Term Index (C)

Astrophysics (Index)

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Term Index (C)

Astrophysical terms and names of things beginning with the letter C.

C1 C2 CA CB CC CD CE CF CG CH CI CK CL CM CN CO CP CR CS CT CU CV CW CX CY CZ

C (Cambridge Catalog of Radio Sources): series of catalogs of northern hemisphere sources
C (carbon star): star with more carbon than oxygen in its atmosphere
C (carbon): element, C, atomic number 6
C: see Caldwell Catalog
C: see filter designator
C: see rare designator prefixes
c (speed of light): fundamental constant measured as the speed at which light travels
c: see relativity
- refraction: redirection of light passing from one medium to another
- refractive index: measure of how much a material slows down light
C band: see C-BASS
C chondrite (carbonaceous chondrite): stony meteorites with carbon compounds showing no melting
C class: see carbon star
C*: see rare designator prefixes
CνB (cosmic neutrino background): low-energy neutrinos left over from early universe
- cosmic background radiation: electromagnetic radiation coming from every direction
Côte d'Azur Observatory: French astronomical research organization
C-Band All Sky Survey (C-BASS): 6 cm survey of the entire sky
C-band All Sky Survey

Owens Valley Radio Observatory: group of radio telescopes in California near the VLBA

C-BASS: 6 cm survey of the entire sky
C-BASS Telescope

Owens Valley Radio Observatory: group of radio telescopes in California near the VLBA

C-COSMOS: see Cosmic Evolution Survey
C-H (methylidyne): compound of one carbon and one hydrogen atom
C-type shock: see shock wave
C-type star (carbon star): star with more carbon than oxygen in its atmosphere
C. Donald Shane Telescope (Shane Telescope): 3.05 m reflector telescope at Lick Observatory
C/2014 UN₂₇₁: very large comet discovered at a distance
C/2017 U1 (Oumuamua): small body that passed through the solar system in 2017
C/P: see Solar Maximum Mission
C12(α,γ)O16 reaction: see triple alpha process
C2PU: see GI2T
C₂₀: see gravitational potential model
C₂₂: see gravitational potential model
C₂H₂ (acetylene): compound of two carbon and two hydrogen atoms
C₂H₄ (ethylene): compound of two carbon and four hydrogen atoms
C₃H₄

tracer: chemical whose detection indicates the presence of something else

C₆₀: see polycyclic aromatic hydrocarbon
- diffuse interstellar bands: type of absorption bands seen in astronomical objects
C_P: see specific heat
C_V: see specific heat
C⁺: ionized carbon missing one electron
- carbon: element, C, atomic number 6
C¹⁷O: see carbon monoxide
C¹⁸O: see carbon monoxide
Ca (calcium): element, Ca, atomic number 20
Ca I

calcium: element, Ca, atomic number 20

Ca II

calcium: element, Ca, atomic number 20

Ca II K line: see Wilson-Bappu effect
ca-rich gap transient (calcium-rich gap transient): type of explosive event larger than a nova and smaller than a supernova
ca-rich supernova (calcium-rich gap transient): type of explosive event larger than a nova and smaller than a supernova
ca-rich transient (calcium-rich gap transient): type of explosive event larger than a nova and smaller than a supernova
CADC (Canadian Astronomy Data Centre): online data distribution
cadence: period between observations
CAESAR: planned space mission to return a sample of a comet
CAHA (Centro Astronómico Hispano-Alemán): German-Spanish Astronomical Center at Calar Alto.
CAI: calcium/aluminum specs in chondrites
CAIRNS: see rare designator prefixes
CAL: see rare designator prefixes
Calán/Tololo Supernova Search (Calán/Tololo Supernova Survey): late 1980s to early 1990s search to redshift 0.1
Calán/Tololo Supernova Survey: late 1980s to early 1990s search to redshift 0.1
Calán/Tololo Survey (Calán/Tololo Supernova Survey): late 1980s to early 1990s search to redshift 0.1
Calar: see rare designator prefixes
Calar Alto

Calar Alto Observatory: observatory on mountain in mainland Spain

Calar Alto 2.2 meter telescope

Munich Near-Infrared Cluster Survey: 1990s-2000s galaxy cluster survey

Calar Alto 3.5 Meter Telescope

CALIFA: spectroscopic map of 600 galaxies

Calar Alto 3.5 meter telescope

Munich Near-Infrared Cluster Survey: 1990s-2000s galaxy cluster survey

Calar Alto Legacy Integral Field Area Survey (CALIFA): spectroscopic map of 600 galaxies
Calar Alto Observatory: observatory on mountain in mainland Spain
- CALIFA: spectroscopic map of 600 galaxies
- Munich Near-Infrared Cluster Survey: 1990s-2000s galaxy cluster survey
calcium: element, Ca, atomic number 20
- Am star: A-type star with metallic lines
- HK Survey: 1985 search for metal poor-stars using calcium lines
calcium carbonate

carbonate-silicate cycle: long-term cycle that sequesters Earth carbon
silicate weathering feedback: feedback mechanism stabilizing carbon in Earth atmosphere

calcium silicate

carbonate-silicate cycle: long-term cycle that sequesters Earth carbon
silicate weathering feedback: feedback mechanism stabilizing carbon in Earth atmosphere

calcium-aluminum-rich inclusion (CAI): calcium/aluminum specs in chondrites
calcium-rich gap transient: type of explosive event larger than a nova and smaller than a supernova
calcium-rich supernova (calcium-rich gap transient): type of explosive event larger than a nova and smaller than a supernova
calcium-rich transient (calcium-rich gap transient): type of explosive event larger than a nova and smaller than a supernova
Caldwell: see Caldwell Catalog
Caldwell 12 (NGC 6946): face-on spiral galaxy
Caldwell 30 (NGC 7331): spiral galaxy without a bar
Caldwell 5 (IC 342): spiral galaxy in the Council of Giants
Caldwell 74 (NGC 3132): PN of interest in southern sky
Caldwell 77 (Centaurus A): nearby radio galaxy
Caldwell 79 (NGC 3201): globular cluster in which a black hole has been identified
Caldwell Catalog: small catalog for amateur astronomers as an adjunct to the Messier Catalog
Calibrating Lyman-α with Hα: see X-SHOOTER Lyman α survey at z = 2
calibrator: see ALMACAL
CALIFA: spectroscopic map of 600 galaxies
California

Allen Telescope Array: array of radio telescopes in northern California for SETI
Armstrong Flight Research Center: NASA aeronautical research center in California
Automated Planet Finder: robotic telescope to find exoplanets using RV method
Big Bear Solar Observatory: US government sponsored solar observatory
BIMA telescope: millimeter interferometer in operation 1985 to 2005
California Association for Research in Astronomy: nonprofit aimed at operating Keck observatory
CHARA: optical interferometer on Mount Wilson
COMAP: high frequency radio telescope to map CO
Combined Array for Research in Millimeter-wave Astronomy: former array of radio telescopes in eastern California
Hale Telescope: 5.1 m reflector telescope in California
Hat Creek Radio Observatory: California observatory with the Allen Telescope Array
Lick Observatory: California observatory of long standing
Lick Observatory Supernova Search: search for supernovae for cosmological study
Livermore Optical Transient Imaging System: automated telescope aiming to catch GRB optical counterparts
Mount Wilson Observatory: Los Angeles observatory with Hooker telescope
OVRO-LWA: radio telescope in California
Owens Valley Radio Observatory: group of radio telescopes in California near the VLBA
Palomar 48 Inch Telescope: 48 inch Schmidt telescope at Palomar Observatory
Palomar 60-inch Telescope: 60 inch telescope at Palomar Observatory
Palomar Observatory: California observatory with Hale telescope
Palomar Testbed Interferometer: near-infrared interferometer experiment
Shane Telescope: 3.05 m reflector telescope at Lick Observatory
Sunyaev-Zel'dovich Array: array of eight 3.5 meter microwave telescopes
Table Mountain Observatory: NASA observatory near Los Angeles

California Association for Research in Astronomy: nonprofit aimed at operating Keck observatory
California Extremely Large Telescope: concept for an extremely large telescope
California-Kepler Survey: follow-up to Kepler to determine stellar radii
Callisto: well-known Jupiter moon
calorie: see energy
calorimeter: see microcalorimeter
CalTech

Palomar Observatory: California observatory with Hale telescope

Caltech

IPAC: Caltech group to collect and analyze infrared observations
Owens Valley Radio Observatory: group of radio telescopes in California near the VLBA
Two Micron Sky Survey: 1969 infrared catalog produced by Caltech

Caltech Infrared Catalog (Two Micron Sky Survey): 1969 infrared catalog produced by Caltech
Caltech Submillimeter Observatory: 10.4 meter submillimeter telescope previously in Hawaii
CALYMHA: see X-SHOOTER Lyman α survey at z = 2
Camargo: see rare designator prefixes
CAMB: see CMBFAST
Cambridge Automated Plate Measuring Machine: see plate measuring machine
Cambridge Automatic Plate Measuring Machine

APM Galaxy Survey: 1990s survey of galaxies in southern sky

Cambridge Catalog of Radio Sources: series of catalogs of northern hemisphere sources
Cambridge Discovery Park: location of SAO labs
Cambridge Interferometer

Third Cambridge Catalogue of Radio Sources: 1959 catalog of northern hemisphere 159-MHz sources

Cambridge OH Suppression Instrument: see United Kingdom Infrared Telescope
Cambridge Optical Aperture Synthesis Telescope (COAST): optical interferometer in England
- Mullard Radio Astronomy Observatory: radio observatory near Cambridge, UK
- optical interferometer: interferometer of visible light
camel: see AT2018cow
Camelopardalis: see rare designator prefixes
camera

GISMO: 2 mm bolometer camera on IRAM 30 m telescope
MUSTANG: bolometer array on the Green Bank Telescope
QUEST: sixteen square-degree survey camera
SCUBA: submillimeter instrument on James Clark Maxwell Telescope
TolTEC: sensitive infrared camera under construction for the LMT
WFC3: general purpose camera/spectroscope on HST

cameras

image stabilization: camera mechanism to compensate for movement

CAMISTIC: see Infrared Telescope Maffei
Campo Imperatore

Campo Imperatore Near-Earth Object Survey: survey of near-Earth objects

Campo Imperatore Near-Earth Object Survey: survey of near-Earth objects
CAMS: see Hitomi
Canada

Algonquin Radio Observatory: 46 meter radio telescope
Canadian Astronomical Society: professional astronomers
Canadian Hydrogen Intensity Mapping Experiment: radio telescope mapping distant neutral hydrogen
Canadian Institute for Theoretical Astrophysics: national research organization at University of Toronto
Centre for Research in Astrophysics of Quebec: astronomy collaboration of Quebec universities
CSA: includes astronomical research
Dominion Astrophysical Observatory: long-standing observatory in British Columbia
Dominion Observatory 10.03 MHz Source Catalog: 1960s survey of northern-hemisphere radio sources
Dominion Observatory 1420 MHz Source Catalog: 1960s survey of northern-hemisphere radio sources
Dominion Radio Astrophysical Observatory: radio observatory in British Columbia, Canada
Institute for research on exoplanets: U Montreéal division researching exoplanets
Institute of Space and Atmospheric Studies: U Saskatchewan research division
Large Zenith Telescope: 6 meter liquid mirror telescope in British Columbia
Queen's University Radio Observatory: early radio astronomy facility near Kingston, Ontario
Royal Astronomy Society of Canada: Canadian society supporting and promoting astronomy
Saskatoon: 1990s survey to measure CMB anisotropy
Sudbury Neutrino Observatory: Canadian underground neutrino detector

Canada-France Brown Dwarfs Survey (CFBDS): survey in search of brown dwarfs
Canada-France High-z Quasar Survey: 2000s distant quasar survey
Canada-France Redshift Survey: 1990s survey of galaxies to z = 1 to find associations of redshift to characteristics
Canada-France-Hawaii Telescope: 3.6-meter optical/infrared telescope in Hawaii
- Canada-France High-z Quasar Survey: 2000s distant quasar survey
- Canada-France Redshift Survey: 1990s survey of galaxies to z = 1 to find associations of redshift to characteristics
- Canadian Cluster Comparison Project: multi-wavelength survey of fifty X-ray-selected galaxy clusters
- CFBDS: survey in search of brown dwarfs
- CFHTLS: surveys of transients and stars
- Outer Solar System Origins Survey: 2013-2017 survey that searched for trans-Neptune objects
- SPIRou: CFHT spectropolarimeter for exoplanet research
Canada-France-Hawaii Telescope Legacy Survey (CFHTLS): surveys of transients and stars
Canadian

Canadian Astronomy Data Centre: online data distribution

Canadian Astronomical Society: professional astronomers
Canadian Astronomy Data Centre: online data distribution
Canadian Cluster Comparison Project: multi-wavelength survey of fifty X-ray-selected galaxy clusters
Canadian Hydrogen Intensity Mapping Experiment: radio telescope mapping distant neutral hydrogen
Canadian Hydrogen Observatory and Radio-transient Detector: see Canadian Hydrogen Intensity Mapping Experiment
Canadian Institute for Theoretical Astrophysics: national research organization at University of Toronto
Canadian Space Agency (CSA): includes astronomical research
CanariCam: see Gran Telescopio Canarias
Canary Islands

Cherenkov Telescope Array: ground gamma-ray telescope array in development
COSMOSOMAS: 1990s-2000s microwave survey
GOTO: telescope array to follow up gravitational wave signals
Gran Telescopio Canarias: 10.4 meter telescope in the Canary Islands
HARPS-N: high-precision spectrograph for exoplanet searches in Canary Islands
Isaac Newton Group of Telescopes: three telescopes in Canary Islands
Isaac Newton Telescope: 2.5 m telescope in Canary Islands
Large Earth-based Solar Telescope: 1990s plan for 2.4 m solar telescope
Liverpool Telescope: 2-meter robotic telescope in Spain
LSPE-STRIP: CMB survey telescope in Canary Islands
MAGIC: ground gamma-ray telescope array in the Canary Islands
MASCARA: distributed array of telescopes to search for exoplanets
Mercator Telescope: 1.2 m telescope in the Canary Islands
Overwhelmingly Large Telescope: 100 m telescope plan
QUIJOTE: survey to measure the polarization of the CMB
Roque de los Muchachos Observatory: observatory at La Palma in the Canary Islands
SPECULOOS: search for Earth-like exoplanets orbiting nearby dim stars
STELLA: two robotic telescopes in Canary Islands
SuperWASP: broad Earth-based search for transiting planets
Teide Observatory: observatory on Mount Teide in the Canary Islands
Telescopio Nazionale Galileo: 3.58 m telescope in Canary Islands
Tenerife Experiment: 1980s-1990s survey of CMB anisotropies
Thirty Meter Telescope: extremely large telescope planned for Hawaii
Very Small Array: radio interferometer in Canary Islands
William Herschel Telescope: 4.2-meter telescope in the Canary Islands

Canberra Deep Space Communication Complex: see NASA Deep Space Network
CANCAM: see CAESAR
CANDELS (Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey): early-universe survey by HST
candidate

HD1: very distant 2022 galaxy candidate

candidate companion: possible object apparently orbiting a known object
Canes Venatici Cloud

galaxy cloud: substructure of a supercluster

Canes Venatici I

Milky Way subgroup: the Milky Way and its satellites

Canes Venatici II

Milky Way subgroup: the Milky Way and its satellites

Canfranc Underground Laboratory

ANAIS-112: dark matter detection experiment in Spain

CANGAROO: Collaboration between Australia and Nippon for a Gamma Ray Observatory in the Outback
Canis Major Dwarf

Milky Way subgroup: the Milky Way and its satellites

Canis Major Dwarf Galaxy: small irregular galaxy in the Local Group
Canis Major Overdensity (Canis Major Dwarf Galaxy): small irregular galaxy in the Local Group
canonical pulsar: see millisecond pulsar
Canopus: second brightest star in the sky
capacitance: see dielectric
capacitor: see dielectric
Cape Canaveral Air Force Station: Air Force launch facilities adjacent to Kennedy Space Center
Cape Observatory: see Bonner Durchmusterung Catalog
Cape Photographic Durchmusterung: see Bonner Durchmusterung Catalog
Capella: brightest star in Auriga
Capella Aa: see Capella
Capella Ab: see Capella
Capella H: see Capella
Capella L: see Capella
CAPMAP: early 2000s array that surveyed CMB polarization
CAPS: see Cassini
capture theory

nebular hypothesis: model positing solar system planets result from a solar disk

captured rotation (tidal locking): locked rotation of an orbiting body
CARA (California Association for Research in Astronomy): nonprofit aimed at operating Keck observatory
CARA (Center for Astrophysical Research in Antarctica): NSF science and technology center
carbide planet (carbon planet): theoretical planet type with more carbon than oxygen
carbon: element, C, atomic number 6
- acetylene: compound of two carbon and two hydrogen atoms
- alpha CO: ratio of CO emissions to H₂
- C⁺: ionized carbon missing one electron
- carbon burning: fusion reaction starting with carbon
- carbon dioxide: compound of carbon atom and two oxygen atoms
- carbon monoxide: compound of carbon and oxygen, one atom each
- carbon planet: theoretical planet type with more carbon than oxygen
- carbon star: star with more carbon than oxygen in its atmosphere
- carbonate-silicate cycle: long-term cycle that sequesters Earth carbon
- ethylene: compound of two carbon and four hydrogen atoms
- hydrocarbon: any compound of just carbon and hydrogen
- hydrogen cyanide: compound of hydrogen, carbon, and nitrogen, one atom each
- ionized carbon fine structure line: carbon line that traces distant star formation
- methane: compound of one carbon and 4 hydrogen atoms
- methylidyne: compound of one carbon and one hydrogen atom
- neutrons from carbon-13: process by which neutrons are freed in the s process
- polycyclic aromatic hydrocarbon: hydrocarbons consisting of meshes of benzene rings
- silicate weathering feedback: feedback mechanism stabilizing carbon in Earth atmosphere
carbon burning: fusion reaction starting with carbon
- magnesium: element, Mg, atomic number 12
- neon: element, Ne, atomic number 10
- nucleosynthesis: creation of atomic nuclei
- sodium: metal, Na, atomic number 11
Carbon CII Line in Post-Reionization and Reionization Epoch (CONCERTO): spectrometer aimed at mapping the [CII] line
carbon cycle

carbon dioxide: compound of carbon atom and two oxygen atoms

carbon dating: see radioactive dating
carbon deflagration: see Type Ia supernova
carbon detonation: see Type Ia supernova
carbon dioxide: compound of carbon atom and two oxygen atoms
- acidity: measure of the activity of hydrogen ions in a solution
- carbonate system: system governing water and CO2 in the presence of each other
- carbonate-silicate cycle: long-term cycle that sequesters Earth carbon
- silicate weathering feedback: feedback mechanism stabilizing carbon in Earth atmosphere
- Venus: second inner-most planet in the solar system
carbon fusion (carbon burning): fusion reaction starting with carbon
carbon monosulfide: see tracer
carbon monoxide: compound of carbon and oxygen, one atom each
- CO ladder: series of CO rotational spectral lines
Carbon Monoxide Mapping Array: planned experiment to observe epoch of reionization
Carbon Monoxide Power Spectrum Survey (COPSS): survey of CO from star forming epoch
carbon planet: theoretical planet type with more carbon than oxygen
carbon star: star with more carbon than oxygen in its atmosphere
carbon to oxygen ratio

carbon: element, C, atomic number 6

carbon, nitrogen$#44; oxygen: see CNO cycle
carbon-13

neutrons from carbon-13: process by which neutrons are freed in the s process

carbon-14: see radioactive dating
carbon-burning shell: see carbon burning
carbon-enhanced metal-poor: see carbon star
carbon-oxygen white dwarf: see white dwarf
carbon-rich Wolf-Rayet: see Wolf-Rayet star
carbonaceous: see meteorite
carbonaceous chondrite: stony meteorites with carbon compounds showing no melting
- meteorite: rock found on Earth that is the remnant of a meteor
carbonate

acidity: measure of the activity of hydrogen ions in a solution
carbonate system: system governing water and CO2 in the presence of each other

carbonate system: system governing water and CO2 in the presence of each other
carbonate-silicate cycle: long-term cycle that sequesters Earth carbon
- weathering: changes in surface due to contact with atmosphere
carbonic acid

acidity: measure of the activity of hydrogen ions in a solution
carbonate system: system governing water and CO2 in the presence of each other

carbyne (methylidyne): compound of one carbon and one hydrogen atom
care-powered mass loss: see Fulton gap
Carina: see rare designator prefixes
Carina Dwarf Spheroidal

Milky Way subgroup: the Milky Way and its satellites

Carina Nebula: HII region with stars and nebulae of interest
Carina OB1 association

Carina Nebula: HII region with stars and nebulae of interest

Carina-Sagittarius Arm: see spiral arm
Carl Sagan Institute: group researching finding life on other planets and moons
Carl Sagan Memorial Station: see Mars Pathfinder
Carlsberg Meridian Catalogue: series of astrometric catalogs from 19th century on
Carlsberg Meridian Telescope

Carlsberg Meridian Catalogue: series of astrometric catalogs from 19th century on

CARMA (Combined Array for Research in Millimeter-wave Astronomy): former array of radio telescopes in eastern California
- Owens Valley Radio Observatory: group of radio telescopes in California near the VLBA
CARMA EDGE: survey CO-mapping galaxies
CARMA Extragalactic Database for Galaxy Evolution (CARMA EDGE): survey CO-mapping galaxies
CARMENES: see Calar Alto Observatory
Carnegie Institute for Science

