Group
- LS 2883: see PSR B1259-63
- LS V +22 25 (LB-1): binary star with evidence of a black hole
- LSB: see rare designator prefixes
- LSB galaxy (low-surface-brightness galaxy): galaxies less bright than those historically identified
- LSC (Virgo Supercluster): supercluster including the Local Group
- LSE: see Case-Hamburg Survey
- LSG
- LSO (La Silla Observatory): Atacama-desert observatory run by ESO
- LSP: see supersymmetry
- LSPE: see LSPE-STRIP
- LSPE: see LSPE-SWIPE
- LSPE-STRIP: CMB survey telescope in Canary Islands
- LSPE-SWIPE: plan for a balloon-based CMB polarization survey
- LSPM (Lépine Shara Proper Motion catalog): 2000s catalog of stars with proper motion
- LSQ (LaSilla-QUEST Variability Survey): survey for transients
- LSR (local standard of rest): velocity with respect to our region of the Milky Way
- LSR: see rare designator prefixes
- LSR velocity: see local standard of rest
- LSS (large scale structure): the universe's structure as in placement of clusters
- LSS: see Case-Hamburg Survey
- LSST (Rubin Observatory): 8-meter survey reflector telescope under construction in Chile
- LST (Large Submillimeter Telescope): concept for a 50-meter submillimeter telescope in Chile
- LST (local sidereal time): same as angular hours right ascension of the zenith
- LST: see Cherenkov Telescope Array
- LST1: see Cherenkov Telescope Array
- Lsun (solar luminosity): luminosity unit representing the luminosity of the Sun
- Sun: star at center of solar system
- LT (Liverpool Telescope): 2-meter robotic telescope in Spain
- LT: see rare designator prefixes
- LT2: see Liverpool Telescope
- LTE (local thermodynamic equilibrium): state when temperature variation is too small to matter
- LTG: see galaxy
- LTMO: see adaptive optics
- LTP (lunar transient phenomenon): observed transient on the Moon such as a flash of light
- LTP: see thermal pulse
- LTT (Luyten Two-Tenths Arcsecond Catalog): 1960 catalog of 9000+ stars with proper motion
- LUCI: see Large Binocular Telescope
- LUCI1: see Large Binocular Telescope
- LUCI2: see Large Binocular Telescope
- LUCIFER: see Large Binocular Telescope
- lucky exposures (lucky imaging): method of combining short-term images to yield better resolution
- Lucky imaging
- speckle imaging: method of combining short-term images to yield better resolution
- lucky imaging: method of combining short-term images to yield better resolution
- Lucy: space probe to observe Jupiter Trojan asteroids
- Luhman: see rare designator prefixes
- Luhman 16: nearby binary brown dwarf
- Luhman 16AB (Luhman 16): nearby binary brown dwarf
- luminescence: see fluorescence
- luminosity: measure of brightness
- luminosity (bolometric luminosity): total luminosity of an object at all wavelengths
- luminosity class: classification of size/luminosity of stars
- subgiant: slightly larger than normal star
- luminosity density: luminosity per unit volume
- luminosity distance: distance to an object based upon the distance's effect on received flux
- luminosity equation: see stellar structure
- luminosity function: function giving number of stars or galaxies at different luminosities
- luminosity function: see sensitivity function
- luminosity function turnover: see globular cluster luminosity function
- luminosity-decline rate relation
- luminous blue variable: type of extremely bright variable stars
- luminous infrared galaxy: a galaxy emitting a lot of far-infrared light
- luminous red galaxy: distant bright red galaxies in the Sloan Digital Sky Survey
- luminous red nova: red-colored event theorized to be a merger of two stars
- luminous supergiant: see supergiant