Carnegie Supernova Project: survey of supernovae lightcurves

Carnegie Supernova Project: survey of supernovae lightcurves
Carrington event: solar storm September 1-3 1859
Cart du Ciel: see Astrographic Catalog
CAS (Centre for Astrophysics and Supercomputing): research center at Swinburne University, Australia
CAS (Chinese Academy of Sciences): Chinese national scientific organization
Cas: see rare designator prefixes
Cas A (Cassiopeia A): supernova remnant visible for 300 years
CAS Space: Chinese commericial space-launch corporation
- Satech-01: Chinese experimental spacecraft
CASA: software package for radio interferometry image generation
CASA: see CASA-MIA
CASA-MIA: 1990s cosmic-ray detector in Utah
CASCA (Canadian Astronomical Society): professional astronomers
Case: see rare designator prefixes
Case-Hamburg Survey: 1950s-1970s survey(s) of OB stars
CASPER: initiative to design radio-astronomy instruments
CASPIR: see ANU 2.3m Telescope
CASS (Center for Advanced Space Studies): unit of Universities Space Research Association
CASS (Center for Astrophysics and Space Sciences): UC San Diego academic institute
Cassegrain reflector: reflector telescope with convex secondary mirror
Cassegrain telescope (Cassegrain reflector): reflector telescope with convex secondary mirror
Cassini: explorer spacecraft sent to Saturn
- radio science: radar and other methods of using radio to probe planets and moons
- Saturn: second largest planet in the solar system
Cassini Equinox

Cassini: explorer spacecraft sent to Saturn

Cassini Solstice

Cassini: explorer spacecraft sent to Saturn

Cassini-Huygens (Cassini): explorer spacecraft sent to Saturn
Cassiopeia A: supernova remnant visible for 300 years
CaSSIS: see Trace Gas Orbiter
Castro: hydrodynamics simulation software
casually connection regions: see inflation
CAT (Cosmic Anisotropy Telescope): 1990s interferometer to measure CMB variations
- Mullard Radio Astronomy Observatory: radio observatory near Cambridge, UK
cataclysmic variable (cataclysmic variable star): star whose magnitude is much brighter on occasion
cataclysmic variable star: star whose magnitude is much brighter on occasion
- variable star: star that varies in magnitude
Catalina Real-time Transient Survey

Catalina Sky Survey: survey of near-Earth objects

Catalina Sky Survey: survey of near-Earth objects
catalog (astronomical catalog): list of observed astronomical bodies including characteristics
- 2MASS Photometric Redshift Catalog: galaxy redshifts from 2MASS
- 87GB Catalog of Radio Sources: 1980s Green Bank radio survey
- A-LIST: catalog of templates of H-band spectra for SPS
- Abell Catalog: galaxy cluster catalog assembled over 1950s-1980s
- Aitken Double Star Catalogue: 1932 catalog with both multiple-star systems and non-orbiting double stars
- All-Sky Compiled Catalogue: 2001 catalog compiled from modern sources
- Arakelian Catalog: 1970s list of small/bright galaxies
- Arecibo General Catalog: catalog of galaxies to support ALFALFA surveys
- Arecibo Occultation Survey: 1960s radio survey using occultations by the Moon
- Arp-Madore Catalog of Southern Peculiar Galaxies: 1970s-1980s catalog from the UK Schmidt Survey
- Asiago Supernova Catalog: catalog of known supernovae and their galaxies
- Astrographic Catalog: historical star catalog of the whole sky to magnitude 11
- Astronomische Gesellschaft Katalog: 19th/20th century astrometric catalog
- Atlas of Galactic Nebulae: 1980s catalog of Milky-Way nebulae
- Atlas of Peculiar Galaxies: 1960s catalog-book with photos
- ATNF Pulsar Catalogue: online catalog of pulsars
- Barnard Catalog: 1919 catalog of dark nebulae
- Basel Open Cluster Catalogue: list of open clusters
- BAT6: sample of long GRBs
- Becker, White, and Edwards Catalog: 1990s radio catalog from a Green Bank 300ft Telescope survey
- Berkeley Open Cluster Catalogue: list of open clusters
- Bibliographic Catalog of Variable Stars: listing of references to variable stars
- Bologna Catalog of Globular Clusters: catalog of globular clusters in M31
- Bonner Durchmusterung Catalog: well-known astrometric catalog from late 1800s
- Boss General Catalog: 1936 catalog of 30,000 stars
- Bright Star Catalog: early 20th century catalog of 9000 stars
- Burnham Double Star Catalogue: 1906 catalog with multiple star systems and non-orbiting double stars
- Caldwell Catalog: small catalog for amateur astronomers as an adjunct to the Messier Catalog
- Cambridge Catalog of Radio Sources: series of catalogs of northern hemisphere sources
- Carlsberg Meridian Catalogue: series of astrometric catalogs from 19th century on
- Catalog of Azzopardi & Vigneau: probable stars in the SMC
- Catalog of Circumpolar Stars: list of over 4000 stars in northern part of the sky
- Catalog of Components of Double and Multiple Stars: 1994 catalog of 74000 such double-star components
- Catalog of Galaxies and Clusters of Galaxies: list of galaxies/clusters assembled in 1960s
- Catalog of Infrared Observations: collection of infrared observation data from numerous sources
- Catalog of Southern Groups of Galaxies: list of southern groups assembled in 1980s
- Catalog of Stellar Identification: a compilation of the catalogs, BD, CD, and CPD
- Catalog of Stellar Identifications: 1970s catalog cross referencing existing star catalogs
- Catalogue of Cometary Orbits: comet catalog updated since 1970s
- Catalogue of Discoveries and Identifications of Minor Planets: 1982 catalog from Minor Planet Center
- Catalogue of Galactic Planetary Nebulae: 1967 catalog
- Catalogue of Interacting Galaxies: begun in the 1950s
- Catalogue of Southern Double Stars: 1955 catalog with multiple star systems and non-orbiting double stars
- Catalogues of Fundamental Stars: series of astrometric catalogs from 19th century on
- Cederblad Catalog: list of bright nebulae
- Collinder Catalog: 1930s catalog of 471 open clusters
- Cosmic Lens All-sky Survey: 1990s/2000s radio survey aimed at gravitational lensing
- CRATES: catalog of 8.4 GHz data on radio sources
- Czernik Catalog: list of open clusters
- David Dunlap Observatory Catalog: catalog of dwarf galaxies
- Dickel-Wendker-Bieritz Catalog: list of HII regions in the Cygnus X star-forming region
- Dolidze-Dzimselejsvili Catalogue: list of 11 open clusters
- Dunlop Double Star Catalogue: 1829 catalog of double stars viewed from Australia
- Duus-Newell catalog: list of southern galaxies/clusters assembled in 1970s
- Ephemerides of Minor Planets: annual catalog on minor planet positions
- ESO/Uppsala Survey of the ESO (B) Atlas: 1970s southern all-sky survey
- Fairall Galaxy List: 1977 list of galaxies with bright nuclei
- Fourth Cambridge Catalog of Radio Sources: 1960s catalog of northern hemisphere 178 MHz sources
- Frank Ross's Catalog: high-proper-motion and variable stars catalogued by Frank Ross
- Galactic O Star Catalog: 2000s catalog of O-type stars
- General Catalogue of Stellar Radial Velocities: 1950s century catalog of 15000 stars with their radial velocities
- General Catalogue of Trigonometric Parallaxes: 1950s catalog of stars with parallax measures
- General Catalogue of Variable Stars: 20th/21st century catalog of 58000 variable stars
- General Coordinates Network: service reporting transients
- Gliese Catalogue of Nearby Stars: 1950s catalog of stars within 20 parsecs
- Gliese-Jahreiss Catalog: 1991 catalog of stars within 25 parsecs
- Gravitational Wave Galaxy Catalogue: list of probable galaxies for GW detections
- Gravitational Wave Transient Catalog: catalog of gravitational wave detections
- Green Bank 6-cm Radio Source Catalog: catalog of from 1980s northern-hemisphere radio survey
- Guide Star Catalog: catalog of stars to help aim HST
- Henry Draper Catalog: early 20th century spectroscopic catalog of stars
- Herschel Double Star Catalog: series of early double star catalogs
- Herz catalog: list of 3000 stars in a strip of the southern sky
- Hewitt & Burbidge Catalog: optical catalog of quasi-stellar objects
- Hickson Compact Groups: list of 100 galaxy groups
- Index Catalog: 1895 catalog of galaxies, star clusters, and other nebulae
- International Variable Star Index: variable star catalog by AAVSO
- ITEP-SAI Supernova Light Curve Catalogue: online catalog
- JWST Extragalactic Mock Catalog: mock catalog of distant infrared galaxies
- King Catalog: list of 21 open clusters
- Konus-Wind catalog: catalog of GRBs from the Wind spacecraft
- Lépine Shara Proper Motion catalog: 2000s catalog of stars with proper motion
- Lacaille Star Catalog: 1700s catalog of about 10,000 southern hemisphere stars
- LEDA: galaxy database with observation data
- Lowell Proper Motion Survey: 1950s-1970s catalogs of stars with proper motion
- Lund Catalogue of Open Clusters: list of open clusters
- Luyten Double Star Survey: 1940s-1970s catalog of double stars
- 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
- Lynds Catalog of Dark Nebulae: 1950s/1960s list of dark nebulae found on Palomar plates
- Lynds Catalogue of Bright Nebulae: 1950s/1960s list of bright nebulae found on Palomar plates
- MaNGA Stellar Library: catalog of SEDs of representative stars
- MASH Catalog of Planetary Nebulae: 995 possible planetary nebulae
- Max Wolf's catalog of stars with proper motion: early 20th century catalog of 1500 stars
- Melotte Catalog: 1915 catalog of open and globular clusters
- Messier Catalog: catalog of astronomical objects to avoid when looking for comets
- MIT X-ray Burst Source Catalog: 1970s catalog of X-ray bursters
- Molonglo Reference Catalog: 1981 catalog of mostly southern hemisphere radio sources
- Morphological Catalogue of Galaxies: 1960s catalog from Palomar plates
- MSH Catalog: 1950s catalog of radio sources from a Mills Cross survey
- N30 Catalog: 1950s catalog collecting proper motion data from older catalogs
- New Catalogue of Suspected Variable Stars: catalog from latter half of 20th century catalog
- New General Catalogue: 1888 catalog of galaxies, star clusters, and other nebulae
- NOAO Source Catalog: catalog compiled from NOAO public data
- NOMAD: astrometric star catalog
- Ogle Galaxy Catalog: catalog of luminous galaxies
- Ohio Radio Survey: 1960s radio survey by Ohio State University
- Open Exoplanet Catalogue: independently maintained list of known exoplanets
- Palomar Globular Clusters: list of 15 globular clusters found in POSS plates
- Palomar-Haro-Luyten Catalog: 1960s catalog of faint blue stars
- Pantheon: catalog of well-checked Type Ia supernovae
- Parkes Catalog: catalog of from 1960s-1990 of radio sources in southern hemisphere
- Parsamian Nebula Catalog: 1965 list of nebulae
- Polar-ring Catalog: 1990 catalog of polar-ring galaxies
- PPM Star Catalogue: 1991 astrometric catalog with proper motions
- Principal Galaxies Catalog: modern catalog of more than 70k galaxies
- Radcliffe Observatory Magellanic Clouds Catalogue: catalog of stars in
- RASS/Green Bank Catalog: combined list of radio galaxies from Rosat and Green Bank surveys
- Reference Catalogue of Bright Galaxies: series of catalogs of nearby galaxies
- Roma-BZCAT: 2008 catalog of blazars
- SAO Star Catalog: 1960s catalog
- SDSS-DR12 Quasars: catalog of quasar information in SDSS DR12
- SDSS-DR16 Quasars: catalog of quasar information in SDSS DR16
- Shapley-Ames Catalog: 1932 catalog of contemporary data on 1249 galaxies
- Sharpless Catalog: catalog of HII regions found on Palomar plates
- Spectroscopic Properties of Cool Stars: analysis of spectroscopic data of 7000+ M and L stars
- Strasbourg-ESO Catalog of Galactic Planetary Nebulae: 1992 catalog of 1820 objects
- Struve Catalogs: two catalogs of double stars
- Texas Survey of Radio Sources at 365 MHz: 1970s/1980s radio survey made with the Texas Interferometer
- Third Cambridge Catalogue of Radio Sources: 1959 catalog of northern hemisphere 159-MHz sources
- Transient Name Server: online catalog of transients
- Uppsala General Catalogue: 1973 catalog of galaxies visible from northern hemisphere
- USNO CCD Astrograph Catalog: USNO star catalog including proper motions
- USS Sources: catalog of sources with steep spectral index
- UZC-SSRS2 Group Catalog: 2002 catalog of galaxy groups
- Van Den Bergh Reflection Nebula Catalog: catalog of reflection nebulae found in POSS plates
- Villanova White Dwarf Catalog: ongoing catalog of white dwarfs
- Virgo Cluster Catalog: 1980s catalog of 2000 galaxies
- Washington Double Star Catalog: modern database of double stars
- WISE x SuperCOSMOS photometric redshift catalog: catalog of distant galaxies in WISE and SuperCOSMOS
- WISeREP: interactive catalog of supernovae
- XZ Catalog of Zodiacal Stars: 1977 catalog of stars near the ecliptic
- Yale Observatory Zone Catalog: mid-20th century catalogs totaling 400,000 stars
Catalog of 5,268 Standard Stars, 1950.0 Based on the Normal System N30 (N30 Catalog): 1950s catalog collecting proper motion data from older catalogs
Catalog of Azzopardi & Vigneau: probable stars in the SMC
Catalog of Circumpolar Stars: list of over 4000 stars in northern part of the sky
Catalog of Components of Double and Multiple Stars: 1994 catalog of 74000 such double-star components
Catalog of Dark Nebulae (Lynds Catalog of Dark Nebulae): 1950s/1960s list of dark nebulae found on Palomar plates
Catalog of Galaxies and Clusters of Galaxies: list of galaxies/clusters assembled in 1960s
Catalog of Infrared Observations: collection of infrared observation data from numerous sources
Catalog of Nearby Stars (Gliese Catalogue of Nearby Stars): 1950s catalog of stars within 20 parsecs
Catalog of Southern Groups of Galaxies: list of southern groups assembled in 1980s
Catalog of Stellar Identification: a compilation of the catalogs, BD, CD, and CPD
Catalog of Stellar Identifications: 1970s catalog cross referencing existing star catalogs
catalog-based designator (survey-based designator): astronomical object designators based on name of survey
catalogs

Astrocats: software to create and manage an astronomy catalog
astronomical catalog: list of observed astronomical bodies including characteristics

catalogue (astronomical catalog): list of observed astronomical bodies including characteristics
Catalogue des Nebuleuses et des Amas d'Etoiles (Messier Catalog): catalog of astronomical objects to avoid when looking for comets
Catalogue of Bright Nebulae (Lynds Catalogue of Bright Nebulae): 1950s/1960s list of bright nebulae found on Palomar plates
Catalogue of Cometary Nebulae Discovered on Palomar Maps (Parsamian Nebula Catalog): 1965 list of nebulae
Catalogue of Cometary Orbits: comet catalog updated since 1970s
Catalogue of Discoveries and Identifications of Minor Planets: 1982 catalog from Minor Planet Center
Catalogue of Galactic Planetary Nebulae: 1967 catalog
Catalogue of Interacting Galaxies: begun in the 1950s
Catalogue of Nearby Stars

Gliese-Jahreiss Catalog: 1991 catalog of stars within 25 parsecs

Catalogue of Nebulae and Clusters of Stars: see New General Catalogue
Catalogue of Nebulae and Star Clusters (Messier Catalog): catalog of astronomical objects to avoid when looking for comets
- nebula: cloud of dust and gas
Catalogue of Rich Clusters of Galaxies (Abell Catalog): galaxy cluster catalog assembled over 1950s-1980s
Catalogue of Selected Compact Galaxies and of Post-eruptive Galaxies: see Catalog of Galaxies and Clusters of Galaxies
Catalogue of Southern Double Stars: 1955 catalog with multiple star systems and non-orbiting double stars
Catalogues of Fundamental Stars: series of astrometric catalogs from 19th century on
Catalogus Britannicus

Flamsteed designation: star designation system dating from 1700s

cation: see ion
CATS345: see Atacama Submillimeter Telescope Experiment
Cauchy distribution (Lorentzian distribution): probability distribution applicable to some physics phenomena
caustic structure: see core-cusp problem
cavity-enhanced absorption spectroscopy: passing a beam through a gas multiple times to amplify absorption lines
CB: see rare designator prefixes
CBAT (Central Bureau for Astronomical Telegrams): organization reporting transients and discoveries
CBB: see rare designator prefixes
CBET: see Central Bureau for Astronomical Telegrams
CBF: see rare designator prefixes
CBI (Cosmic Background Imager): radio telescope in Chile observing the CMB
- Llano de Chajnantor Observatory: group of observatories on a high plateau of the Atacama Desert
CBI2: see Cosmic Background Imager
CBR (cosmic background radiation): electromagnetic radiation coming from every direction
CBR (cosmic microwave background): microwave radiation coming from every direction
- cosmic gamma ray background: gamma-ray radiation seen everywhere
- cosmic infrared background: widespread infrared radiation not associated with known sources
- cosmic optical background: widespread optical radiation not associated with known sources
- cosmic X-ray background: X-ray radiation coming from outside the Milky Way
- diffuse emission: electromagnetic radiation not confined to a point source
- extragalactic background light: electromagnetic radiation from star formation and AGNs
CBS: see rare designator prefixes
CC (candidate companion): possible object apparently orbiting a known object
CC (carbonaceous chondrite): stony meteorites with carbon compounds showing no melting
CC meteorite (carbonaceous chondrite): stony meteorites with carbon compounds showing no melting
CCAFS (Cape Canaveral Air Force Station): Air Force launch facilities adjacent to Kennedy Space Center
CCAT: 25-meter submillimeter telescope plan for Chile
- Atacama Desert: Chilean high-altitude, dry plateau with numerous observatories
- Llano de Chajnantor Observatory: group of observatories on a high plateau of the Atacama Desert
CCAT-p (Fred Young Submillimeter Telescope): 6-meter submillimeter survey telescope under construction in Chile
- Atacama Desert: Chilean high-altitude, dry plateau with numerous observatories
CCAT-prime (Fred Young Submillimeter Telescope): 6-meter submillimeter survey telescope under construction in Chile
CCCP (Canadian Cluster Comparison Project): multi-wavelength survey of fifty X-ray-selected galaxy clusters
CCCP: see rare designator prefixes
CCCS: see rare designator prefixes
CCD: type of electronic device to detect light
CCD (color-color diagram): means of comparing characteristics of stars
- ACIS: imaging spectrometer on Chandra X-ray telescope
- parts per million: method of expressing a small ratio
- photometry: studying starlight using optical filters
- quantum efficiency: measure of instrument's ability to sense EMR
CCD photometry: see photometry
CCDM (Catalog of Components of Double and Multiple Stars): 1994 catalog of 74000 such double-star components
CCDs

DAOPHOT: 1980s CCD photometry software
integration time: time spent acquiring a signal

CCL: see European Southern Observatory Very Large Telescope
CCM: see rare designator prefixes
CCO (Catalogue of Cometary Orbits): comet catalog updated since 1970s
CCO: see compact object
CCOR: see SWFO-L1
CCS: see carbon star
CCS: see rare designator prefixes
CCSN (core collapse supernova): supernova resulting from the collapse of the core of a star
- supernova progenitor: the star or star system that produces a supernova
CCSN progenitor: see supernova progenitor
CD: see Bonner Durchmusterung Catalog
cD: see giant elliptical galaxy
cD galaxy: see giant elliptical galaxy
- elliptical galaxy: ellipsoidal-shaped galaxy
CDA: see Cassini
CDF-N (Chandra Deep Field North): X-ray deep survey encompassing HDF region
CDF-North (Chandra Deep Field North): X-ray deep survey encompassing HDF region
CDF-S (Chandra Deep Field South): X-ray deep survey encompassing HDF-South region
- Spitzer Extragalactic Representative Volume Survey: infrared survey of some well-studied fields
CDF-South (Chandra Deep Field South): X-ray deep survey encompassing HDF-South region
CDFN (Chandra Deep Field North): X-ray deep survey encompassing HDF region
CDFS (Chandra Deep Field South): X-ray deep survey encompassing HDF-South region
- FourStar Galaxy Evolution Survey: infrared deep-survey to detect galaxies
CDIM (Cosmic Dawn Intensity Mapper): NASA concept for space telescope for intensity mapping
CDIMP (Catalogue of Discoveries and Identifications of Minor Planets): 1982 catalog from Minor Planet Center
CDISORT

DISORT: simulation of radiative transfer in an atmosphere

CDM (cold dark matter): one of three classes of "particle dark matter" theory
CDM: see Bonner Durchmusterung Catalog
CDM: see dark matter
- fuzzy dark matter: concept of extremely light dark matter particles
- sub-GeV dark matter: a more-massive type of CDM
CDMS (Cryogenic Dark Matter Search): a search for a candidate dark matter particle
CDMS I: see Cryogenic Dark Matter Search
CDMS II: see Cryogenic Dark Matter Search
CDMSlite: see Cryogenic Dark Matter Search
CDP (Cambridge Discovery Park): location of SAO labs
CDPP (combined differential photometric precision): calculated relation of photometric variation to SNR
CDS (Centre de données astronomiques de Strasbourg): repository of astronomical data
CDS: see Solar and Heliospheric Observatory
- SIMBAD: online database of astronomical objects
CDSCC: see NASA Deep Space Network
CE (Cosmic Explorer): concept for a very large LIGO-like GW detector
CE (chemical equilibrium): state where chemical makeup is unchanging
CE (common envelope): binary star system surrounded by a single gas cloud
CE: see post-common-envelope binary
CE: see rare designator prefixes
CE1: see Cosmic Explorer
CE2: see Cosmic Explorer
CEA

CEA Service d'Astrophysique: French national astrophysics research institute

CEA SAp (CEA Service d'Astrophysique): French national astrophysics research institute
CEA Service d'Astrophysique: French national astrophysics research institute
CEAS (cavity-enhanced absorption spectroscopy): passing a beam through a gas multiple times to amplify absorption lines
CEB: see common envelope
CEB: see post-common-envelope binary
CEBE: see common envelope
CEBE: see post-common-envelope binary
Ced (Cederblad Catalog): list of bright nebulae
CEDAG: see rare designator prefixes
Cederblad: see Cederblad Catalog
Cederblad Catalog: list of bright nebulae
CEDUNA