- lumped element KID: see KID
- Lunar and Planetary Institute: scientific research arm of USRA
- lunar cold trap
- moon: a planet's natural satellite, such as Earth's
- Lunar Crater Observation and Sensing Satellite (LCROSS): space probe observing the lunar poles
- lunar eclipse: see solar eclipse
- Lunar Prospector: NASA 1998 lunar orbiter
- Lunar Reconnaissance Orbiter: space probe orbiting the Moon
- Lunar Surface Gravimeter
- lunar swirl: swirly spot on the surface of the Moon
- lunar transient phenomenon: observed transient on the Moon such as a flash of light
- lunar water: water on the moon
- Lunar-based Ultraviolet Telescope: Chinese ultraviolet telescope on the Moon
- Lunary and Planetary Laboratory: U Arizona lab
- Lund: see Lund Catalogue of Open Clusters
- Lund Catalogue of Open Clusters: list of open clusters
- Lund Observatory
- Lupus: see Lupus Transit Survey
- Lupus Transit Survey: survey for hot Jupiters in a region of constellation Lupus
- LUT (Lunar-based Ultraviolet Telescope): Chinese ultraviolet telescope on the Moon
- Lutz-Kelker bias: measurement bias due to unbalanced parallax uncertainties
- LUVOIR: plan for a space-based telescope
- LUVOIR-A: see LUVOIR
- LUVOIR-B: see LUVOIR
- LUX: experiment to identify WIMPs with a tank of xenon
- LUX: see ZEPLIN
- LUX-ZEPLIN: see LUX
- LUX-ZEPLIN: see ZEPLIN
- LUY: see double star designation
- Luyten 726-8: nearby binary star system
- Luyten Double Star Survey: 1940s-1970s catalog of double stars
- Luyten Five Tenths Catalog: see Luyten Half-second Catalog
- Luyten Half-second Catalog: 1979 catalog of 4000 stars with high proper motion
- Luyten Palomar Survey: 1970s catalog of stars with high proper motion
- Luyten Two-Tenths Arcsecond Catalog: 1960 catalog of 9000+ stars with proper motion
- LV (Local Volume): region around the Local Group
- LVC: see high-velocity cloud
- LVF (linearly variable filter): filter whose passband varies over one spatial dimension
- LVM: see Sloan Digital Sky Survey
- LW: see rare designator prefixes
- LW flux: see Lyman-Werner photon
- LW radiation: see Lyman-Werner photon
- LWA (Long Wavelength Array): radio telescope in New Mexico
- LWA1: see Long Wavelength Array
- LWCam: see CCAT
- LWP: see International Ultraviolet Explorer
- LWR: see International Ultraviolet Explorer
- LWS: see Infrared Space Observatory
- LWS: see International Ultraviolet Explorer
- LWS: see Keck Observatory
- LXM: see Lynx
- Ly (Lyman series): hydrogen series from electrons settling from n > 1 to n = 1
- Ly: see rare designator prefixes
- ly (light-year): distance that light travels in a year
- Ly continuum (Lyman continuum): absorption continuum beginning at Lyman limit
- Lyα (Lyman alpha): first line in the Lyman series
- Lyβ (Lyman beta): second line in the Lyman series
- Ly-α (Lyman alpha): first line in the Lyman series
- Lyman series: hydrogen series from electrons settling from n > 1 to n = 1
- Ly-α forest (Lyman-alpha forest): overlaid redshifted Lyman-alpha absorption lines on light from distant objects
- Ly-β (Lyman beta): second line in the Lyman series
- Ly-β: see Lyman series
- Lyapunov exponent
- Lyapunov time: timescale beyond which a dynamical system is chaotic
- Lyapunov orbit: see halo orbit
- Lyapunov time: timescale beyond which a dynamical system is chaotic
- LyC (Lyman continuum): absorption continuum beginning at Lyman limit
- LyC escape: see Lyman continuum
- LyC escape: see Lyman series
- LyC leaker: see Lyman continuum
- LyC leaker: see Lyman series
- LyC photon: see Lyman continuum
- LyC photons: see Lyman series
- Lyman
- Lyman α (Lyman alpha): first line in the Lyman series