Long Baseline Array: radio interferometer using Australian telescopes

CEERS: JWST early release observation program covering the EGS
CEERS: see James Webb Space Telescope
CEL: see rare designator prefixes
Celescope: see Orbiting Astronomical Observatory
celestial: having to do with stars and the sky
celestial body (astronomical object): planet, star, galaxy, etc.
celestial coordinate system: system for specifying position of celestial objects
celestial coordinates: see celestial coordinate system
celestial equator: equator-like line around the celestial sphere
- celestial coordinate system: system for specifying position of celestial objects
celestial event: something astronomical occurring visibly in the sky
celestial mechanics: study of forces and motion of celestial objects
- anomalistic year: planet's time between successive periapses
- apsis: closest or furthest point in an eccentric orbit
- disk: rotating disk-shaped object such as disk galaxy or circumstellar disk
- eccentricity: degree to which an orbit is non-circular
- Hill stability: planetary orbits which will remain in the same order
- Kozai mechanism: an effect on an orbit by another, more distant orbiting body
- Lagrange stability: a quality of some stable orbits
- Lie transform: type of infinitesimal transform
- Lindblad resonance: resonant orbits within a disk due to a high-density portion
- Lynden-Bell mechanism: a model for galaxy bar formation
- mechanics: the science of forces and motions
- orbital decay: gradual reduction in radius of an orbit
- orbital element: parameters describing an orbit
- orbital period: length of time for an orbiting object to complete one cycle
- orbital resonance: tendency of orbits of multiple bodies to remain in a simple pattern
- orbital speed: speed of an orbiting body around the barycenter of a system
- period derivative: rate of change in the period of an orbit or rotation
- projected semi-major axis: semi-major axis projected onto line-of-sight or plane of the sky
- Q factor: measure of oscillator's damping
- semi-major axis: maximum radius of an ellipse
- synchronous orbit: orbit with angular velocity matching the rotation of the orbited body
celestial meridian: celestial sphere's meridian passing overhead
- meridian: circle around the Earth passing through both poles
- transit: a celestial body passing between another and an observer
celestial navigation: navigating such as across the sea, using the stars
- asterism: easily recognizable star pattern
celestial north pole: see celestial pole
- celestial equator: equator-like line around the celestial sphere
- position angle: indication of a direction across the celestial sphere
celestial object (astronomical object): planet, star, galaxy, etc.
celestial pole: point within the celestial sphere aligned with Earth's rotation axis
- celestial equator: equator-like line around the celestial sphere
- celestial meridian: celestial sphere's meridian passing overhead
celestial reference frame: frame of reference associated with a catalog of stars or quasars
- Gaia Celestial Reference Frame: celestial reference frame based upon Gaia data
- Hipparcos Celestial Reference Frame: astronomical reference frame based upon Hipparcos catalog
- ICRF: celestial reference frame based upon quasars
celestial south pole: see celestial pole
- celestial equator: equator-like line around the celestial sphere
celestial sphere: the sky in considered as a sphere surrounding the observer
- appulse: moment of apparent nearest distance of observed bodies
- celestial coordinate system: system for specifying position of celestial objects
- celestial equator: equator-like line around the celestial sphere
- celestial meridian: celestial sphere's meridian passing overhead
- celestial pole: point within the celestial sphere aligned with Earth's rotation axis
- declination: direction coordinate above/below celestial equator
- ecliptic: path of the Sun on the celestial sphere as seen from Earth
- ecliptic coordinate system: celestial coordinate system system based upon Earth's orbital plane
- epoch: when an object was at a particular set of celestial coordinates
- equatorial coordinate system: latitude/longitude-like system for the celestial sphere
- equinox: point-in-time when tilt of Earth is neither toward nor away from the Sun
- galactic anticenter: direction opposite the galactic center
- galactic coordinate system: celestial coordinate system system based upon the galactic plane
- galactic north: determination of the more northern direction of the Milky Way's axis
- horizontal coordinate system: celestial coordinate system based upon horizon and north
- International Celestial Reference System: standardized variation of equatorial coordinate system
- position angle: indication of a direction across the celestial sphere
- Radio Optical Reference Frame: 1994 celestial reference frame based on 436 sources
- right ascension: direction coordinate along celestial equator
- solar apex: direction that the Sun is moving compared to nearby stars
- substellar point: point on a body such that a particular star is at the zenith
- supergalactic coordinate system: celestial coordinate system system based upon the supergalactic plane
- zenith: spot on the sky directly above something
CELIAS: see Solar and Heliospheric Observatory
cell

Hadley cell: circulation pattern of up at the equator, poleward, down, and back
zonal flow: east-west air circulation
zone: apparent "horizontal" band in an atmosphere

Celsius

kelvin: unit of temperature scale starting at absolute zero

CELT (California Extremely Large Telescope): concept for an extremely large telescope
CEMP: see carbon star
CEMP-no: see carbon star
CEMP-r: see carbon star
CEMP-r/s: see carbon star
CEMP-s: see carbon star
centaur: asteroid-like body orbiting among the outer planets
- 10199 Chariklo: largest minor planet in the outer solar system
Centaur rocket stage

LCROSS: space probe observing the lunar poles

centaurs

minor planet: lesser solar system body without comet characteristics
solar system object: the Sun, solar system planets, minor planets, comets, and moons

Centaurus

Sloan Great Wall: large slab of galaxies discovered in SDSS

Centaurus A: nearby radio galaxy
- Council of Giants: twelve large galaxies surrounding the Local Group
Centaurus A Subgroup: see Centaurus A
Centaurus A/M83 Group: see Centaurus A
Center for Advanced Space Studies: unit of Universities Space Research Association
Center for Astronomy of Heidelberg University

Institute of Theoretical Astrophysics: Heidelberg research institute

Center for Astrophysical Research in Antarctica: NSF science and technology center
Center for Astrophysics: Harvard and Smithsonian research and education organization
- CfA Redshift Survey: 1970s-1990s surveys of galaxy redshifts
Center for Astrophysics and Space Sciences: UC San Diego academic institute
Center for Astrophysics Redshift Survey (CfA Redshift Survey): 1970s-1990s surveys of galaxy redshifts
Center for Earth and Planetary Studies: Smithsonian Institute research unit
Center for High Angular Resolution Astronomy (CHARA): optical interferometer on Mount Wilson
- Mount Wilson Observatory: Los Angeles observatory with Hooker telescope
- optical interferometer: interferometer of visible light
center of gravity: see barycenter
center of mass (barycenter): center of mass of two orbiting bodies
- reduced mass: the reciprocal of the sum of the reciprocals of the masses of two objects
center of the Milky Way (galactic center): region at the middle of the Milky Way
center-of-mass frame of reference: see barycenter
centigrade

kelvin: unit of temperature scale starting at absolute zero

centimeter size barrier: see barrier
centimeter-gram-second system (CGS): metric system variant
centimeter-wave astronomy: see radio astronomy
central body (primary): central body of a system such as the Sun within the solar system
Central Bureau Electronic Telegram: see Central Bureau for Astronomical Telegrams
Central Bureau for Astronomical Telegrams: organization reporting transients and discoveries
central compact object: see compact object
central galaxy: see giant elliptical galaxy
central limit theorem

Gaussian function: function producing the bell curve
normal distribution: familiar probability distribution with bell curve shape

central peak: see complex crater
central star of the planetary nebula: see planetary nebula
central-peak crater: see complex crater
Centre de données astronomiques de Strasbourg: repository of astronomical data
- SIMBAD: online database of astronomical objects
Centre for Astrophysics and Supercomputing: research center at Swinburne University, Australia
Centre for Research in Astrophysics of Quebec: astronomy collaboration of Quebec universities
Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference: IAU initiative to address the issue of satellite constellations
Centre national d'ètudes spatiales: French space agency
Centre national de la recherche scientifique: French scientific research organization
Centre Pédagogique Planète Univers: see GI2T
centripetal force: whatever force keeps an object moving in circles
Centro Astronómico Hispano-Alemán: German-Spanish Astronomical Center at Calar Alto.
CEP (Cepheid variable): type of star that varies with a constant period
Cepheid (Cepheid variable): type of star that varies with a constant period
Cepheid P-L relation: see Cepheid variable
Cepheid variable: type of star that varies with a constant period
- pulsating star: variable star that varies through energy pulses
CEPS (Center for Earth and Planetary Studies): Smithsonian Institute research unit
Ceres: dwarf planet and largest asteroid
- Dawn: explorer spacecraft sent to asteroids Vesta and Ceres
- dwarf planet: round like a planet, only smaller
- facula: bright spot on a planet or the Sun
- planet: round object orbiting a star that clears out its own orbital path
- protoplanet: simplest, least-developed object classified as a planet
- solar system object: the Sun, solar system planets, minor planets, comets, and moons
- Titius-Bode law: relationship between the distances between solar system planets
CERGA observatory: see GI2T
CERN

particle physics: physics such as carried out in accelerators

Cerro Armazones Observatory

European Extremely Large Telescope: 39-meter telescope under construction

Cerro Chajnantor: see Llano de Chajnantor Observatory
- Fred Young Submillimeter Telescope: 6-meter submillimeter survey telescope under construction in Chile
Cerro Chajnantor Atacama Telescope (CCAT): 25-meter submillimeter telescope plan for Chile
Cerro Chajnantor Atacama Telescope, prime (Fred Young Submillimeter Telescope): 6-meter submillimeter survey telescope under construction in Chile
Cerro Pachón

Gemini Observatory: pair of telescopes in Hawaii and Chile

Cerro Paranal: see Paranal Observatory
Cerro Toco: see Llano de Chajnantor Observatory
Cerro Tololo

All Sky Automated Survey for SuperNovae: survey of both hemispheres for supernovae

Cerro Tololo Inter-American Observatory: NOIRLab observatory in Chile with Blanco telescope
- Calán/Tololo Supernova Survey: late 1980s to early 1990s search to redshift 0.1
- CTIO Upper-Scorpius OB Association Survey: survey of low-mass stars and brown dwarfs
- Dark Energy Survey: survey aimed at mapping the universe's expansion
- DECaLS: survey imaging part of SDSS footprint with DECam
- Deep Lens Survey: investigating mass distribution of the universe
- Evryscope: automated array of telescopes to uncover transients
- Kitt Peak National Observatory: NOIRLab observatory in Arizona with Mayall telescope
- Multiwavelength Survey by Yale-Chile: optical/NIR survey of four deep fields
- National Optical Astronomy Observatory: previous name of US optical astronomy organization
- NOAO Deep Wide-field Survey: survey investigating large scale structure of the universe
- SOAR Telescope: 4.1 m reflector telescope in Chile
- USNO Twin Astrograph: USNO astrograph deployed in 1970
- Víctor M. Blanco Telescope: 4 meter reflector telescope in Chile
CERTO: see ARGOS
CES: see ESO 3.6m Telescope
CES: see New Technology Telescope
CfA (Center for Astrophysics): Harvard and Smithsonian research and education organization
CfA: see CfA Redshift Survey
- Astrophysics Data System: online astrophysics bibliography and paper archive
CfA digital speedometer: 1980s/90s spectrograph aimed at radial velocity measurements
CfA Redshift Survey: 1970s-1990s surveys of galaxy redshifts
- Great Wall: large slab of galaxies
CfA1 Survey: see CfA Redshift Survey
CfA2 Great Wall (Great Wall): large slab of galaxies
CfA2 Survey: see CfA Redshift Survey
CFBD: see CFBDS
CFBDS: survey in search of brown dwarfs
CFBDSIR: see CFBDS
CFD

lattice Boltzmann method: computational fluid dynamics method treating the fluid as particles

CFH telescope (Canada-France-Hawaii Telescope): 3.6-meter optical/infrared telescope in Hawaii
CFH12k: see Canada-France-Hawaii Telescope
- Canadian Cluster Comparison Project: multi-wavelength survey of fifty X-ray-selected galaxy clusters
CFHQS (Canada-France High-z Quasar Survey): 2000s distant quasar survey
CFHT (Canada-France-Hawaii Telescope): 3.6-meter optical/infrared telescope in Hawaii
- Canada-France High-z Quasar Survey: 2000s distant quasar survey
- Canada-France Redshift Survey: 1990s survey of galaxies to z = 1 to find associations of redshift to characteristics
- Canadian Cluster Comparison Project: multi-wavelength survey of fifty X-ray-selected galaxy clusters
- CFBDS: survey in search of brown dwarfs
- CFHTLS: surveys of transients and stars
- Dynamical Analysis of Nearby Clusters: survey of stars in stellar clusters
- Mauna Kea: Hawaiian mountain, the site of observatories
- Mauna Kea Observatories: observatories on Mauna Kea in Hawaii
- Multi-Epoch Nearby Cluster Survey: Type Ia supernova survey in clusters at z = 0.1
- Outer Solar System Origins Survey: 2013-2017 survey that searched for trans-Neptune objects
- PAndAS: survey of M31 and M33
- SPIRou: CFHT spectropolarimeter for exoplanet research
- Supernova Legacy Survey: detect and monitor supernovae to measure the effects of dark energy
CFHT-BD-Tau: see CFBDS
CFHTLS: surveys of transients and stars
- AEGIS: early 2000s survey study of distant galaxies
CFHTLS-D1: see CFHTLS
CFHTWIR-Oph: see rare designator prefixes
CFL condition: see finite difference method
CFRS (Canada-France Redshift Survey): 1990s survey of galaxies to z = 1 to find associations of redshift to characteristics
CFS: see Astrographic Catalog
CFT (conformal field theory): a type of quantum field theory
CG: see Bok globule
CG: see Cos-B
CG: see barycenter
CG: see dwarf galaxy
CG: see rare designator prefixes
CGB (cosmic gamma ray background): gamma-ray radiation seen everywhere
- cosmic background radiation: electromagnetic radiation coming from every direction
CGCG (Catalog of Galaxies and Clusters of Galaxies): list of galaxies/clusters assembled in 1960s
CGCG 137-068

AT2018cow: unusual 2018 optical transient

CGCS: see carbon star
CGCS: see rare designator prefixes
CGI: see Roman Space Telescope
CGM (circumgalactic medium): gas surrounding a galaxy
CGMW: see rare designator prefixes
CGO: see rare designator prefixes
CGPG: see Catalog of Galaxies and Clusters of Galaxies
CGRO (Compton Gamma Ray Observatory): 1990s space observatory for gamma ray observation
- General Coordinates Network: service reporting transients
CGS: metric system variant
- erg: CGS unit of energy
- gauss: measurement of magnetic field β
- magnetic flux: measure of magnetism passing through a surface
- magnetic flux density: vector field describing magnetism in relation to the Lorentz force
- SI: standardized metric system
CGS4: see United Kingdom Infrared Telescope
CGSS: see rare designator prefixes
CH (Canadian Hydrogen Intensity Mapping Experiment): radio telescope mapping distant neutral hydrogen
CH (methylidyne): compound of one carbon and one hydrogen atom
CH star: see chemically peculiar star
- methylidyne: compound of one carbon and one hydrogen atom
CH₃D: see methane
CH₄ (methane): compound of one carbon and 4 hydrogen atoms
Cha: see rare designator prefixes
Cha Halpha: see rare designator prefixes
Chabrier IMF: see initial mass function
CHAI: see CCAT
CHAI: see Fred Young Submillimeter Telescope
Chajnantor Observatory (Llano de Chajnantor Observatory): group of observatories on a high plateau of the Atacama Desert
- Atacama Desert: Chilean high-altitude, dry plateau with numerous observatories
Chajnantor Plateau: see Llano de Chajnantor Observatory
Challenger

SPARTAN: series of astronomy satellites launched/retrieved by Space Shuttles

Chandler wobble: shifting of the Earth's axis of rotation relative to the Earth itself
- nutation: precession of a body's axis of rotation
- photographic zenith tube: telescope permanently mounted to the zenith
Chandra (Chandra X-ray Observatory): space X-ray telescope
- ACIS: imaging spectrometer on Chandra 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
- COUP: survey of X-ray sources in the Orion Nebula
- Extended Chandra Deep Field-South Survey: 1100 square arcminute X-ray survey
- GOALS: across-spectrum observation of 200 LIRGs
- GOODS: survey combining data from different sources on very distant objects
Chandra Carina Complex Project: see Canadian Cluster Comparison Project
Chandra COSMOS Survey: see Cosmic Evolution Survey
Chandra Deep Field North: X-ray deep survey encompassing HDF region
Chandra Deep Field South: X-ray deep survey encompassing HDF-South region
- Spitzer Extragalactic Representative Volume Survey: infrared survey of some well-studied fields
Chandra Deep Fields

Chandra Deep Field North: X-ray deep survey encompassing HDF region

Chandra Interactive Analysis of Observations: software for analyzing Chandra X-ray data
Chandra Orion Ultradeep Project (COUP): survey of X-ray sources in the Orion Nebula
Chandra X-ray Observatory: space X-ray telescope
- ACIS: imaging spectrometer on Chandra X-ray telescope
Chandrasekhar friction (dynamical friction): drag produced by gravitational interaction with surrounding objects
Chandrasekhar limit: maximum mass of a white dwarf
Chandrasekhar mass (Chandrasekhar limit): maximum mass of a white dwarf
Chang'e 3

Lunar-based Ultraviolet Telescope: Chinese ultraviolet telescope on the Moon

ChaNGa: cosmological-simulation project active since circa 2015
- N-body simulation: simulation of many objects gravitationally-bound to each other
- Romulus simulations: cosmological-simulation project active since circa 2015
changing-look AGN: see active galactic nucleus
chaos

Lyapunov time: timescale beyond which a dynamical system is chaotic

chaos theory: theory of systems highly sensitive to initial conditions
CHARA: optical interferometer on Mount Wilson
- Mount Wilson Observatory: Los Angeles observatory with Hooker telescope
- optical interferometer: interferometer of visible light
CHARA array (CHARA): optical interferometer on Mount Wilson
CHARA/SPICA: see CHARA
characteristic age (pulsar characteristic age): approximate age determination of a pulsar based upon rotation rate
characteristic magnetic field: see pulsar characteristic age
characteristic strain: see gravitational wave strain
Characterizing Exoplanet Satellite (CHEOPS): space telescope in development to measure radii of exoplanets
charge

quantum number: number representing a conserved quantity

charge barrier (electrostatic barrier): the problem that dust grains will repel and not join to form planet seeds
- barrier: challenging issue regarding planet formation
charge exchange: see atmospheric escape
charge-coupled device (CCD): type of electronic device to detect light
- quantum efficiency: measure of instrument's ability to sense EMR
charged black hole: see black hole model
charged current interaction: see weak interaction
charged particle

spark chamber: type of ion detector

Chariklo (10199 Chariklo): largest minor planet in the outer solar system
- centaur: asteroid-like body orbiting among the outer planets
CHARIS: see Subaru Telescope
charm: see flavor
Charm N-body Gravity (ChaNGa): cosmological-simulation project active since circa 2015
charm quark: see particle
charm quark: see quark
- standard model: model of elementary particles including quarks
Charm++

ChaNGa: cosmological-simulation project active since circa 2015

Charon: see Pluto
- Earth: third solar system planet from the Sun
- moon: a planet's natural satellite, such as Earth's
- synchronous orbit: orbit with angular velocity matching the rotation of the orbited body
CHE: see double star designation
ChemCam: see Mars Science Laboratory
chemical abundance ratio: see bracket notation
- metallicity: metal fraction of an object
chemical abundances (abundances): relative amounts of each chemical element
chemical composition (abundances): relative amounts of each chemical element
chemical composition of the universe: see abundances
chemical differentiation

atmosphere: gas surrounding astronomical object

chemical element (element): class of atom based on its number of protons
chemical equilibrium: state where chemical makeup is unchanging
- carbonate system: system governing water and CO2 in the presence of each other
- thermal equilibrium: state of a system with no net heat flows
chemical evolution: see abundances
chemical kinetics: see chemical equilibrium
chemical species: see reduction potential
chemical tagging: using abundances to trace the origin of particular stars
chemically peculiar star: star with SED showing presence metals unusual for stars
chemisorption: see adsorption
chemistry

abiotic oxygen: oxygen from non-life sources
abundances: relative amounts of each chemical element
acetylene: compound of two carbon and two hydrogen atoms
acidity: measure of the activity of hydrogen ions in a solution
adsorption: adhesion to a surface
aluminum: element, Al, atomic number 13
amine: type of compound containing nitrogen
ammonia: particular compound of nitrogen and hydrogen
atomic number: number of protons in an atomic nucleus
Avogadro's number: number of hydrogen atoms per gram
bulk density: total mass divided by total volume
calcium: element, Ca, atomic number 20
carbon: element, C, atomic number 6
carbon dioxide: compound of carbon atom and two oxygen atoms
carbon monoxide: compound of carbon and oxygen, one atom each
carbonate system: system governing water and CO2 in the presence of each other
carbonate-silicate cycle: long-term cycle that sequesters Earth carbon
chemical equilibrium: state where chemical makeup is unchanging
chemical tagging: using abundances to trace the origin of particular stars
chemodynamics: study of the dynamics of chemical reactions
CHNOPS: six common elements in biological molecules
CHON: four common elements in biological molecules
clathrate: crystal lattice with voids that can trap molecules
CO ladder: series of CO rotational spectral lines
diffusion: the spreading of particles toward an even distribution
electron shell: radius-level around an atomic nucleus at which electrons can orbit
element: class of atom based on its number of protons
energetic neutral atom: high-speed neutral atom
equilibrium condensation model: chemical model explaining solar system planet abundances
ethylene: compound of two carbon and four hydrogen atoms
fractionation: separation of one chemical mixture into others
fractionation factor: isotope-related ratio
geochemistry: the chemistry of the Earth, planets, and moons
glycine: smallest of the twenty common amino acids
helium: non-metallic element, He, atomic number 2
hydrocarbon: any compound of just carbon and hydrogen
hydrogen: most prominent element, atomic number 1
hydrogen cyanide: compound of hydrogen, carbon, and nitrogen, one atom each
hydrogen deuteride: hydrogen molecule with one deuterium atom
hydroxyl: one hydrogen atom and one oxygen atom bound together
ice: solid state of water
iron: metal, Fe, atomic number 26
lithium: metal, Li, atomic number 3
magnesium: element, Mg, atomic number 12
mass number: number of nucleons in an atomic nucleus
metallic hydrogen: a high-pressure state of hydrogen that is conductive
methane: compound of one carbon and 4 hydrogen atoms
methylidyne: compound of one carbon and one hydrogen atom
Milky Way chemical evolution: process of the development of metals in the Milky Way
mole: unit roughly the count of hydrogen atoms in a gram
molecular handedness: mirror-imaged variants of some molecules
neon: element, Ne, atomic number 10
nickel: metal, Ni, atomic number 28
nitrite: ion of a nitrogen atom and two oxygen atoms with extra electron
nitrogen: metal, N, atomic number 7
nucleon: proton or neutron
number density: number of objects per volume
oxidation state: number of electrons loaned out by an atom in an ionic bond
oxygen: element, O, atomic number 8
PAH emissions: infrared emission from polycyclic aromatic hydrocarbons in gas clouds
particle number: number of particles
phosphorus: metal, P, atomic number 15
photochemistry: study of the chemical effects of light
photodissociation: chemical reaction in which photons break chemical bonds
polycyclic aromatic hydrocarbon: hydrocarbons consisting of meshes of benzene rings
Population I: stars with substantial metallicity
Population II: stars with lower metallicity
Population III: stars with no metallicity
potassium/thorium ratio: indication of thermal history
radiolysis: similar to photodissociation from higher energy photons
reducing atmosphere: atmosphere lacking oxygen and other oxidizers
reduction potential: measure of a chemical species' tendency to acquire electrons
refractory material: material with high condensation temperature
relativistic effect: a substantial fraction of the speed of light
siderophile: material that dissolves in molten iron
signatures of formation: qualities of a body that suggest how it was formed
silicate: type of compound including silicon and oxygen
silicate weathering feedback: feedback mechanism stabilizing carbon in Earth atmosphere
silicon: metal, Si, atomic number 14
silicon monoxide: compound of silicon and oxygen, one atom each
sodium: metal, Na, atomic number 11
SPECTRE: an interactive spectrum analysis software package
stellar population: grouping of stars according to metallicity
sulfur: metal, S, atomic number 16
surface reaction: such as reactions between gas and adjacent liquid
titanium: metal, Ti, atomic number 22
titration: analyzing a chemical solution by color change
UCLCHEM: code to simulate the chemical reactions due to heat
volatile material: material with low condensation temperature
water: compound of oxygen atom and two hydrogen atoms
water activity: measure of partial vapor pressure of water

chemodynamics: study of the dynamics of chemical reactions
Chenab stream

Southern Stellar Stream Spectroscopic Survey: spectroscopic survey of seven southern-hemisphere stellar streams

CHEOPS: space telescope in development to measure radii of exoplanets
Cherenkov cone

Cherenkov radiation: radiation from the shock of a charged particle passing through a medium

Cherenkov detector: type of high energy photon or particle detector
Cherenkov gamma-ray telescope: see Cherenkov detector
Cherenkov radiation: radiation from the shock of a charged particle passing through a medium
- Cherenkov detector: type of high energy photon or particle detector
- GRAPES-3: Cherenkov telescope at Ooty, India
Cherenkov telescope (Cherenkov detector): type of high energy photon or particle detector
Cherenkov Telescope Array: ground gamma-ray telescope array in development
- Roque de los Muchachos Observatory: observatory at La Palma in the Canary Islands
Cherenkov Telescope Array Observatory (Cherenkov Telescope Array): ground gamma-ray telescope array in development
Chereul: see rare designator prefixes
Chern-Simons general relativity (Chern-Simons gravity): one type of modified general relativity
Chern-Simons gravity: one type of modified general relativity
Chern-Simons metric: see Chern-Simons gravity
- theoretical modified GR metric: metric devised to define modifications to GR
Chern-Simons modified general relativity (Chern-Simons gravity): one type of modified general relativity
Chern-Simons theory: see Chern-Simons gravity
Chi Draconis A

F-type star: spectral class of star a bit hotter than then Sun

chi-squared

chi-squared test: statistical significance test

chi-squared test: statistical significance test
Chicago Air Shower Array: see CASA-MIA
Chicagoland Observatory for Underground Particle Physics: see PICO experiment
Chicxulub crater: ancient giant impact crater under Mexico and the Gulf of Mexico
Chile

Atacama B-Mode Search: 2012-2014 survey of the CMB
Atacama Cosmology Telescope: 6-meter microwave survey telescope in Chile
Atacama Desert: Chilean high-altitude, dry plateau with numerous observatories
Atacama Large Millimeter Array: advanced millimeter-telescope array in Chile
Atacama Pathfinder Experiment: 12-meter submillimeter telescope in Chile
Atacama Submillimeter Telescope Experiment: 10-meter submillimeter telescope in Chile
AtLAST: concept for submillimeter survey telescope in Chile
BlackGEM: telescope array to follow up gravitational wave signals
Calán/Tololo Supernova Survey: late 1980s to early 1990s search to redshift 0.1
CCAT: 25-meter submillimeter telescope plan for Chile
Cerro Tololo Inter-American Observatory: NOIRLab observatory in Chile with Blanco telescope
Cherenkov Telescope Array: ground gamma-ray telescope array in development
CMB Stage-4: planned 2020s-generation of ground CMB observations
Cosmic Background Imager: radio telescope in Chile observing the CMB
Dark Energy Survey: survey aimed at mapping the universe's expansion
DECaLS: survey imaging part of SDSS footprint with DECam
ESO 3.6m Telescope: reflector telescope at La Silla
ESO Schmidt Telescope: 1 meter telescope in Chile with a wide field-of-view
European Extremely Large Telescope: 39-meter telescope under construction
European Southern Observatory: organization operating telescopes in the southern hemisphere
European Southern Observatory Very Large Telescope: four 8.2-meter optical telescopes in Chile that can act together
Fred Young Submillimeter Telescope: 6-meter submillimeter survey telescope under construction in Chile
Giant Magellan Telescope: 24.5 meter telescope under construction
HARPS: high-precision spectrograph for exoplanet searches
La Silla Observatory: Atacama-desert observatory run by ESO
La Silla Paranal Observatory: manages three ESO observatory-sites in Chile
Large Submillimeter Telescope: concept for a 50-meter submillimeter telescope in Chile
Las Campanas Observatory: observatory in southern Atacama Desert
Llano de Chajnantor Observatory: group of observatories on a high plateau of the Atacama Desert
Magellan Telescopes: pair of 6.5 m optical telescopes in Chile
Magellanic Clouds Photometric Survey: UBVI survey of the Magellanic Clouds
NANTEN2: millimeter telescope in Chile
New Technology Telescope: 3.58-meter reflector telescope in Chile
NGTS: survey of transits from Chile
NIRPS: near-infrared extension to HARPS spectrograph
Paranal Observatory: ESO Atacama observatory with ESO VLT
POLARBEAR: instrument to map CMB polarization
QUIET: survey to measure the polarization of the CMB
Rubin Observatory: 8-meter survey reflector telescope under construction in Chile
Simons Array: telescope array to map CMB polarization
Simons Observatory: CMB observatory on Atacama Desert
SOAR Telescope: 4.1 m reflector telescope in Chile
Sociedad Astronómica de Valparaíso y Viña del Mar: Chilean amateur astronomy society
Swedish-ESO Submillimetre Telescope: former 15 m radio telescope array in Chile
Swope Supernova Survey: survey of low-redshift Type Ia SN light curves
TRAPPIST: a ground-based automated transiting-planet finding telescope
University of Tokyo Atacama Observatory: observatory for a 6.5 m infrared telescope under construction
Víctor M. Blanco Telescope: 4 meter reflector telescope in Chile
VISTA: 4.1 meter telescope in Paranal Observatory in Chile
VLT Survey Telescope: survey telescope located at the VLT site

CHIME (Canadian Hydrogen Intensity Mapping Experiment): radio telescope mapping distant neutral hydrogen
- Dominion Radio Astrophysical Observatory: radio observatory in British Columbia, Canada
- NANOGrav: effort to detect gravitational waves through pulsar timing
CHIME/FRB: see Canadian Hydrogen Intensity Mapping Experiment
CHIME/FRB Catalog: see Canadian Hydrogen Intensity Mapping Experiment
CHIMERA: see Hale Telescope
CHIMERA: see atmospheric model
China

ARGO-YBJ Experiment: cosmic-ray/gamma-ray detector in Tibet
Beijing Astronomical Observatory: part of Chinese Academy of Sciences
CAS Space: Chinese commericial space-launch corporation
Chinese Academy of Sciences: Chinese national scientific organization
Chinese Pulsar Timing Array: group of pulsars timed by FAST
FAST: Arecibo-like 500 m telescope in China
LAMOST: Chinese telescope for spectroscopic surveys of stars and galaxies
LHAASO: gamma ray/cosmic ray observatory in China
Tianlai Project: 21-cm line intensity mapping project

Chinese

Einstein Probe: Chinese X-ray space observatory
HXMT: space X-ray observatory launched in 2017
Lunar-based Ultraviolet Telescope: Chinese ultraviolet telescope on the Moon
Satech-01: Chinese experimental spacecraft
Tiangong space station: Chinese manned space laboratory under construction in space
TianQin: proposed Chinese space mission to detect gravitational waves
Tianwen-1: active Chinese Mars rover/orbiter mission
XTP: past plan for a space X-ray telescope

Chinese Academy of Sciences: Chinese national scientific organization
Chinese Pulsar Timing Array: group of pulsars timed by FAST
CHIP: see Mauna Loa Solar Observatory
CHIPS: small satellite to investigate ISM plasma
CHIPSat (CHIPS): small satellite to investigate ISM plasma
chiral EFT: see effective field theory
chirality (molecular handedness): mirror-imaged variants of some molecules
Chiron

centaur: asteroid-like body orbiting among the outer planets

chirp: burst of signal rising or falling in frequency
chirp mass: a reduced-mass-like quantity that relates to gravitational waves
chloride: see geochemistry
chlorine

geochemistry: the chemistry of the Earth, planets, and moons

CHNOPS: six common elements in biological molecules
CHON: four common elements in biological molecules
chondrite: stony class of meteorites not modified by melting
- meteorite: rock found on Earth that is the remnant of a meteor
chondrule: see chondrite
- CAI: calcium/aluminum specs in chondrites
- meteorite: rock found on Earth that is the remnant of a meteor
chopper (chopping mirror): internal pivoting mirror to slightly change the instrument's aim
chopping: see chopping mirror
chopping mirror: internal pivoting mirror to slightly change the instrument's aim
CHORD: see Canadian Hydrogen Intensity Mapping Experiment
Christie: see rare designator prefixes
ChroMag: see Coronal Solar Magnetism Observatory
chromatic aberration: focusing different wavelengths differently
- aberration: types of flaws in telescope images
chromatic dispersion: see disperser
chromatic dispersion: see velocity dispersion
- refractive index: measure of how much a material slows down light
chromium

Ap star: peculiar type of A star

chromosphere: middle layer of the Sun's atmosphere
- Moreton wave: type of wave moving across the chromosphere
- stellar atmosphere: photosphere and above
- Sun surface features: features on the Sun's surface
Chromosphere Fine-Structure Study: see OSO 8
chromospheric activity index: measure of magnetic activity of a star's chromosphere
Chthonian: see atmospheric escape
Chthonian planet: see atmospheric escape
Chupina: see rare designator prefixes
CHXR: see rare designator prefixes
CHZ: see habitable zone
CI

carbon: element, C, atomic number 6
state of ionization: difference in an ion's electron count versus proton count

Ci: see rare designator prefixes
CIAO (Chandra Interactive Analysis of Observations): software for analyzing Chandra X-ray data
CIAO: see European Southern Observatory Very Large Telescope
CIAO: see Subaru Telescope
CIB (cosmic infrared background): widespread infrared radiation not associated with known sources
- CIBER: sounding-rocket survey of near-infrared background
- cosmic background radiation: electromagnetic radiation coming from every direction
- PEP: survey aimed at star formation in early times
CIBER: sounding-rocket survey of near-infrared background
CIBER-1 (CIBER): sounding-rocket survey of near-infrared background
CIBER-2: see CIBER
CIBR (cosmic infrared background): widespread infrared radiation not associated with known sources
CID: see Cosmic Evolution Survey
CIDA: see Stardust
CIG: initiative to produce Earth-science software
CIG: see rare designator prefixes
Cigar Galaxy (M82): nearby starburst galaxy
CII (C⁺): ionized carbon missing one electron
- carbon: element, C, atomic number 6
- state of ionization: difference in an ion's electron count versus proton count
CIII

state of ionization: difference in an ion's electron count versus proton count

Cimolai

ACe consortium: corporations contracted to construct E-ELT

CINDI (Coupled Ion-Neutral Dynamics Investigation): space weather investigation instruments on USAF spacecraft
CINEOS (Campo Imperatore Near-Earth Object Survey): survey of near-Earth objects
CIO (Catalog of Infrared Observations): collection of infrared observation data from numerous sources
CIRCE: see Gran Telescopio Canarias
Circinus Galaxy: nearest Seyfert galaxy
circle: see conic section
circle of latitude: circle around the Earth of points equidistant from a pole or the equator
circular polarization: see polarization
- circular polarization ratio: ratio of circular polarization handedness in reflected radar signal
circular polarization radar: see circular polarization ratio
circular polarization ratio: ratio of circular polarization handedness in reflected radar signal
circular symmetry: see axisymmetric
circumbinary disk: see circumstellar disk
circumbinary planet: exoplanet orbiting two stars
- Kepler-16b: exoplanet orbiting a binary star
circumgalactic medium: gas surrounding a galaxy
circumplanetary disk: disk of dust and gas around a planet
circumstellar disk: disk or ring shaped accumulation of matter around a star
- disk: rotating disk-shaped object such as disk galaxy or circumstellar disk
circumstellar envelope: shell-like cloud surrounding a star
- asymptotic giant branch: a second stage of helium burning in some stars
- planetary nebula: glowing gas shell ejected by a red giant
circumstellar habitable zone: see habitable zone
circumstellar material

superluminous supernova: stellar explosion larger than a supernova

circumstellar medium: see circumstellar envelope
cirrus (infrared cirrus): cirrus-cloud-like infrared emissions from dust, etc.
cirrus cloud

infrared cirrus: cirrus-cloud-like infrared emissions from dust, etc.

CIRS: see Cassini
- CEA Service d'Astrophysique: French national astrophysics research institute
CISCO: see Subaru Telescope
CIT: see rare designator prefixes
CITA (Canadian Institute for Theoretical Astrophysics): national research organization at University of Toronto
CIV: see ARGOS
CIVA: see Rosetta
CIZA: see rare designator prefixes
CK: see rare designator prefixes
CKM Matrix

quantum mixing: means by which one particle spontaneously changes to another

CKM Mixing

quantum mixing: means by which one particle spontaneously changes to another

CKS (California-Kepler Survey): follow-up to Kepler to determine stellar radii
CKS-COOL

California-Kepler Survey: follow-up to Kepler to determine stellar radii

CL (galaxy cluster): large group of galaxies gravitationally-bound to the group
CL: see rare designator prefixes
Cl: see Collinder Catalog
Cl: see stellar cluster
CLAES: see Upper Atmosphere Research Satellite
CLASH (Cluster Lensing and Supernova survey with Hubble): c2010 HST survey of galaxy cluster lensing
CLASS (Cosmic Lens All-sky Survey): 1990s/2000s radio survey aimed at gravitational lensing
- CRATES: catalog of 8.4 GHz data on radio sources
Class 0 YSO: see young stellar object
Class I YSO: see young stellar object
Class II YSO: see young stellar object
Class III YSO: see young stellar object
classical Cepheid: see Cepheid variable
classical gravitational field: see gravitational field
classical KBO: see Kuiper Belt
classical Kuiper Belt object: see Kuiper Belt
classical Lyot coronagraph (Lyot coronagraph): original coronagraph design
classical mechanics: see mechanics
- quantum field theory: reworking of quantum mechanics incorporating fields
- quantum mechanics: modern mechanical theory of small things, on the scale of atoms
- statistical mechanics: mechanical behavior based upon probability
classical nova: see nova
- V339 Delphini: 2013 nova showing lithium synthesis
classical T-Tauri star: see T-Tauri star
classification

Bautz-Morgan classification: morphology classification of galaxy clusters
dwarf galaxy classification: terms for of dwarf galaxy types
Fanaroff-Riley classification: a classification of the radio characteristics of radio sources
galaxy classification: morphological classification of galaxies
luminosity class: classification of size/luminosity of stars
Morgan classification: classification of galaxies by stellar spectrum and morphology
planet type: classification of a planet regarding some criteria
spectral class: overall classification of stars based upon spectral features
spectral type: classification of stars based upon spectral features
van den Bergh galaxy classification: galaxy classification variant including luminosity

classifier

balanced accuracy: average of true positive and negative rates

clathrate: crystal lattice with voids that can trap molecules
clathrate hydrate: see clathrate
Clay Telescope: see Magellan Telescopes
- CorMASS: near-infrared spectrograph
CLC (Lyot coronagraph): original coronagraph design
CLE: code to synthesize polarized emission lines of the solar corona
CLEAN: algorithm to extract usable images from interferometry-produced images
- CASA: software package for radio interferometry image generation
- dirty image: image that includes the distortions of the beam and sampling
clean image: see dirty image
- CLEAN: algorithm to extract usable images from interferometry-produced images
clearing the neighborhood: see dwarf planet
clearing the neighborhood: see planet
CLF (conditional luminosity function): function characterizing luminosity of galaxies with a given halo mass
climate

autoconversion rate: rate at which water changes from cloud droplets to new raindrops
general circulation model: climate model of a planet's atmosphere or ocean
HITRAN: spectroscopic parameters for modeling atmospheric optics
MarsWRF: Mars-oriented general circulation model
MITgcm: well-known general circulation model
one dimensional climate model: atmospheric model ignoring all horizontal motion
radiative forcing: difference between a planet's incoming and outgoing radiation
ROCKE-3D: rocky-planet-oriented general circulation model

climate change

earthshine: reflected and emitted electromagnetic radiation from Earth

climate model

atmosphere: gas surrounding astronomical object

CLIMB: see CHARA
Clio2: see MMT
close binary: see contact binary
close binary star: see binary star
- black hole merger: two black holes meeting and forming one
- ellipsoidal variable: binary star elongated by gravity
close stellar encounter: see flyby
closed magnetic field lines

curvature radiation: synchrotron-like radiation when particles follow curved field lines

closed universe: see critical density
closure phase

speckle masking: speckle suppression technique using a calculation of the bispectrum

cloud: higher-density region of space
cloud (galaxy cloud): substructure of a supercluster
- Cygnus-X: well-studied massive SF region
- Magellanic Bridge: hydrogen clouds joining the Magellanic Clouds
- Magellanic Stream: series of high-velocity clouds associated with the Magellanic Clouds
- Orion Molecular Cloud Complex: group of molecular clouds with star-forming regions
- Rho Ophiuchi Cloud Complex: nebula that is a nearby star-forming region
- Serpens Cloud: molecular cloud with SF regions
- Smith Cloud: high-velocity cloud on collision course with Milky Way
- Taurus Molecular Cloud 1: nearby star-forming region
- W51: cloud complex radio source
cloud droplet: see autoconversion rate
cloud fragmentation: clumping in clouds due to gravitational instability
cloud mass function: see dense core mass function
cloud of galaxies (galaxy cloud): substructure of a supercluster
cloud type

Bok globule: dense molecular cloud
bright nebula: cloud that gives off or reflects light
dark nebula: cloud that obscures stars behind it
dense core: dense molecular cloud
emission nebula: nebula that emits light such as an HII region or PN
evaporating gas globule: very small dense cloud of hydrogen and dust
filament: linear volume of high molecular gas density within a galaxy
giant molecular cloud: interstellar gas cloud with molecules, thousands of solar masses
HI region: cloud of neutral atomic hydrogen
high-velocity cloud: fast-moving clouds in galactic halos
HII region: cloud of partially-ionized atomic hydrogen
infrared cirrus: cirrus-cloud-like infrared emissions from dust, etc.
infrared dark cloud: molecular cloud not emitting nor transmitting infrared
intergalactic HI cloud: cloud of HI not within any galaxy
Lyman-alpha blob: Lyman-alpha emitting cloud larger than a galaxy
molecular cloud: interstellar gas cloud that includes molecules
nebula: cloud of dust and gas
photodissociation region: cloud of partially-ionized atomic hydrogen
planetary nebula: glowing gas shell ejected by a red giant
protogalaxy: gas cloud forming a galaxy
radio halo: type of diffuse radio source at the center of a galaxy cluster
radio phoenix: region of galaxy cluster from which radio is emitted a subsequent time
radio relics: clouds from past galaxy emitting radio synchrotron radiation
reflection nebula: nebula made visible by light it scatters from nearby stars
star-forming region: area forming stars and/or ready for star formation
Strömgren sphere: sphere of ionized hydrogen around an OB star

clouds

AMUSE²: survey of ELANs
carbon monoxide: compound of carbon and oxygen, one atom each
cloud fragmentation: clumping in clouds due to gravitational instability
dense core mass function: function describing range of masses of dense cores
Dickel-Wendker-Bieritz Catalog: list of HII regions in the Cygnus X star-forming region
hydrogen deuteride: hydrogen molecule with one deuterium atom
hydroxyl: one hydrogen atom and one oxygen atom bound together
interstellar astrophysics: astronomy of the ISM including dust and clouds
interstellar medium: matter within a galaxy between star systems
ionization correction factor: relations between ion abundances and element abundances
Jeans length: critical radius above which gravity will collapse a cloud
kinematic distance: distance to objects within Milky Way based on radial velocity
Lockman hole: region of sky with little Milky-Way neutral hydrogen
molecular cloud turbulence: observed turbulence in molecular clouds
molecular hydrogen dissociation front: point in a gas cloud where it is hot enough to dissociate hydrogen
pulsar wind nebula: type of nebula generated by a young pulsar
Sharpless Catalog: catalog of HII regions found on Palomar plates
striae: parallel ridges
The H2O Southern Galactic Plane Survey: survey of molecular clouds in the galactic plane
tracer: chemical whose detection indicates the presence of something else
virial parameter: calculated quantity showing whether a cloud is gravitationally bound