- Lyman β (Lyman beta): second line in the Lyman series
- Lyman alpha: first line in the Lyman series
- Lyman band: see Lyman-Werner photon
- Lyman beta: second line in the Lyman series
- Lyman beta: see Lyman series
- Lyman break: abrupt change in galaxy spectrum at the Lyman series wavelength limit
- Lyman continuum: absorption continuum beginning at Lyman limit
- continuum: portion of a continuous spectrum not affected by a spectral feature
- Lyman continuum escape: see Lyman continuum
- Lyman continuum escape: see Lyman series
- Lyman continuum leaker: see Lyman continuum
- Lyman continuum leaker: see Lyman series
- Lyman continuum photon: see Lyman continuum
- Lyman continuum photons: see Lyman series
- Lyman cutoff (Lyman break): abrupt change in galaxy spectrum at the Lyman series wavelength limit
- Lyman edge (Lyman break): abrupt change in galaxy spectrum at the Lyman series wavelength limit
- Lyman jump (Lyman break): abrupt change in galaxy spectrum at the Lyman series wavelength limit
- Balmer jump: abrupt change in stellar spectrum at the Balmer series wavelength limit
- Lyman limit: see Lyman series
- Lyman break: abrupt change in galaxy spectrum at the Lyman series wavelength limit
- Lyman continuum: absorption continuum beginning at Lyman limit
- Lyman-break galaxy: a galaxy emitting very little shorter than 912 angstroms
- Lyman lines (Lyman series): hydrogen series from electrons settling from n > 1 to n = 1
- Lyman series: hydrogen series from electrons settling from n > 1 to n = 1
- hydrogen: most prominent element, atomic number 1
- Lyman break: abrupt change in galaxy spectrum at the Lyman series wavelength limit
- Lyman continuum: absorption continuum beginning at Lyman limit
- Lyman-alpha emitter: redshifted galaxy emitting the Lyman alpha line
- Lyman-alpha forest: overlaid redshifted Lyman-alpha absorption lines on light from distant objects
- Lyman-alpha blob: Lyman-alpha emitting cloud larger than a galaxy
- Lyman-alpha break: see Lyman break
- Lyman-alpha emitter: redshifted galaxy emitting the Lyman alpha line
- GLARE: project to search for distant star-forming galaxies
- Lyman-alpha emitting galaxy (Lyman-alpha emitter): redshifted galaxy emitting the Lyman alpha line
- Lyman-alpha forest: overlaid redshifted Lyman-alpha absorption lines on light from distant objects
- Lyman-beta forest: see Lyman-alpha forest
- Lyman-break galaxy: a galaxy emitting very little shorter than 912 angstroms
- Lyman-Werner background: see Lyman-Werner photon
- Lyman-Werner flux: see Lyman-Werner photon
- Lyman-Werner photon: ultraviolet photon with proper energy to excite molecular hydrogen
- Lyman-Werner radiation: see Lyman-Werner photon
- Lynden-Bell mechanism: a model for galaxy bar formation
- Lynds 1689 (LDN 1689): dense core within the Rho Ophiuchi Cloud Complex
- Lynds Catalog of Dark Nebulae: 1950s/1960s list of dark nebulae found on Palomar plates
- LDN 1689: dense core within the Rho Ophiuchi Cloud Complex
- Lynds Catalogue of Bright Nebulae: 1950s/1960s list of bright nebulae found on Palomar plates
- Lynx: concept for space X-ray observatory
- Lynx X-ray Observatory (Lynx): concept for space X-ray observatory
- Lynx-Ursa Major Filament: see galaxy filament
- Lyon Observatory
- Lyon-Meudon Extragalactic Database (LEDA): galaxy database with observation data
- Lyon-Meudon Extragalactic Database: see Principal Galaxies Catalog
- Lyot coronagraph: original coronagraph design
- Lyot filter
- Lyot stop: optical element to block unwanted light within instruments
- LZ: see ZEPLIN
- LZT (Large Zenith Telescope): 6 meter liquid mirror telescope in British Columbia
Index