Cloudy: code to model the effect of gas and plasma on spectra
CLS: see rare designator prefixes
clump: see dense core mass function
clump giant: see red clump
clump mass function: see dense core mass function
CLUPI: see Rosalind Franklin
CLUST: see rare designator prefixes
cluster (galaxy cluster): large group of galaxies gravitationally-bound to the group
cluster (stellar cluster): group of stars apparently formed by a single cloud
cluster dark matter halo: see dark matter halo
cluster environment: see galaxy environment
cluster fitting (main sequence fitting): cluster star distance determined through fitting with the H-R diagram
Cluster Lensing and Supernova survey with Hubble: c2010 HST survey of galaxy cluster lensing
cluster radius: radius of a galaxy cluster
CM (barycenter): center of mass of two orbiting bodies
CM (color-magnitude diagram): graph plotting color index to magnitude
CM: see rare designator prefixes
CMA (cold mass accretion): stellar accretion through an accretion disk
CMa Dwarf (Canis Major Dwarf Galaxy): small irregular galaxy in the Local Group
CMa Overdensity (Canis Major Dwarf Galaxy): small irregular galaxy in the Local Group
CMB (cosmic microwave background): microwave radiation coming from every direction
- ACBAR: instrument used in a CMB survey
- angular power spectrum: method of characterizing the CMB
- anisotropy: directional-dependence such as temperature variation around the CMB
- ARCADE: balloon-borne centimeter-wavelength surveyor
- Archeops: balloon-borne 1.3 m submillimeter telescope
- Arcminute Microkelvin Imager: pair of microwave arrays
- Atacama B-Mode Search: 2012-2014 survey of the CMB
- Atacama Cosmology Telescope: 6-meter microwave survey telescope in Chile
- BICEP2: survey to measure the polarization of the CMB
- BOOMERanG: 1990s-2000s balloon-borne 1.3-meter millimeter telescope
- CAPMAP: early 2000s array that surveyed CMB polarization
- CMB anisotropies: variations in the spectrum of the CMB
- CMB dipole: CMB variation due to our velocity
- CMB lensing: gravitational lensing of the CMB
- CMB polarization: effects of scattering and lensing on the CMB
- CMB Stage-4: planned 2020s-generation of ground CMB observations
- CMB surveys: efforts studying the CMB
- CMBFAST: software to calculate CMB anisotropies
- cold spot: unusually colder spot in the CMB
- Cosmic Anisotropy Telescope: 1990s interferometer to measure CMB variations
- Cosmic Background Explorer: 1989 satellite for surveying the CMB
- Cosmic Background Imager: radio telescope in Chile observing the CMB
- cosmic background radiation: electromagnetic radiation coming from every direction
- cosmic variance: density variation on a cosmic scale
- COSMOSOMAS: 1990s-2000s microwave survey
- DASI: 2000-2003 South Pole CMB telescope
- destriping: removing streak-like noise from images
- diffusion damping: a damping process within the plasma during recombination
- EBEX: balloon-based CMB polarization survey
- inflation: theorized rapid expansion of the very early universe
- initial fluctuations: early universe density variations leading to current universe
- LiteBIRD: planned spacecraft to map CMB polarization
- LSPE-STRIP: CMB survey telescope in Canary Islands
- LSPE-SWIPE: plan for a balloon-based CMB polarization survey
- MAXIMA: 1998-1999 balloon-borne 1.3-meter millimeter telescope
- missing baryon problem: standard theory suggests more baryonic matter than observed
- multipole expansion: series expansion of a function over the surface of a sphere
- PIXIE: satellite-concept to to survey CMB polarization
- Planck: microwave telescope in space
- POLARBEAR: instrument to map CMB polarization
- polarization modes: curl- and divergent-like components of CMB polarization patterns
- primordial gravitational waves: gravitational waves formed in the early universe
- QMAP: mid 1990s balloon-based CMB survey
- QUaD: survey to measure the polarization of the CMB
- QUBIC: survey measuring the polarization of the CMB
- QUIET: survey to measure the polarization of the CMB
- QUIJOTE: survey to measure the polarization of the CMB
- recombination: time when the universe's ionized hydrogen atoms neutralized
- reheating: theorized increase in temperature after cosmological inflation
- RELIKT-1: instrument on 1980s Soviet satellite to view the CMB
- Sachs-Wolfe effect: gravitational redshift of the CMB
- Saskatoon: 1990s survey to measure CMB anisotropy
- sigma-8 tension: Lambda CDM anomaly regarding matter fluctuation
- Simons Array: telescope array to map CMB polarization
- South Pole Telescope: a millimeter/microwave telescope at South Pole
- SPIDER: 2015 balloon-borne observatory to observe CMB polarization
- Sunyaev-Zel'dovich Array: array of eight 3.5 meter microwave telescopes
- Sunyaev-Zel'dovich effect: type of distortion of the CMB
- surface of last scattering: sphere around us from which CMB photons are just reaching us
- Taurus: balloon-borne polarimeter to study the CMB
- Tenerife Experiment: 1980s-1990s survey of CMB anisotropies
- time-ordered data: observation data arranged by the time it was received
- TopHat: 2001 balloon -based CMB survey
- Very Small Array: radio interferometer in Canary Islands
- Wilkinson Microwave Anisotropy Probe: spacecraft that measured variations in the cosmic background radiation
- Yuan-Tseh Lee Array: microwave interferometer in Hawaii
- Zel'dovich approximation: model of the formation of cosmological structure
CMB anisotropies: variations in the spectrum of the CMB
- baryon acoustic oscillations: density fluctuations stemming from acoustic waves in the early universe
- CMB dipole: CMB variation due to our velocity
- primordial gravitational waves: gravitational waves formed in the early universe
CMB cold spot (cold spot): unusually colder spot in the CMB
CMB dipole: CMB variation due to our velocity
CMB dipole: see CMB anisotropies
CMB experiments (CMB surveys): efforts studying the CMB
CMB foreground: see cosmic microwave background
- C-BASS: 6 cm survey of the entire sky
CMB lensing: gravitational lensing of the CMB
CMB polarization: effects of scattering and lensing on the CMB
- PIXIE: satellite-concept to to survey CMB polarization
CMB Stage-4: planned 2020s-generation of ground CMB observations
CMB surveys: efforts studying the CMB
CMB weak lensing: see weak lensing
CMB-S4 (CMB Stage-4): planned 2020s-generation of ground CMB observations
CMBFAST: software to calculate CMB anisotropies
CMBR (cosmic microwave background): microwave radiation coming from every direction
CMC (Carlsberg Meridian Catalogue): series of astrometric catalogs from 19th century on
CMD (color-magnitude diagram): graph plotting color index to magnitude
CMDM: see MMX
CME (coronal mass ejection): mass of plasma ejected from the Sun
- DISCOVR: space weather satellite
- ejection: forcing or throwing something out
- ESA Vigil: plan for space-weather warning satellite at L5
- flux rope: rope-shaped structure in magnetic fields associated with coronal mass ejections
- Forbush decrease: decrease in cosmic rays after a coronal mass ejection
- solar energetic particle: high-energy particles from the Sun
- solar eruption: sudden brightening of the Sun
- solar particle event: episode of higher velocity solar wind
- solar storm: general term for events on the Sun
- space weather: varying conditions in space affecting Earth and humans
- Sun surface features: features on the Sun's surface
- UVSC Pathfinder: instrument to observe the Sun
CMF (conditional stellar mass function): function characterizing galaxies within a halo of a given mass
CMF (dense core mass function): function describing range of masses of dense cores
CMFGEN: RT code designed to handle significant stellar wind
CMOS sensor: see CCD
CN: see New General Catalogue
CN: see nova
Cn: see rare designator prefixes
CN Leonis (Wolf 359): nearby red dwarf
CNB (cosmic neutrino background): low-energy neutrinos left over from early universe
- cosmic background radiation: electromagnetic radiation coming from every direction
CNES (Centre national d'ètudes spatiales): French space agency
- COROT: observatory-satellite to look for transiting exoplanets and stellar oscillations
CNM: see HI region
CNM: see interstellar medium
CNN (convolutional neural network): type of image processing software
CNO: see CNO cycle
CNO cycle: fusion reaction chain turning hydrogen and nitrogen into helium and nitrogen
- hydrogen burning: any fusion reaction starting with hydrogen
- oxygen: element, O, atomic number 8
- proton-proton chain: type of fusion reaction chain turning hydrogen into helium
CNR (Consiglio Nazionale delle Ricerche): Italian national research organization.
CNRS (Centre national de la recherche scientifique): French scientific research organization
- Astronet: European astronomy consortium
CNSR (Comet Nucleus Sample Return): concept study for comet mission
CnuB (cosmic neutrino background): low-energy neutrinos left over from early universe
CO (carbon monoxide): compound of carbon and oxygen, one atom each
CO (compact object): dense astronomical body such as white dwarf or denser
CO: see rare designator prefixes
- AIM-CO: survey of CO from star-forming epoch
- alpha CO: ratio of CO emissions to H₂
- CARMA EDGE: survey CO-mapping galaxies
- CO ladder: series of CO rotational spectral lines
- CO to H₂ factor: assumed ratio between observed CO emission lines and H₂ mass
- COLD GASS: survey of CO in nearby large galaxies
- COMAP: high frequency radio telescope to map CO
- COPSS: survey of CO from star forming epoch
- EXCLAIM: planned balloon-borne 70-cm telescope with spectrometers
- Millimeter-wave Intensity Mapping Experiment: project to map CO and [CII]
- PAWS: survey of GMCs in M51a
- PHIBSS: survey of CO in distant galaxies
CO ice line: see snow line
CO J ladder (CO ladder): series of CO rotational spectral lines
CO ladder: series of CO rotational spectral lines
CO Legacy Database for GASS (COLD GASS): survey of CO in nearby large galaxies
- GALEX Arecibo SDSS Survey: HI survey of many galaxies
CO Mapping Array Pathfinder: see COMAP
CO Mapping Array Project (COMAP): high frequency radio telescope to map CO
CO rotational ladder (CO ladder): series of CO rotational spectral lines
CO to H₂ factor: assumed ratio between observed CO emission lines and H₂ mass
CO(1-0): see CO ladder
CO(2-1): see CO ladder
CO(3-2): see CO ladder
CO(4-3): see CO ladder
CO(5-4): see CO ladder
CO(6-5): see CO ladder
CO(7-6): see CO ladder
CO₂ (carbon dioxide): compound of carbon atom and two oxygen atoms
CO₂ ice line: see snow line
coalescence: merging together, becoming one thing
COAST: optical interferometer in England
COAST: see Australian Square Kilometre Array Pathfinder
- Mullard Radio Astronomy Observatory: radio observatory near Cambridge, UK
- optical interferometer: interferometer of visible light
coastal Kelvin wave: see Kelvin waves
COB (cosmic optical background): widespread optical radiation not associated with known sources
COBE (Cosmic Background Explorer): 1989 satellite for surveying the CMB
COCO (Copernicus Complexio): high-resolution cosmological N-body simulation
COCONUTS: survey to image companions of stars
COCONUTS-2b

COCONUTS: survey to image companions of stars

CoD: see Bonner Durchmusterung Catalog
code: astrophysical modeling computer program
- AREPO: cosmology simulation using moving mesh technique
- AstroBEAR: MHD simulation system
- ATLAS Stellar Model: computer model of a stellar photosphere
- ATMO: atmospheric code for exoplanets and brown dwarfs
- batman: code to calculate model transit lightcurves
- BPASS: evolution and population synthesis code for binary stars
- BSE: a code to model the evolution of a binary star system
- BT-Settl: model atmosphere of small stars and brown dwarfs
- Castro: hydrodynamics simulation software
- ChaNGa: cosmological-simulation project active since circa 2015
- CLE: code to synthesize polarized emission lines of the solar corona
- Cloudy: code to model the effect of gas and plasma on spectra
- CMFGEN: RT code designed to handle significant stellar wind
- COMPAS: SPS code for compact object binaries
- DISORT: simulation of radiative transfer in an atmosphere
- DustEM: code to calculate dust extinction and emission
- dynesty: code for comparing the applicability of multiple models
- Enzo: hydrodynamic simulation system
- EXOFAST: code to match model parameters with exoplanet observation data
- Fastest Fourier Transform in the West: code library implementing efficient FFT
- FLASH: hydrodynamic simulation system
- FORNAX: hydrodynamics simulation software
- FSPS: code library for stellar population synthesis
- GalDNA: code to estimate chemical abundances from galaxy emission lines
- Gasoline: an SPH code
- GR1D: core collapse supernova simulation in 1D with GR
- GYRE: a stellar oscillation code
- HERMIT: code to carry out N-body simulations
- Hyperion: Monte Carlo radiative transfer code
- iSALE: code modeling the shock physics of impacts
- LA-COMPASS: MHD-capable hydrodynamic code
- MagIC: numerical code to for fluid dynamics including dynamos
- MATCH: SFH code
- MERCURY: code to carry out N-body simulations
- minkasi: code for processing MUSTANG-2 data
- MOCCA: code to model the evolution of stellar clusters
- NBODY: code to carry out N-body simulations
- PHOENIX stellar model: computer model of a stellar photosphere
- PICASO: rt code specifically for exoplanet transmission spectroscopy
- PLUTO Code: fluid-dynamic simulation code
- PROMETHEUS/VERTEX: hydrodynamic simulation system
- RADEX: radiative transfer code
- RAMSES: hydrodynamic simulation system
- RASCALL: efficient code to locate suspected molecular lines
- REBOUND: code to carry out N-body simulations
- RODEO: code for 2D disk simulation
- SIMBA: galaxy formation simulation code
- SpEC: code to solve general relativity problems
- SPOCK: code to determine stability of orbits
- STARFORGE: star formation simulation code
- STarSPot: code to model starspots
- StarTrack: stellar population synthesis code
- Tau-REx: spectral line retrieval code for exoplanet atmospheres
- TSUNAMI: few-body code
- Turtlebeach: radiative transfer code
- TYCHO: stellar evolution code
- UCLCHEM: code to simulate the chemical reactions due to heat
Code for Anisotropies in the Microwave Background: see CMBFAST
code type

cosmological simulation: simulation of the history of the universe
N-body simulation: simulation of many objects gravitationally-bound to each other
stellar population synthesis code: software to perform stellar population synthesis

codes

Astrophysics Source Code Library: collection of astrophysics programs

CODEX: see European Extremely Large Telescope
CoDICE: see IMAP
coefficient

absorption coefficient: measure of how much light a substance absorbs
J₂: geopotential coefficient regarding a planet's oblateness

coeval: the same age
coherence: see coherent light
coherent dense core: see dense core
coherent light: beam of light at a single frequency
COHSI: see United Kingdom Infrared Telescope
CoKu Tau: see rare designator prefixes
Col: see Collinder Catalog
Col-OSSOS: see Outer Solar System Origins Survey
Colca Valley

TAMBO: concept for neutrino detector in valley in Peru

cold dark matter: one of three classes of "particle dark matter" theory
cold dark matter: see dark matter
- fuzzy dark matter: concept of extremely light dark matter particles
- sub-GeV dark matter: a more-massive type of CDM
cold disk accretion: see AGN accretion
cold gas: gas cool enough to form galaxies and stars
- galaxy strangulation: galaxy star formation stopped by a lack of incoming gas
COLD GASS: survey of CO in nearby large galaxies
- GALEX Arecibo SDSS Survey: HI survey of many galaxies
cold mass accretion: stellar accretion through an accretion disk
cold neutral medium: see HI region
cold neutral medium: see interstellar medium
cold pixel: see hot pixel
cold spot: unusually colder spot in the CMB
cold start: see giant planet formation
- planet formation: process by which planets form
cold trap: layer of atmosphere that prevents a gas from escaping by freezing it
Collaboration for Astronomy Signal Processing and Electronics Research (CASPER): initiative to design radio-astronomy instruments
collapsar: neutron star or stellar black hole
collapsar model: see superluminous supernova
- collapsar: neutron star or stellar black hole
collecting area: cross-sectional area over which a telescope receives EMR
- spectral flux density: flux or power of radiation per unit area per unit wavelength
collection area (collecting area): cross-sectional area over which a telescope receives EMR
colliding-wind binary: see WR 140
collimate: see collimator
collimated light: see collimator
collimator: device to align beams of light
Collinder: see Collinder Catalog
Collinder 50 (Hyades Cluster): nearest open cluster
Collinder Catalog: 1930s catalog of 471 open clusters
collision: see heating
- collisional broadening: line broadening due to nearby particles
- galaxy merger: combination of galaxies upon collision
- Landau damping: type of damping of waves that occurs in thin plasma
collision cross section: see cross section
collisional: see stellar dynamics
- globular cluster: spherical group of stars orbiting a galaxy
collisional broadening: line broadening due to nearby particles
collisional broadening: see line broadening
collisional cascade (Kessler syndrome): low-Earth-orbit debris growing out of control
collisional erosion: removing a body's substance through impacts
collisional growth: see planet formation
collisionless Boltzmann equation: see Vlasov-Poisson equation
collisionless damping: see Landau damping
collisionless plasma: see plasma
COLOR: see Copernicus Complexio
color (color index): a number that characterizes the color of an object
- color-color diagram: means of comparing characteristics of stars
- color-magnitude diagram: graph plotting color index to magnitude
- color-period diagram: means of comparing periods of stars at various wavelengths
- cross dispersion spectrograph: echelle spectrograph with additional disperser crosswise to the first
- g-r color: difference between SDSS g' and r' magnitudes
- griz photometric system: photometric system designed for electronic sensors
- imaging Fourier transform spectroscopy: Michelson-interferometer-based imaging spectroscopy
- imaging spectrometer: device to capture spectrum point-by-point of an image
- integral field spectrograph: spectrograph that captures images
- integral field unit: instrument to allow a spectrograph to capture data over a 2D field
- JHK photometric system: system to classify stars according to near-infrared colors
- MKO photometric system: 2000s system covering near infrared
- multi-object spectrograph: device to record the spectrum of multiple targets simultaneously
- passband: range of electromagnetic wavelengths that a filter allows
- photometric system: specification of a set of filters/passbands
- sensitivity function: function of wavelength giving the sensitivity of an instrument
- spectrograph: device to record the spectrum of incoming light
- spectrography: charting the strengths of different electromagnetic wavelengths
- spectrometer: device to measure light by wavelength across its spectrum
- spectrometry: measuring the strengths of different electromagnetic wavelengths
- spectroscope: device to study the spectrum of incoming light
- spectroscopy: measurement of light with various electromagnetic wavelengths
- Strömgren photometric system: four-color photometric system devised in 1950s
- UBV photometric system: commonly-cited photometric system for describing stars' colors
- ugriz photometric system: photometric system used for SDSS
- UVJ diagram: diagram to identify star formation in distant galaxies
color charge: see strong force
color excess: see color index
color excess: see reddening
color index: a number that characterizes the color of an object
color temperature: temperature-measure of a source based on a color index
- color index: a number that characterizes the color of an object
- effective temperature: temperature of an equivalent black body in terms of total radiation
- temperature: measure of hotness/coldness of matter
color-color diagram: means of comparing characteristics of stars
color-magnitude diagram: graph plotting color index to magnitude
color-period diagram: means of comparing periods of stars at various wavelengths
Colorado Ultraviolet Transit Experiment (CUTE): CubeSat ultraviolet space telescope
Colossus Telescope: concept for a 50-meter telescope using interferometry
Colours of the Outer Solar System Origins Survey: see Outer Solar System Origins Survey
column density: measure of the matter through which EMR is passing
- particle number: number of particles
column mass density: see column density
column number density: see column density
COMA (Carbon Monoxide Mapping Array): planned experiment to observe epoch of reionization
Coma

Stardust: space mission that collected and returned comet coma dust

coma: aberration where points of light show a tail
coma: see comet
Coma Berenices

Milky Way subgroup: the Milky Way and its satellites

Coma Cluster

Coma Supercluster: nearby supercluster
galaxy cluster: large group of galaxies gravitationally-bound to the group

Coma Filament: see galaxy filament
Coma Supercluster: nearby supercluster
- Great Wall: large slab of galaxies
Coma Wall (Great Wall): large slab of galaxies
COMAP: high frequency radio telescope to map CO
- Carbon Monoxide Mapping Array: planned experiment to observe epoch of reionization
COMAP pathfinder: see COMAP
comatic aberration (coma): aberration where points of light show a tail
Combined Array for Research in Millimeter-wave Astronomy: former array of radio telescopes in eastern California
Combined Coudé Laboratory: see European Southern Observatory Very Large Telescope
combined differential photometric precision: calculated relation of photometric variation to SNR
Combined Radio All-sky Targeted Eight-GHz Survey (CRATES): catalog of 8.4 GHz data on radio sources
Combined Release and Radiation Effects Satellite: 1990s satellite investigating Earth's magnetosphere
ComCam: see Giant Magellan Telescope
comet: Sun-orbiting object with coma and possible tail
- 67P/Churyumov-Gerasimenko: comet visited by Rosetta space mission
- C/2014 UN₂₇₁: very large comet discovered at a distance
- Comet Shoemaker-Levy 9: comet that collided with Jupiter in 1994
Comet Astrobiology Exploration Sample Return (CAESAR): planned space mission to return a sample of a comet
Comet Bernardinelli-Bernstein (C/2014 UN₂₇₁): very large comet discovered at a distance
Comet Galaxy: unique spiral galaxy in cluster Abell 2667
Comet Giacobini-Zinner

International Cometary Explorer: 1980s space mission flying by comets

Comet Halley: see comet
- Giotto: 1980s space mission carrying out a Comet Halley flyby
- International Cometary Explorer: 1980s space mission flying by comets
- long-period comet: comet with an orbital period of more than 200 years
- Pioneer Venus Orbiter: NASA Venus probe launched 1978
- SPARTAN: series of astronomy satellites launched/retrieved by Space Shuttles
Comet Nucleus Sample Return: concept study for comet mission
Comet P/Shoemaker-Levy 9 (Comet Shoemaker-Levy 9): comet that collided with Jupiter in 1994
comet planet: planet with some characteristics of a comet
Comet Rendezvous Asteroid Flyby: 1980s/1990s NASA comet exploration plan
Comet Shoemaker-Levy

comet: Sun-orbiting object with coma and possible tail

Comet Shoemaker-Levy 9: comet that collided with Jupiter in 1994
cometary globule: see Bok globule
cometary hydrogen cloud: see comet
cometary nebula: see reflection nebula
- cloud: higher-density region of space
- Parsamian Nebula Catalog: 1965 list of nebulae
comets

American Workshop on Cometary Astronomy: renamed to be international, i.e., IWCA
asteroid: minor planet without comet characteristics
CAESAR: planned space mission to return a sample of a comet
Catalogue of Cometary Orbits: comet catalog updated since 1970s
centaur: asteroid-like body orbiting among the outer planets
Comet Nucleus Sample Return: concept study for comet mission
Committee for Small-Body Nomenclature: early 2000s IAU division since replaced by WG-SBN
Deep Impact: mission to create and observe an impact with a comet
Hills Cloud: cloud of comets and minor planets around the solar system
International Comet Quarterly: journal regarding comets
International Cometary Explorer: 1980s space mission flying by comets
International Halley Watch: initiative to coordinate observation of Halley's Comet in 1986
International Monitoring Programs for Asteroid and Comet Threat: 1999 IAU-sponsored conference in Italy
International Workshop on Cometary Astronomy: occasional meeting
Kuiper Belt: further part of solar system beyond Neptune
long-period comet: comet with an orbital period of more than 200 years
Meeting of European Planetary & Cometary Observers: 1990s planet/comet observer meetings
minor planet: lesser solar system body without comet characteristics
Oort Cloud: cloud of distant comets surrounding the solar system
Oort Cloud Object: object in Oort Cloud such as a comet
Rosetta: space probe that visited a comet
solar system object: the Sun, solar system planets, minor planets, comets, and moons
Stardust: space mission that collected and returned comet coma dust
striae: parallel ridges
The Amateur Sky Survey: amateur comet and variable-star search survey
Uppsala-ESO Survey of Asteroids and Comets: 1990s comet and asteroid survey

COMICS: see Subaru Telescope
commensal mode: telescope usage that accomplishes multiple observations simultaneously
Commensal Real-time ASKAP Fast Transients survey: see Australian Square Kilometre Array Pathfinder
commensurability: see orbital resonance
Commissariat à l'énergie atomique et aux énergies alternatives

CEA Service d'Astrophysique: French national astrophysics research institute

Committee for Small-Body Nomenclature: early 2000s IAU division since replaced by WG-SBN
Committee on Space Research: international collaboration established by International Council for Science
Committee on the Status of Women in Astronomy: AAS committee
Common Astronomy Software Application (CASA): software package for radio interferometry image generation
common envelope: binary star system surrounded by a single gas cloud
common envelope: see post-common-envelope binary
common envelope binary: see common envelope
common envelope binary event: see common envelope
common proper motion: see proper motion
common-envelope binary: see post-common-envelope binary
common-envelope-binary event: see post-common-envelope binary
Commonwealth Scientific and Industrial Research Organisation

Australia Telescope Compact Array: radio telescope in eastern Australia

Community Science and Data Center: see NOIRLab
community TOI: see Transiting Exoplanet Survey Satellite
comoving coordinates: see comoving units
comoving density of star formation: see star formation rate
comoving distance: see comoving units
comoving horizon (particle horizon): furthest point from which light can reach us
comoving SFR density: see star formation rate
comoving SFRD: see star formation rate
comoving space density: see comoving units
comoving speed: see comoving units
comoving star formation rate density: see star formation rate
comoving units: units of measure that incorporate the scale factor
comoving volume: see comoving units
CoMP: see Mauna Loa Solar Observatory
compact binary: see binary star
compact galaxy: see dwarf galaxy
compact group: see galaxy group
- Stephan's Quintet: five galaxies grouped in the sky
compact HII region: see HII region
compact object: dense astronomical body such as white dwarf or denser
- collapsar: neutron star or stellar black hole
compact object binary

galactic binary: system of two object co-orbiting within the Milky Way

compact object merger: see compact object
Compact Object Mergers: Population Astrophysics and Statistics (COMPAS): SPS code for compact object binaries
compact objects

COMPAS: SPS code for compact object binaries
galactic binary: system of two object co-orbiting within the Milky Way

Compact Objects with ASKAP: Surveys and Timing: see Australian Square Kilometre Array Pathfinder
compact star (compact object): dense astronomical body such as white dwarf or denser
compact stellar nucleus: see stellar nucleus
companion (binary companion): one of the two stars of a binary star
companion star (binary companion): one of the two stars of a binary star
comparator: device to compare the position of objects on plates
COMPAS: SPS code for compact object binaries
COMPLETE Survey: survey of star forming regions
Completely Autonomous Service Telescope

COAST: optical interferometer in England

completeness: measure of how many of a survey's objects of a certain magnitude have been detected
completeness limit: see completeness
complex: see molecular cloud
complex amplitude: see amplitude
complex conjugate

Majorana particle: theoretical particle that is its own antiparticle

complex crater: crater with central high-point
complex number: type of number that can be the square root of a negative number
complex number system: see complex number
complex numbers

Euler's formula: formula relating exponentials to trigonometric functions

complex plane: see complex number
complex visibility: see visibility
composite boson: see particle
composite remnant: see supernova remnant
composite-spectrum binary (spectrum binary): binary star detectable because its spectrum looks like that of two stars
compound

acetylene: compound of two carbon and two hydrogen atoms
amine: type of compound containing nitrogen
ammonia: particular compound of nitrogen and hydrogen
carbon dioxide: compound of carbon atom and two oxygen atoms
carbon monoxide: compound of carbon and oxygen, one atom each
ethylene: compound of two carbon and four hydrogen atoms
glycine: smallest of the twenty common amino acids
hydrocarbon: any compound of just carbon and hydrogen
hydrogen cyanide: compound of hydrogen, carbon, and nitrogen, one atom each
hydrogen deuteride: hydrogen molecule with one deuterium atom
hydroxyl: one hydrogen atom and one oxygen atom bound together
methane: compound of one carbon and 4 hydrogen atoms
methylidyne: compound of one carbon and one hydrogen atom
nitrite: ion of a nitrogen atom and two oxygen atoms with extra electron
polycyclic aromatic hydrocarbon: hydrocarbons consisting of meshes of benzene rings
silicate: type of compound including silicon and oxygen
silicon monoxide: compound of silicon and oxygen, one atom each

compound lens: see chromatic aberration
compound lens: see spherical aberration
Compressible Astrophysics (Castro): hydrodynamics simulation software
COMPTEL: see Compton Gamma Ray Observatory
Compton camera (Compton telescope): type of gamma ray telescope for 0.75-30 MeV range
Compton cooling: see Compton scattering
Compton effect: see Compton scattering
Compton Gamma Ray Observatory: 1990s space observatory for gamma ray observation
- General Coordinates Network: service reporting transients
Compton hump: see Compton reflection
Compton optical depth: see Thomson optical depth
Compton parameter: see Compton scattering
Compton reflection: recognizable emission due to a gas or plasma's Compton scattering
Compton scattering: photon collision with a charged particle that emits a different photon
- Compton reflection: recognizable emission due to a gas or plasma's Compton scattering
- Compton telescope: type of gamma ray telescope for 0.75-30 MeV range
- electron scattering: any process that changes the course of an electron
- Klein-Nishina formula: formula for the effects of electrons scattering photons
- non-thermal emission: EMR not due to a body's heat
- Penrose Compton scattering: type of Compton scattering within a black hole's ergosphere
- scintillator: instrument part designed to respond to high-energy photons
- synchrotron self-Compton: charged particle cloud scattering its own synchrotron-produced photons
Compton telescope: type of gamma ray telescope for 0.75-30 MeV range
Compton thick: see Thomson optical depth
Compton upscattering: see Compton scattering
Compton wavelength: lower bound on a particle's possible de Broglie wavelength
Compton Y-parameter: see Compton scattering
Comptonization: see Compton scattering
computation: see numerical methods
- adaptive mesh refinement: numerical modeling method balancing detail with tractability
- basis function: one of a set of functions used to approximate a function of interest
- Bernstein polynomial: polynomial form capable of producing arbitrary shapes
- Centre for Astrophysics and Supercomputing: research center at Swinburne University, Australia
- CIG: initiative to produce Earth-science software
- cosmological simulation: simulation of the history of the universe
- discontinuous Galerkin method: computational method for PDEs handling discontinuities
- fast Fourier transform: efficient algorithm for calculating a discrete Fourier transform
- finite difference method: means of estimating calculus and differential equation solutions
- finite element method: computational method for PDEs suited to physical problems
- finite volume method: computational method for PDEs especially suited to fluid dynamics
- flux reconstruction: numerical approach emphasizing joining the subdivisions
- Godunov scheme: computational fluid dynamics method
- GPU Supercomputer for Theoretical Astrophysics Research: supercomputer at Swinburne University
- high resolution shock capture: method of modeling shock waves
- Hough transform: algorithm used in image processing
- Krylov subspace method: efficient method of numerically solving sets of linear equations
- lattice Boltzmann method: computational fluid dynamics method treating the fluid as particles
- machine learning: use of programs that extract their algorithms from data
- Markov chain Monte Carlo: model technique to approximate multi-dimensional integrals
- mass shell: conceptual volume of mass shaped like a hollow sphere
- Message Passing Interface: mechanism for passing data between processors of a multiprocessor
- neural network: computer program structure inspired by the brain
- numerical relativity: solving GR-sensitive problems with numerical methods
- NumPy: Python library for numerical programming with arrays
- pipeline: set series of tasks to perform on something
- quantum Monte Carlo: MC approach to difficult quantum mechanical problems
- random forest: algorithmic method of developing decision trees
- random walk: movement with random turns
- Riemann problem: consequence of discontinuities in numerical methods
- Runge-Kutta method: type of numerical method for integration and differential equations
- shearing box: method of simulating 3D MHD in disks
- smoothed-particle hydrodynamics: computational method for simulating fluid flows
- spectral method: method of numerically solving differential equations
- stencil: pattern of input to numerical solutions at a point
- symbolic regression: automated model-building by tinkering with formulae
- task-based parallelism: breaking a computation into tasks that can be run in parallel
- timestream: stream of digital data representing measurements taken over time
- umbrella sampling: method usable in MCMC that avoids some problems
- WKB method: method of numerically solving certain differential equations
computational astrophysics: astrophysical study through computer modeling
- HARM²: technique for parallelizing computations of radiation with hydrodynamics
computational fluid dynamics

lattice Boltzmann method: computational fluid dynamics method treating the fluid as particles

Computational Infrastructure for Geodynamics (CIG): initiative to produce Earth-science software
computational physics

computational astrophysics: astrophysical study through computer modeling

computations (numerical methods): using equations through repetitive arithmetic
computed tomography imaging spectrometer (CTIS): imaging spectrometer using CT algorithm to sort out overlapping orders
computer

Fugaku: Japanese petaflop/exaflop supercomputer
Odyssey: research supercomputer at Harvard sometimes used for astrophysics simulations
Stampede: research supercomputer at U. Texas

computerized tomography scan

tomography: observation of sections of a 3D object

computing

data cube: three-dimensional array of numerical data
deep learning: description of machine learning using substantial neural networks
exascale computing: exaFLOP computing capability, i.e., quintillion FLOPs
GPU: type of CPU tailored to handling computer graphics
Python: programming language used for a lot of astrophysics research

concept

AtLAST: concept for submillimeter survey telescope in Chile
Burst and All Sky Imaging Survey: late 1990s GRB-observer satellite proposal
California Extremely Large Telescope: concept for an extremely large telescope
Colossus Telescope: concept for a 50-meter telescope using interferometry
Cosmic Dawn Intensity Mapper: NASA concept for space telescope for intensity mapping
Enceladus Orbilander: concept for a NASA mission to Enceladus
Europa Lander: plan for a late 2020s Europa probe landing on the surface
GaiaNIR: concept for a Gaia follow-on including NIR astrometry
Giant Segmented Mirror Telescope: concept for an extremely large telescope
Large Submillimeter Telescope: concept for a 50-meter submillimeter telescope in Chile
PRIMA: concept for 2030s NASA 1.8-m FIR space telescope
solar powered satellite: concept for a satellite to collect and transfer energy to Earth
starshade: spacecraft to block light from a specific body
TAMBO: concept for neutrino detector in valley in Peru
THESEUS: plan for X-ray/Gamma-ray transient space mission
Uranus Orbiter and Probe: concept for mission to Uranus

Concept 1: see Origins Space Telescope
Concept 2: see Origins Space Telescope
CONCERTO: spectrometer aimed at mapping the [CII] line
concordance model: see alternative cosmologies
Concordia Station

Infrared Telescope Maffei: 80 cm infrared telescope in Antarctica

condensation: see refractory material
condensation: see volatile material
condensation temperature: see refractory material
condensation temperature: see volatile material
conditional luminosity function: function characterizing luminosity of galaxies with a given halo mass
conditional mass function (conditional stellar mass function): function characterizing galaxies within a halo of a given mass
conditional stellar mass function: function characterizing galaxies within a halo of a given mass
conductance: see siemens
conduction

stellar structure: the presumed internal structure of stars
white dwarf: stellar remnant largely of electron degenerate matter

conductive hydrogen (metallic hydrogen): a high-pressure state of hydrogen that is conductive
- metal: in astrophysics, any element more massive than helium
conductivity: see siemens
confidence interval: see error bar
configuration

monolithic mirror: telescope mirror made of one piece of material
segmented mirror: a telescope mirror formed of an array of smaller mirrors

confirmation bias: see selection bias
- blind analysis: performing experimental analysis without knowing the data
conformal field theory: a type of quantum field theory
- anti-de Sitter space: type of curved space
conformal mapping: see conformal field theory
conformal transformation: see conformal field theory
confusion: see confusion limit
confusion limit: limit on telescope imaging due to too many sources in the same region
confusion-limited image: see confusion limit
conic section: orbit shapes, like the intersection of a plane and cone
conjunction: see heliocentric system
- celestial event: something astronomical occurring visibly in the sky
CONSERT: see Rosetta
conservation law: property that remains unchanged by physical phenomena
Consiglio Nazionale delle Ricerche: Italian national research organization.
consortium

Astronet: European astronomy consortium
European Pulsar Timing Array: European collaboration of radio telescopes
International Pulsar Timing Array: organization of pulsar timing arrays
MicroFUN: observers following up on microlensing events in the galactic bulge
NANOGrav: effort to detect gravitational waves through pulsar timing
pulsar timing array: cooperating set of pulsar timing observatories
SuperWASP: broad Earth-based search for transiting planets
WASP: multi-university initiative to locate transiting planets

constant

Avogadro's number: number of hydrogen atoms per gram
Boltzmann constant: relates particle energy and temperature
Chandrasekhar limit: maximum mass of a white dwarf
gravitational constant: indicates how much pull between two masses
GZK limit: limit on energy of cosmic rays
Hubble constant: current rate of expansion of the universe
Hubble time: approximation of the age of the universe
Oort constants: two constants characterizing local Milky-Way motion
Planck constant: quantum of action in quantum mechanics
Rydberg constant: constant used in calculating atomic Hydrogen lines
Schönberg-Chandrasekhar limit: maximum stellar isothermal helium core mass
solar constant: flux from the Sun at 1 AU
Stefan-Boltzmann constant: relates radiation power to temperature and surface area
Tolman-Oppenheimer-Volkoff limit: maximum mass of a neutron star

constellation: division of the celestial sphere
- asterism: easily recognizable star pattern
- Orion: well-known constellation in the northern hemisphere
constitutive equations: see equation of state
constitutive relations: see equation of state
construction

4MOST: spectrograph in development for VISTA telescope
Africa Millimetre Telescope: planned 15 m radio telescope array in Namibia
Artemis program: NASA's program in development to send people to the moon
ASTHROS: balloon-borne 2.5-m submillimeter telescope
BINGO: future radio telescope for mapping distant neutral hydrogen
BlackGEM: telescope array to follow up gravitational wave signals
Cherenkov Telescope Array: ground gamma-ray telescope array in development
CONCERTO: spectrometer aimed at mapping the [CII] line
Dark Energy Spectroscopic Instrument: new instrument for measuring red-shift of distant objects
Deep Underground Neutrino Experiment: neutrino experiment under construction
European Extremely Large Telescope: 39-meter telescope under construction
Fred Young Submillimeter Telescope: 6-meter submillimeter survey telescope under construction in Chile
Giant Magellan Telescope: 24.5 meter telescope under construction
GUSTO: balloon-borne 0.9-m far-infrared telescope
HIRAX: radio telescope array for 21-cm surveying
Keck Planet Finder: Keck I spectrograph for RV measurements
KM3NeT: neutrino detector under construction in the Mediterranean Sea
MRO Interferometer: optical interferometer in New Mexico
Multi-object Optical and Near-IR Spectrograph: advanced spectrograph under development for VLT
Next Generation Very Large Array: planned radio telescope array as a follow-on to ALMA and the Jansky VLA
Northern Extended Millimeter Array: large radio telescope array under construction in Europe
OSAM-1: prototype space robot for servicing satellites
PLATO: planned observatory-satellite aimed at finding exoplanets
Project 8: experiment in development to measure neutrino mass
Psyche: space mission on its way to asteroid Psyche
PUNCH: 4 microsatellites to observe the Sun
Roman Space Telescope: proposed near-infrared space observatory
Rosalind Franklin: Mars rover in development for 2028 launch
Rubin Observatory: 8-meter survey reflector telescope under construction in Chile
Simons Observatory: CMB observatory on Atacama Desert
SPHEREx: all-sky spectral survey space-mission plan
Square Kilometre Array: planned radio telescope with square-kilometer collecting area
STUDIO: balloon-borne 0.5 m ultraviolet telescope
Subaru PFS: multi-object spectrograph in development for the Subaru telescope
Terra Hunting Experiment: search for exoplanets using HARPS3
Thirty Meter Telescope: extremely large telescope planned for Hawaii
Tiangong space station: Chinese manned space laboratory under construction in space
TolTEC: sensitive infrared camera under construction for the LMT
Tomographic Ionized-carbon Mapping Experiment: instrument in development to map the [CII] line
University of Tokyo Atacama Observatory: observatory for a 6.5 m infrared telescope under construction
UVSC Pathfinder: instrument to observe the Sun
WEAVE: multi-object spectrograph on the WHT

constructive interference

interference: result of interaction of waves

contact binary: binary stars orbiting so close they are touching
contact binary: see binary star
- black hole merger: two black holes meeting and forming one
contamination: see completeness
continuous absorption: the absorption of a whole section of a spectrum
continuous Galerkin method

discontinuous Galerkin method: computational method for PDEs handling discontinuities

continuous gravitational wave: long-lasting repeating GWs such as from orbits
continuous random variable: see probability density function
- probability mass function: shows probability of taking one of a number of discrete values
continuous shock: see shock wave
continuous spectrum: smooth spectrum or portion of spectrum with no lines
continuous viewing zone: region of sky that can be viewed 7×24×365
continuous-wave frequency-modulated: see frequency modulation
continuum: portion of a continuous spectrum not affected by a spectral feature
continuum (continuous spectrum): smooth spectrum or portion of spectrum with no lines
- continuous absorption: the absorption of a whole section of a spectrum
- continuum emission: continuous spectrum such as black-body radiation or bremsstrahlung
continuum emission: continuous spectrum such as black-body radiation or bremsstrahlung
CONTOUR: failed 2002 NASA astroid flyby mission
convection: a heated fluid's flow due to its low density and buoyancy
- convection zone: region of a star transmitting energy through convection
- dredge-up: stellar convection bringing up fused material
- mixing length theory: tractable simplified model of convection
- Rayleigh number: measure reflecting a fluid system's propensity to convection
- RT instability: result of lighter fluid pushing a heavier fluid
- stellar structure: the presumed internal structure of stars
convection zone: region of a star transmitting energy through convection
- stellar structure: the presumed internal structure of stars
convective envelope (convection zone): region of a star transmitting energy through convection
convective mantle

dynamo: mechanism for generating magnetic fields around astronomical bodies

convective overshoot: see convection
convective parameterization: see subgrid-scale physics
convective region (convection zone): region of a star transmitting energy through convection
convective Rossby number: see Rossby number
convective Urca process: see Urca process
convective zone (convection zone): region of a star transmitting energy through convection
convergent point: see moving-cluster method
convergent point method: see moving-cluster method
convolution: type of product function of two functions
- mixture: type of probability distribution resulting from two others
convolutional neural network: type of image processing software
- U-Net: neural network software for image reconstruction
COO: see double star designation
cool carbon star: see carbon star
Cool Companions on Ultrawide Orbits (COCONUTS): survey to image companions of stars
cool galactic carbon star: see carbon star
cooling flow: inward flow of ICM within galaxy clusters
- Zwicky 3146: nearby large galaxy cluster
cooling flow problem: see cooling flow
cooling function: function relating a gas's cooling rate to its temperature
cooling timescale: see timescale
- giant planet: planet of more than 10 Earth masses
Cooper pair: pair of electrons sharing a particular type of bond
coordinate

declination: direction coordinate above/below celestial equator
epoch: when an object was at a particular set of celestial coordinates
meridian: circle around the Earth passing through both poles
right ascension: direction coordinate along celestial equator
Terrestrial Time: current measure of time for astronomical observations on Earth

coordinate distance: see comoving units
coordinate system

ecliptic coordinate system: celestial coordinate system system based upon Earth's orbital plane
equatorial coordinate system: latitude/longitude-like system for the celestial sphere
galactic coordinate system: celestial coordinate system system based upon the galactic plane
horizontal coordinate system: celestial coordinate system based upon horizon and north
International Celestial Reference System: standardized variation of equatorial coordinate system
Radio Optical Reference Frame: 1994 celestial reference frame based on 436 sources
supergalactic coordinate system: celestial coordinate system system based upon the supergalactic plane

Coordinated Molecular Probe Line Extinction Thermal Emission Survey (COMPLETE Survey): survey of star forming regions
coordinated universal time

time standard: method of designating points in time and quantifying time periods

coordinates

celestial coordinate system: system for specifying position of celestial objects
celestial equator: equator-like line around the celestial sphere
celestial pole: point within the celestial sphere aligned with Earth's rotation axis
celestial sphere: the sky in considered as a sphere surrounding the observer
ecliptic: path of the Sun on the celestial sphere as seen from Earth
equinox: point-in-time when tilt of Earth is neither toward nor away from the Sun
galactic north: determination of the more northern direction of the Milky Way's axis
galactic plane: plane in which the stars of the Milky Way reside
local sidereal time: same as angular hours right ascension of the zenith
phone number: colloquial expression for coordinates
plane of the sky: plane tangent to the celestial sphere
solar time: time based upon the position of the Sun in the Earth's sky
torus coordinates: coordinates for toruses

Coordinates, Sizes, Magnitudes, Orientation, and Shapes: see SuperCOSMOS Sky Survey
COP: see double star designation
Copernicus: see Orbiting Astronomical Observatory
Copernicus Complexio: high-resolution cosmological N-body simulation
Copernicus Complexio Low Resolution: see Copernicus Complexio
coplanar flip: see planetary migration
COPSS: survey of CO from star forming epoch
COR1: see STEREO
COR2: see STEREO
cor2

carbonate-silicate cycle: long-term cycle that sequesters Earth carbon

Cordóba Observatory: see Bonner Durchmusterung Catalog
Cordelia: see shepherd moon
Cordoba Durchmusterung: see Bonner Durchmusterung Catalog
core (dense core): dense molecular cloud
core (stellar core): the middle of a star
core: see core-cusp problem
- gas planet: planet made largely of gas
core accretion: see core accretion model
core accretion model: model for the formation of giant planets
core accretion model: see giant planet formation
- gravitational instability model: model for the formation of giant planets
core barrier: see planet formation
core collapse: results when the center of something loses its pressure
- globular cluster: spherical group of stars orbiting a galaxy
- Messier 15: globular cluster with collapsed core
core collapse progenitor: see core collapse supernova
core collapse supernova: supernova resulting from the collapse of the core of a star
- alpha-enhanced: metallicity with a high percentage of alpha elements
- core collapse: results when the center of something loses its pressure
- long gamma-ray burst: GRB lasting more than two seconds
- magnetorotational supernova: type of core collapse supernova
- pair-instability supernova: type of large supernova
- supernova: stellar explosion larger than a nova
- supernova progenitor: the star or star system that produces a supernova
core collapse supernova progenitor: see supernova progenitor
core flash: see helium flash
core mass function (dense core mass function): function describing range of masses of dense cores
core-cusp problem: theories and observation show different dwarf galaxy rotation curves
core-driven escape: see atmospheric escape
core-mantle boundary: see cosmic microwave background
Coriolis effect: see Coriolis force
- Hadley cell: circulation pattern of up at the equator, poleward, down, and back
Coriolis force: apparent force in a rotating frame of reference
CorMASS: near-infrared spectrograph
Cornell Caltech Atacama Telescope (CCAT): 25-meter submillimeter telescope plan for Chile
Cornell Massachusetts Slit Spectrograph (CorMASS): near-infrared spectrograph
Cornell University

Carl Sagan Institute: group researching finding life on other planets and moons

corner.py: Python library for scatter plot matrices
corona: plasma surrounding a star
corona (AGN corona): plasma surrounding or near an AGN
- CLE: code to synthesize polarized emission lines of the solar corona
- coronagraph: telescope feature to block light from a specific body
- coronal hole: cool, low-density portions of the Sun's corona
- coronal loop: visible loop extending out of the Sun's surface and back
- coronal mass ejection: mass of plasma ejected from the Sun
- Coronal Solar Magnetism Observatory: proposed solar observatory
- COSIE: EUV spectrograph to analyze the corona
- flux rope: rope-shaped structure in magnetic fields associated with coronal mass ejections
- magnetic arcade: series of arch-like magnetic flux lines on the Sun
- magnetic dipole radiation: EMR naturally generated by a spinning magnetic dipole
- Parker wind: model of the solar wind
- solar flare: sudden brightening of the Sun
- solar wind: charged particles emanating from the Sun
- standard model of a flare: description of how solar flares function
- stellar atmosphere: photosphere and above
- Sun surface features: features on the Sun's surface
- TRACE: former solar observing satellite
- transition region: middle layer of the Sun's atmosphere
corona size: see AGN corona
coronagraph: telescope feature to block light from a specific body
- corona: plasma surrounding a star
- filter designator: indicators of a filter used in imaging
- solar telescope: telescope designed to observe the Sun
- UVSC Pathfinder: instrument to observe the Sun
coronagraphy: see coronagraph
coronal gas: see interstellar medium
coronal hole: cool, low-density portions of the Sun's corona
- Sun surface features: features on the Sun's surface
Coronal Line Emission Code (CLE): code to synthesize polarized emission lines of the solar corona
coronal loop: visible loop extending out of the Sun's surface and back
- magnetic arcade: series of arch-like magnetic flux lines on the Sun
- standard model of a flare: description of how solar flares function
- Sun surface features: features on the Sun's surface
coronal mass ejection: mass of plasma ejected from the Sun
- DISCOVR: space weather satellite
- ejection: forcing or throwing something out
- ESA Vigil: plan for space-weather warning satellite at L5
- flux rope: rope-shaped structure in magnetic fields associated with coronal mass ejections
- Forbush decrease: decrease in cosmic rays after a coronal mass ejection
- mass: object's quality that determines the effects of forces and gravity
- solar energetic particle: high-energy particles from the Sun
- solar eruption: sudden brightening of the Sun
- solar flare: sudden brightening of the Sun
- solar particle event: episode of higher velocity solar wind
- solar storm: general term for events on the Sun
- space weather: varying conditions in space affecting Earth and humans
- Sun surface features: features on the Sun's surface
- UVSC Pathfinder: instrument to observe the Sun
Coronal Solar Magnetism Observatory: proposed solar observatory
Coronal Spectrographic Imager in the EUV (COSIE): EUV spectrograph to analyze the corona
Coronal Spectropolarimeter for Airborne Infrared Research: see ASPIRE
COROT: observatory-satellite to look for transiting exoplanets and stellar oscillations
corotation resonance: orbit resonant with a nearby high-density portion of a disk
- Lindblad resonance: resonant orbits within a disk due to a high-density portion
corotation torque: a torque on a planet from co-orbiting planetary disk material
- corotation resonance: orbit resonant with a nearby high-density portion of a disk
corrected AIC: see Akaike information criterion
correction: see gravity anomaly
correction factor: see correction term
correction term: term added to a formula to mitigate an imperfection
Corrective Optics Space Telescope Axial Replacement: see Hubble Space Telescope
correlated: values of two functions having the same sign
correlation function

N-point function: general term for analyses-techniques of spatial data

correlator: unit that interferes wave signals for interferometry
CORSA-b

Japan Aerospace Exploration Agency: Japan agency includes astronomical research

CORSAIR: see ASPIRE
Corvus

Sloan Great Wall: large slab of galaxies discovered in SDSS

COS: see Hubble Space Telescope
COS: see rare designator prefixes
Cos-B: 1970s satellite for studying gamma rays
COSAC: see Rosetta
COSI: 2000s balloon-based gamma ray telescope
COSIE: EUV spectrograph to analyze the corona
COSIMA: see Rosetta
COSINE-100: dark matter detection experiment in South Korea
COSINE-200: see COSINE-100
COSMIC: see Hale Telescope
Cosmic Anisotropy Polarization Mapper (CAPMAP): early 2000s array that surveyed CMB polarization
Cosmic Anisotropy Telescope: 1990s interferometer to measure CMB variations
- Mullard Radio Astronomy Observatory: radio observatory near Cambridge, UK
Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey: early-universe survey by HST
Cosmic Background Explorer: 1989 satellite for surveying the CMB
Cosmic Background Imager: radio telescope in Chile observing the CMB
Cosmic Background Imager 2: see Cosmic Background Imager
cosmic background radiation: electromagnetic radiation coming from every direction
cosmic censorship hypothesis (law of cosmic censorship): a singularity cannot be observed
COSMIC DANCe (Dynamical Analysis of Nearby Clusters): survey of stars in stellar clusters
COSMIC DANCe: see Dynamical Analysis of Nearby Clusters
cosmic dawn: see dark age
Cosmic Dawn Intensity Mapper: NASA concept for space telescope for intensity mapping
cosmic distance

standard candle: astronomical object whose brightness can be determined
standard ruler: astronomical phenomenon whose size can be determined

cosmic distance ladder: sequence of methods of measuring distance to astronomical objects
- standard siren: transient whose gravitational waves indicate a specific distance
cosmic distance scale: see cosmic distance ladder
- standard candle: astronomical object whose brightness can be determined
- standard ruler: astronomical phenomenon whose size can be determined
cosmic dust: dust in space such as interstellar dust
Cosmic Dust Analyzer

Cassini: explorer spacecraft sent to Saturn

Cosmic Evolution Early Release Science (CEERS): JWST early release observation program covering the EGS
Cosmic Evolution Early Release Science: see James Webb Space Telescope
Cosmic Evolution Survey: investigation of dark matter and the universe's large scale structure
Cosmic Explorer: concept for a very large LIGO-like GW detector
Cosmic Explorer 1: see Cosmic Explorer
Cosmic Explorer 2: see Cosmic Explorer
cosmic gamma ray background: gamma-ray radiation seen everywhere
cosmic high noon (peak star-formation epoch): around 10 billion years ago when star formation peaked
Cosmic Hot Interstellar Plasma Spectrometer (CHIPS): small satellite to investigate ISM plasma
Cosmic Hot Interstellar Plasma Spectrometer Satellite (CHIPS): small satellite to investigate ISM plasma
cosmic inflation (inflation): theorized rapid expansion of the very early universe
cosmic infrared background: widespread infrared radiation not associated with known sources
- CIBER: sounding-rocket survey of near-infrared background
Cosmic Infrared Background Experiment (CIBER): sounding-rocket survey of near-infrared background
cosmic lens: see current sheet
Cosmic Lens All-sky Survey: 1990s/2000s radio survey aimed at gravitational lensing
cosmic light horizon (particle horizon): furthest point from which light can reach us
cosmic microwave background: microwave radiation coming from every direction
- initial fluctuations: early universe density variations leading to current universe
- microwave: electromagnetic radiation, frequency 300 MHz to 300 GHz
- sigma-8 tension: Lambda CDM anomaly regarding matter fluctuation
cosmic microwave background dipole: see CMB anisotropies
cosmic microwave background radiation (cosmic microwave background): microwave radiation coming from every direction
cosmic neutrino background: low-energy neutrinos left over from early universe
- cosmic background radiation: electromagnetic radiation coming from every direction
cosmic neutrinos (cosmic neutrino background): low-energy neutrinos left over from early universe
cosmic noon (peak star-formation epoch): around 10 billion years ago when star formation peaked
cosmic optical background: widespread optical radiation not associated with known sources
cosmic ray astronomy: see cosmic rays
cosmic ray background: see cosmic rays
cosmic ray spallation: see nucleosynthesis
- lithium: metal, Li, atomic number 3
cosmic rays: very-high-energy particles from beyond the solar system
- Advanced Composition Explorer: satellite collecting solar wind and cosmic rays
- air shower: particles and EMR generated in the atmosphere by incoming particle or EMR
- ARGO-YBJ Experiment: cosmic-ray/gamma-ray detector in Tibet
- CASA-MIA: 1990s cosmic-ray detector in Utah
- EUSO-SPB: balloon-borne cosmic ray observatory
- Fly's Eye: 1980s cosmic-ray observatory
- Forbush decrease: decrease in cosmic rays after a coronal mass ejection
- GRAPES-3: Cherenkov telescope at Ooty, India
- GZK limit: limit on energy of cosmic rays
- High Resolution Fly's Eye: 1990s-2000s cosmic-ray observatory
- INTEGRAL: European gamma ray observatory-satellite
- International Cosmic Ray Conference: bi-annual cosmic ray conference since 1947
- LHAASO: gamma ray/cosmic ray observatory in China
- localization: ability to identify location of a transient
- LOPES: cosmic ray detector that detected resulting radio
- Oh-My-God Particle: extremely energetic particle from space detected in 1991
- Orbiting Wide-angle Light Collectors: space mission concept to detect cosmic rays through Earth atmosphere light flashes
- PAMELA: cosmic ray detector attached to satellite
- Pierre Auger Observatory: cosmic-ray observatory in Argentina
- POEMMA: planned space cosmic-ray neutrino observatory
- Swordy plot: well-known diagram plotting cosmic ray flux to particle energy
- Telescope Array Project: cosmic-ray observatory aiming for extremely energetic particles
- Tunka experiment: Russian Cherenkov detector aimed at cosmic rays and gamma rays
cosmic ruler: see cosmic distance ladder
cosmic scale factor (scale factor): relative size of the universe as a function of time
cosmic string: rent in spacetime
- topological defect: defect in space that could arise in the early universe
cosmic time: time since the Big Bang
cosmic time dilation (cosmological time dilation): very distant events appear to take longer
cosmic variance: density variation on a cosmic scale
cosmic void (void): empty spaces between large scale structures
cosmic web: hypothesized structure of the dark matter throughout the universe
cosmic web (large scale structure): the universe's structure as in placement of clusters
- dark matter filament: hypothesized type of long, thin volume of dark matter
- structure formation: formation of dark matter halos, galaxy clusters, and galaxies
cosmic X-ray background: X-ray radiation coming from outside the Milky Way
cosmic X-ray background radiation (cosmic X-ray background): X-ray radiation coming from outside the Milky Way
Cosmic X-Ray Spectroscopy: see OSO 8
cosmic X-ray survey: see X-ray
cosmic year: see Milky Way
COSMO (Coronal Solar Magnetism Observatory): proposed solar observatory
COSMO11: see COSMOSOMAS
COSMO15: see COSMOSOMAS
cosmogenic neutrino: see GZK limit
cosmogony: see cosmology
cosmological: see cosmology
cosmological band shifting (band shifting): effect of redshift on photometry
cosmological constant: force counteracting the universe's inward gravitational pull
- Big Bang: theoretical event when the universe expanded from a point
cosmological distance: appreciable distance across the universe
- cosmology: study of the life of the universe
cosmological distance ladder (cosmic distance ladder): sequence of methods of measuring distance to astronomical objects
cosmological EOS (cosmological equation of state): equation of state of dark matter
- dark energy: energy theorized to accelerate the expansion of the universe
cosmological EOS parameter: see cosmological equation of state
- dark energy: energy theorized to accelerate the expansion of the universe
cosmological equation of state: equation of state of dark matter
cosmological equation of state: see wCDM
- dark energy: energy theorized to accelerate the expansion of the universe
cosmological equation of state parameter: see cosmological equation of state
- dark energy: energy theorized to accelerate the expansion of the universe
cosmological expansion (Hubble expansion): ongoing expansion of the universe
cosmological horizon (particle horizon): furthest point from which light can reach us
cosmological inflation (inflation): theorized rapid expansion of the very early universe
cosmological lithium problem: see lithium
cosmological model: model of the workings and history of the universe
cosmological models

Alcock-Paczyński effect: type of distortion of the apparent depth of galaxy clusters

cosmological principle: on a large scale the universe is the same everywhere
cosmological redshift: redshift of distant objects due to the Hubble expansion
- Doppler shift: wave frequency difference due to relative velocity difference with source
- redshift: change to longer wavelengths due to Doppler effects
- tired light: an alternate theory explaining the cosmological redshift
cosmological simulation: simulation of the history of the universe
- computational astrophysics: astrophysical study through computer modeling
- cosmological model: model of the workings and history of the universe
cosmological simulations

cosmic web: hypothesized structure of the dark matter throughout the universe
dark matter filament: hypothesized type of long, thin volume of dark matter

Cosmological Structures On Medium Angular Scales (COSMOSOMAS): 1990s-2000s microwave survey
cosmological time dilation: very distant events appear to take longer
- time dilation: relativity's ability to make time differ for different objects
cosmological zoom simulation: cosmological simulation plus higher resolution simulations of selected space
cosmologist: see cosmology
cosmology: study of the life of the universe
- 21-cm experiment: search for redshifted 21-cm hydrogen emission lines
- Alcock-Paczyński effect: type of distortion of the apparent depth of galaxy clusters
- alternative cosmologies: cosmological models other than Big Bang/Lambda-CDM
- angular power spectrum: method of characterizing the CMB
- anisotropy: directional-dependence such as temperature variation around the CMB
- Astrid simulation: cosmological simulation over z = 99 to 3
- atomic dark matter: theory of particle dark matter in which they interact
- baryon acoustic oscillations: density fluctuations stemming from acoustic waves in the early universe
- Baryon Oscillation Spectroscopic Survey: survey of spatial distribution of luminous red galaxies and quasars
- BICEP2: survey to measure the polarization of the CMB
- Big Bang: theoretical event when the universe expanded from a point
- Big Bang nucleosynthesis: creation of atomic nuclei in the very early universe
- Big Crunch: theoretical end of universe drawn together by gravity
- BigBOSS: BOSS survey follow-on
- Bolshoi simulation: cosmological simulation
- BOOMERanG: 1990s-2000s balloon-borne 1.3-meter millimeter telescope
- brane: mathematical object with dimensions
- Butcher-Oemler effect: observation of more blue galaxies at z > 0.3
- Calán/Tololo Supernova Survey: late 1980s to early 1990s search to redshift 0.1
- Carnegie Supernova Project: survey of supernovae lightcurves
- ChaNGa: cosmological-simulation project active since circa 2015
- chemical equilibrium: state where chemical makeup is unchanging
- CMB anisotropies: variations in the spectrum of the CMB
- CMB dipole: CMB variation due to our velocity
- CMB polarization: effects of scattering and lensing on the CMB
- CMBFAST: software to calculate CMB anisotropies
- cold dark matter: one of three classes of "particle dark matter" theory
- comoving units: units of measure that incorporate the scale factor
- Copernicus Complexio: high-resolution cosmological N-body simulation
- core-cusp problem: theories and observation show different dwarf galaxy rotation curves
- Cosmic Assembly Near-infrared Deep Extragalactic Legacy Survey: early-universe survey by HST
- Cosmic Evolution Survey: investigation of dark matter and the universe's large scale structure
- cosmic time: time since the Big Bang
- cosmic variance: density variation on a cosmic scale
- cosmological constant: force counteracting the universe's inward gravitational pull
- cosmological distance: appreciable distance across the universe
- cosmological equation of state: equation of state of dark matter
- cosmological model: model of the workings and history of the universe
- cosmological principle: on a large scale the universe is the same everywhere
- cosmological redshift: redshift of distant objects due to the Hubble expansion
- cosmological simulation: simulation of the history of the universe
- cosmological time dilation: very distant events appear to take longer
- cosmological zoom simulation: cosmological simulation plus higher resolution simulations of selected space
- cosmos: alternate word for universe
- critical density: density of the universe which leaves it flat
- curvature: unflatness of space
- D56: a target survey field of ACT telescope
- damped Lyman alpha absorber: object producing broadened lines in a Lyman alpha forest
- dark age: interval when the universe's hydrogen atoms were neutral
- dark energy: energy theorized to accelerate the expansion of the universe
- Dark Energy Spectroscopic Instrument: new instrument for measuring red-shift of distant objects
- dark flow: non-random patterns in peculiar velocity of galaxy clusters
- deceleration parameter: measure of the Hubble expansion's deceleration
- decoupling: some type of particle stops being destroyed as often as it is created
- Deep Lens Survey: investigating mass distribution of the universe
- density parameter: ratio of a density with the critical density
- diffusion damping: a damping process within the plasma during recombination
- dwarf galaxy problem: theories have more dwarf galaxies than are observed
- EAGLE: simulation of galaxy formation and evolution
- early universe: from the Big Bang to recombination
- EBEX: balloon-based CMB polarization survey
- Einstein-de Sitter model: universe tuned to the smallest expansion that continues forever
- Enzo: hydrodynamic simulation system
- epoch of reionization: time when the universe's neutral hydrogen atoms ionized
- escape fraction: fraction of ionizing photons escaping a body
- ESSENCE: survey using supernova data to study dark energy
- false vacuum: apparent QFT vacuum
- FIRE Simulations: high resolution simulation of galaxies
- foreground subtraction: removing unwanted sources of EMR in intensity mapping
- free streaming: particles moving long distances without disturbance
- freeze-out: particles existing long-term after a decoupling
- Friedmann model: type of model of universe incorporating general relativity
- fuzzy dark matter: concept of extremely light dark matter particles
- GADGET-2: an n-body/SPH simulation computer program
- galaxy bias: degree to which galaxy density fails to correspond to dark matter density
- galaxy filament: thread-like formations of galaxies, 50 to 80 megaparsecs
- galaxy power spectrum: a power spectrum describing the occurrence of galaxies in space
- GALFORM: semi-analytic galaxy formation model
- Giant Gemini GMOS survey: spectrographic survey of distant quasars
- Gunn-Peterson trough: spectral feature in EMR from redshift 6+
- halo mass function: mass of distribution of dark matter
- halo model: model of dark matter density presuming it resides in halos
- hierarchical assembly of galaxies: development of large galaxies by combining small ones
- Hubble constant: current rate of expansion of the universe
- Hubble diagram: diagram comparing redshift with distance
- Hubble expansion: ongoing expansion of the universe
- Hubble tension: inconsistency in recent determinations of the Hubble constant
- Illustris Project: 2013-2015 series of cosmological simulations
- inflation: theorized rapid expansion of the very early universe
- initial fluctuation spectrum: the power spectral density of the early universe
- initial fluctuations: early universe density variations leading to current universe
- intensity mapping: measure of cosmic matter density
- intergalactic dust: dust not within galaxies
- isotropy: uniformity in all directions
- Kapteyn universe: early 20th century model of the universe centered on the Milky Way
- Lambda-CDM model: Big-Bang cosmological model with a cosmological constant and cold dark matter
- large scale structure: the universe's structure as in placement of clusters
- LasDamas: simulations of large scale evolution of dark matter and galaxies
- Lick Observatory Supernova Search: search for supernovae for cosmological study
- LiteBIRD: planned spacecraft to map CMB polarization
- LSPE-SWIPE: plan for a balloon-based CMB polarization survey
- luminosity distance: distance to an object based upon the distance's effect on received flux
- missing baryon problem: standard theory suggests more baryonic matter than observed
- Multi-Epoch Nearby Cluster Survey: Type Ia supernova survey in clusters at z = 0.1
- N-point function: general term for analyses-techniques of spatial data
- NOAO Deep Wide-field Survey: survey investigating large scale structure of the universe
- observable universe: that part of the universe that we can conceivably observe
- Olbers' paradox: argument using the dark of the sky regarding the nature of the universe
- Pantheon: catalog of well-checked Type Ia supernovae
- particle horizon: furthest point from which light can reach us
- particle physics: physics such as carried out in accelerators
- peak star-formation epoch: around 10 billion years ago when star formation peaked
- pion: first type of meson discovered
- Press-Schechter formalism: cosmological model of how structures form from fluctuations
- primordial black hole: black holes forming at the most dense volumes when inflation ceased
- primordial gravitational waves: gravitational waves formed in the early universe
- PROMETHEUS/VERTEX: hydrodynamic simulation system
- protogalaxy: gas cloud forming a galaxy
- QUaD: survey to measure the polarization of the CMB
- quark-gluon plasma: extreme-temperature state of matter
- QUBIC: survey measuring the polarization of the CMB
- QUIET: survey to measure the polarization of the CMB
- radiation era: early-universe era when radiation pressure dominated
- radio source counts: using radio source population characteristics to determine curvature
- RAMSES: hydrodynamic simulation system
- Randall-Sundrum model: particular 5-dimensional cosmological model
- REBELS: survey of star-forming galaxies during the reionization
- recombination: time when the universe's ionized hydrogen atoms neutralized
- redshift survey: survey of the universe aiming at three dimensions
- redshift-angular size relation: how observed size of an object depends on its redshift
- redshift-magnitude relation: how apparent magnitude depends on redshift
- reheating: theorized increase in temperature after cosmological inflation
- relic: particles left over from the events of the early universe
- repulsive dark matter: concept of dark matter that resists extreme dark-matter density
- RHAPSODY: simulation of galaxy cluster dark-matter halos
- Romulus simulations: cosmological-simulation project active since circa 2015
- Sachs-Wolfe effect: gravitational redshift of the CMB
- satellite plane problem: satellite galaxies inexplicably tend to fall in a plane
- scale factor: relative size of the universe as a function of time
- Scott effect: bias toward finding clusters that have bright galaxies
- sigma-8 tension: Lambda CDM anomaly regarding matter fluctuation
- SIMBA: galaxy formation simulation code
- spacetime diagram: graph of simplified spacetime, with fewer space dimensions
- structure formation: formation of dark matter halos, galaxy clusters, and galaxies
- sub-GeV dark matter: a more-massive type of CDM
- Sunyaev-Zel'dovich effect: type of distortion of the CMB
- Supernova Cosmology Project: used supernova data to determine a history of the universe's expansion
- Supernova Legacy Survey: detect and monitor supernovae to measure the effects of dark energy
- surface of last scattering: sphere around us from which CMB photons are just reaching us
- symmetry breaking: loss of symmetry, such as due to loss of stability in a regime change
- Tenerife Experiment: 1980s-1990s survey of CMB anisotropies
- Theory of Everything: single law explaining the four forces of nature
- time-delay cosmology: working out space geometry from delays due to gravitational lensing
- tired light: an alternate theory explaining the cosmological redshift
- topological defect: defect in space that could arise in the early universe
- VIMOS-VLT Deep Survey: spectroscopic survey of 100,000 high-redshift galaxies
- void: empty spaces between large scale structures
- wCDM: Big-Bang cosmological model with constant cosmological equation of state
- Wide-field Multi-object Spectrograph: proposed instrument to detect baryon acoustic oscillations
- Wilkinson Microwave Anisotropy Probe: spacecraft that measured variations in the cosmic background radiation
- Zel'dovich approximation: model of the formation of cosmological structure
Cosmology Large Angular Scale Surveyor: see Cosmic Lens All-sky Survey
cosmology simulation (cosmological simulation): simulation of the history of the universe
COSMOS (Cosmic Evolution Survey): investigation of dark matter and the universe's large scale structure
COSMOS: see SuperCOSMOS Sky Survey
COSMOS: see Víctor M. Blanco Telescope
- DEVILS: visible-light spectrographic survey of 56k distant galaxies
- FourStar Galaxy Evolution Survey: infrared deep-survey to detect galaxies
- MIGHTEE: radio survey of four established deep fields
cosmos: alternate word for universe
cosmos: see cosmology
COSMOS AzTEC-3 (AzTEC-3): very distant starburst galaxy
COSMOS Field: see Cosmic Evolution Survey
COSMOSOMAS: 1990s-2000s microwave survey
COSPAR (Committee on Space Research): international collaboration established by International Council for Science
COSPIN: see Ulysses
COSTAR: see Hubble Space Telescope
COSTEP: see Solar and Heliospheric Observatory
COU: see double star designation
coudé focus: see coudé focus telescope
coudé focus telescope: type of Nasmyth telescope with additional mirrors
Couder telescope

Schwarzschild telescope: type of two-mirror reflector telescope

coulomb

tesla: unit of magnetic flux density

Coulomb force: see Coulomb's law
- Vlasov-Poisson equation: equation describing plasma ignoring the magnetic field
Coulomb scattering

stellar encounter: stars passing close to each other

Coulomb's constant: see Coulomb's law
Coulomb's law: static electrical force relation
- electric field: electric force as distributed over a space
Council of German Observatories: German astronomy research council
Council of Giants: twelve large galaxies surrounding the Local Group
counterpart: image found at same coordinates using different EMR
COUP: survey of X-ray sources in the Orion Nebula
Coupled Ion-Neutral Dynamics Investigation: space weather investigation instruments on USAF spacecraft
coupling constant: see quantum field theory
COUPP: see PICO experiment
Courant condition: see finite difference method
Courant-Friedrichs-Lewy-condition: see finite difference method
covalent bond

adsorption: adhesion to a surface
oxidation state: number of electrons loaned out by an atom in an ionic bond

cow: see AT2018cow
Cox: see rare designator prefixes
CP: see Bonner Durchmusterung Catalog
CP: see millisecond pulsar
CP: see rare designator prefixes
CP 1919

pulsar: type of astronomical body with EMR in regular cycles of seconds or less

CP star (chemically peculiar star): star with SED showing presence metals unusual for stars
CP symmetry

axion: proposed light, electrically neutral elementary particle

CP1: see chemically peculiar star
CP2: see chemically peculiar star
CP3: see chemically peculiar star
CP4: see chemically peculiar star
CPAPIR

SIMP: 2000s infrared proper-motion survey

CPC: see IRAS
CPD: see Bonner Durchmusterung Catalog
CPM: see AstroSat
CPM: see rare designator prefixes
CPO: see double star designation
CPO: see rare designator prefixes
CPR (circular polarization ratio): ratio of circular polarization handedness in reflected radar signal
CPS (Centre for the Protection of the Dark and Quiet Sky from Satellite Constellation Interference): IAU initiative to address the issue of satellite constellations
CPS: see SELENE
CPTA (Chinese Pulsar Timing Array): group of pulsars timed by FAST
CR (cosmic rays): very-high-energy particles from beyond the solar system
Cr (Collinder Catalog): 1930s catalog of 471 open clusters
Crab Nebula: supernova remnant in Taurus
- electron capture supernova: supernova from collapse of iron-free stellar cores
Crab Pulsar: see Crab Nebula
crab-type remnant: see supernova remnant
- Crab Nebula: supernova remnant in Taurus
CRAF (Comet Rendezvous Asteroid Flyby): 1980s/1990s NASA comet exploration plan
CRAFT: see Australian Square Kilometre Array Pathfinder
CRaTER: see Lunar Reconnaissance Orbiter
Crater II

Milky Way subgroup: the Milky Way and its satellites

CRATES: catalog of 8.4 GHz data on radio sources
CRB: see cosmic rays
CRBR: see rare designator prefixes
CRES (cyclotron radiation emission spectroscopy): method of measuring the KE of beta particles
CRES: see Project 8
CRESST (Cryogenic Rare Event Search with Superconducting Thermometers): a search for a candidate dark matter particle
CRESST-I: see Cryogenic Rare Event Search with Superconducting Thermometers
CRESST-II: see Cryogenic Rare Event Search with Superconducting Thermometers
CRESST-III: see Cryogenic Rare Event Search with Superconducting Thermometers
CRIRES: high resolution IR echelle spectrometer
CRIRES: see European Southern Observatory Very Large Telescope
CRIRES+: see CRIRES
CRIRES+: see European Southern Observatory Very Large Telescope
CRIS: see Advanced Composition Explorer
CRISM: see Mars Reconnaissance Orbiter
critical density: density of the universe which leaves it flat
- Big Crunch: theoretical end of universe drawn together by gravity
critical density of the universe (critical density): density of the universe which leaves it flat
critical point: see supercritical fluid
critical radius: see circumbinary planet
critical rotation: see stellar rotation
critical velocity: see stellar rotation
CRL: see AFGL Four Color Infrared Sky Survey
cross dispersion spectrograph: echelle spectrograph with additional disperser crosswise to the first
cross Dragone telescope: see Dragone telescope
cross section: "area" representation of probability of an interaction of particles
cross-staff: historical device for measuring angular distances
crossed-Dragone design: see Dragone telescope
crowd-sourcing: carrying out large efforts by combining that of many volunteers
crowdsource

Disk Detective: Zooniverse effort to find planets within protoplanetary disks
Galaxy Zoo: crowdsourcing website to identify galaxy types from surveys
Galaxy Zoo 2: crowd-sourced classification of hundreds of thousands of galaxies
Hubble Asteroid Hunter: Zooniverse effort to find asteroids in HST images
Planet Hunters: crowdsourcing website to identify galaxy types from surveys
Zooniverse: effort supporting research through crowdsourcing

CRRES (Combined Release and Radiation Effects Satellite): 1990s satellite investigating Earth's magnetosphere
CRS: see Voyager
CRSS: see ROSAT
CRTS

Catalina Sky Survey: survey of near-Earth objects

crust

load density: measure of rigidity of the crust of a body

crustal magnetism: magnetic fields independent of a world's core magnetic field
crustal plates: sections of the Earth's crust that move
cryogenic: colder than 120 kelvins
- cryogenic spectroscopy: laboratory spectroscopy of materials cooled to cryogenic temperatures
Cryogenic Comet Nucleus Sample Return (Comet Nucleus Sample Return): concept study for comet mission
Cryogenic Dark Matter Search: a search for a candidate dark matter particle
Cryogenic Infrared Echelle Spectrometer (CRIRES): high resolution IR echelle spectrometer
Cryogenic Nucleus Sample Return (Comet Nucleus Sample Return): concept study for comet mission
Cryogenic Rare Event Search with Superconducting Thermometers: a search for a candidate dark matter particle
cryogenic spectroscopy: laboratory spectroscopy of materials cooled to cryogenic temperatures
Cryogenic Underground Observatory for Rare Events (CUORE): experiment to sense neutrinoless double beta decay
cryolava: see cryovolcano
cryovolcanism: see cryovolcano
cryovolcano: eruption of substances that are liquid or gas at cold temperatures
crystal ice

snow line: distance from protostar so cool that water condenses

crystal nucleation: see supercooling
crystal nucleus: see supercooling
crystalline ice: see ice
CS: see tracer
CS metric: see Chern-Simons gravity
- theoretical modified GR metric: metric devised to define modifications to GR
CS60: see Mauna Loa Solar Observatory
CSA: includes astronomical research
- James Webb Space Telescope: 6.5-meter infrared space telescope at L2
- MOST: 2000s observatory-satellite looking for stellar oscillations
- NEOSSat: small spacecraft tracking NEOs
CSBN (Committee for Small-Body Nomenclature): early 2000s IAU division since replaced by WG-SBN
CSDC: see NOIRLab
CSE (circumstellar envelope): shell-like cloud surrounding a star
- asymptotic giant branch: a second stage of helium burning in some stars
- planetary nebula: glowing gas shell ejected by a red giant
CSHELL: see IRTF
CSI (Carl Sagan Institute): group researching finding life on other planets and moons
CSI (Catalog of Stellar Identification): a compilation of the catalogs, BD, CD, and CPD
CSI (Catalog of Stellar Identifications): 1970s catalog cross referencing existing star catalogs
CSIRO

ATNF Pulsar Catalogue: online catalog of pulsars
Australia Telescope Compact Array: radio telescope in eastern Australia

CSL: see rare designator prefixes
CSM: see circumstellar envelope
- superluminous supernova: stellar explosion larger than a supernova
CSMF (conditional stellar mass function): function characterizing galaxies within a halo of a given mass
CSN: see stellar nucleus
CSO (Caltech Submillimeter Observatory): 10.4 meter submillimeter telescope previously in Hawaii
CSO: see rare designator prefixes
- Mauna Kea: Hawaiian mountain, the site of observatories
- Mauna Kea Observatories: observatories on Mauna Kea in Hawaii
CSO-JCMT interferometer: see Caltech Submillimeter Observatory
CSP (Carnegie Supernova Project): survey of supernovae lightcurves
CSPN: see planetary nebula
CSPNe

planetary nebula: glowing gas shell ejected by a red giant

CSS (Catalina Sky Survey): survey of near-Earth objects
CSS: see Hubble Space Telescope
CSS: see rare designator prefixes
CST: variable star type meaning it is currently thought non-variable
CSV: see New Catalogue of Suspected Variable Stars
CSWA (Committee on the Status of Women in Astronomy): AAS committee
CT scan

tomography: observation of sections of a 3D object

CTA (Cherenkov Telescope Array): ground gamma-ray telescope array in development
CTA: see rare designator prefixes
- Roque de los Muchachos Observatory: observatory at La Palma in the Canary Islands
CTAO (Cherenkov Telescope Array): ground gamma-ray telescope array in development
CTB: see rare designator prefixes
CTCV: see rare designator prefixes
CTD: see rare designator prefixes
CTIO (Cerro Tololo Inter-American Observatory): NOIRLab observatory in Chile with Blanco telescope
- Calán/Tololo Supernova Survey: late 1980s to early 1990s search to redshift 0.1
- CTIO Upper-Scorpius OB Association Survey: survey of low-mass stars and brown dwarfs
- Dark Energy Survey: survey aimed at mapping the universe's expansion
- DECaLS: survey imaging part of SDSS footprint with DECam
- Deep Lens Survey: investigating mass distribution of the universe
- Evryscope: automated array of telescopes to uncover transients
- Kitt Peak National Observatory: NOIRLab observatory in Arizona with Mayall telescope
- Multiwavelength Survey by Yale-Chile: optical/NIR survey of four deep fields
- National Optical Astronomy Observatory: previous name of US optical astronomy organization
- NOAO Deep Wide-field Survey: survey investigating large scale structure of the universe
- SOAR Telescope: 4.1 m reflector telescope in Chile
- USNO Twin Astrograph: USNO astrograph deployed in 1970
- Víctor M. Blanco Telescope: 4 meter reflector telescope in Chile
CTIO 1.5m

Cerro Tololo Inter-American Observatory: NOIRLab observatory in Chile with Blanco telescope
CTIO Upper-Scorpius OB Association Survey: survey of low-mass stars and brown dwarfs
SIMP: 2000s infrared proper-motion survey
The Survey for Ionization in Neutral Gas Galaxies: survey of HI in galaxies found through the H-alpha line

CTIO Schmidt Camera: see Cerro Tololo Inter-American Observatory
- CTIO Upper-Scorpius OB Association Survey: survey of low-mass stars and brown dwarfs
- The Survey for Ionization in Neutral Gas Galaxies: survey of HI in galaxies found through the H-alpha line
CTIO Upper-Scorpius OB Association Survey: survey of low-mass stars and brown dwarfs
CTIS: imaging spectrometer using CT algorithm to sort out overlapping orders
CTOI: see Transiting Exoplanet Survey Satellite
CTQ: see Calán/Tololo Supernova Survey
CTS: see Calán/Tololo Supernova Survey
CTSS: see rare designator prefixes
CTTS: see T-Tauri star
CTX: see Mars Reconnaissance Orbiter
CubeSat: type of small satellite built around a set of modular parts
- CubIXSS: solar spectrometer satellite concept
- CUTE: CubeSat ultraviolet space telescope
CubeSat Imaging X-ray Solar Spectrometer (CubIXSS): solar spectrometer satellite concept
cubewano: see Kuiper Belt
Cubic Kilometre Neutrino Telescope (KM3NeT): neutrino detector under construction in the Mediterranean Sea
CubIXSS: solar spectrometer satellite concept
- CubeSat: type of small satellite built around a set of modular parts
CUORE: experiment to sense neutrinoless double beta decay
Curiosity: see Mars Science Laboratory
- CSA: includes astronomical research
- Mars: well-explored planet in the solar system
- Mars 2020: Mars rover mission currently on Mars after 2021 landing
- MMRTG: power source for space probes
curl: see mathematical field
- Poisson's equation: relates one function's Laplacian to another function
- polarization modes: curl- and divergent-like components of CMB polarization patterns
- vortensity: ratio of vorticity to surface mass-density
- vortex: fluid region where the flow is spinning
current

siemens: SI unit of electrical conductance

current sheet: slender sheet within a magnetic field where current flows
Curtis-Shapley Debate (Great Debate): historical debate regarding the nature of galaxies
curvature: unflatness of space
- geodesic: equivalent to a straight line within curved space
curvature fluctuation amplitude: see Lambda-CDM model
curvature of field (field curvature): focusing to a curved surface rather than a plane
curvature radiation: synchrotron-like radiation when particles follow curved field lines
curvature scalar: see curvature
curvature sensor: see wavefront sensor
curve of growth: see line broadening
curved space: see curvature
- wormhole: connection between two regions in a curved space
cusp: see core-cusp problem
cuspy halo problem (core-cusp problem): theories and observation show different dwarf galaxy rotation curves
cut-off frequency: see thermal bremsstrahlung
CUTE: CubeSat ultraviolet space telescope
CV (cataclysmic variable star): star whose magnitude is much brighter on occasion
CVZ (continuous viewing zone): region of sky that can be viewed 7×24×365
CW: see rare designator prefixes
CWFM: see frequency modulation
CWI: see Hale Telescope
CWISE: see Wide-field Infrared Survey Explorer
CWISEP: see Wide-field Infrared Survey Explorer
CWS: see SUNRISE
CXB (cosmic X-ray background): X-ray radiation coming from outside the Milky Way
- cosmic background radiation: electromagnetic radiation coming from every direction
CXBR (cosmic X-ray background): X-ray radiation coming from outside the Milky Way
CXC: see Chandra X-ray Observatory
CXE: see HEAO-1
CXO (Chandra X-ray Observatory): space X-ray telescope
CXOGC: see Chandra X-ray Observatory
CXOM31: see Chandra X-ray Observatory
CXOU: see Chandra X-ray Observatory
CXOU+J232327.8+584842: see Cassiopeia A
CXRB (cosmic X-ray background): X-ray radiation coming from outside the Milky Way
cyanide: see hydrogen cyanide
Cybele

asteroid family: set of asteroids based on similar orbits

cycloalkane: see hydrocarbon
cyclotron: see cyclotron radiation
cyclotron frequency: see cyclotron radiation
cyclotron radiation: radiation emitted when charged particles are accelerated
- electron scattering: any process that changes the course of an electron
cyclotron radiation emission spectroscopy: method of measuring the KE of beta particles
cyclotron radiation emission spectroscopy: see Project 8
Cygnus A: early-discovered radio galaxy showing a quasar
Cygnus Loop: supernova remnant in Cygnus
Cygnus OB2-12

hypergiant: extremely bright stars

Cygnus Rift: see Cygnus-X
Cygnus X Star Forming Region: see Dickel-Wendker-Bieritz Catalog
Cygnus-X: well-studied massive SF region
cylindrical radio telescope: see cylindrical telescope
cylindrical telescope: telescope with cylindrical reflectors
CYRA: see Big Bear Solar Observatory
Cz (Czernik Catalog): list of open clusters
Czernik: see Czernik Catalog
Czernik Catalog: list of open clusters
Czernik Open Cluster Catalogue (Czernik Catalog): list of open clusters
CZTI: see AstroSat

Index