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Space and Solar Glossary / Terms / Dictionary

Space and Solar Definitions - C

c - The speed of light, 299,792 km per second.

C-band - A range of microwave radio frequencies in the neighborhood of 4 to 8 GHz.

Caltech - The California Institute of Technology.

Carrier - The main frequency of a radio signal generated by a transmitter prior to application of any modulation.

Carrington Longitude - A system of fixed longitudes rotating with the sun.

Cassegrain - Reflecting scheme in antennas and telescopes having a primary and a secondary reflecting surface to "fold" the EMF back to a focus near the primary reflector.

CCD - Charge Coupled Device, a solid-state imaging detector.

CCS - Computer Command subsystem on board a spacecraft, similar to CDS.

CCSDS - Consultative Committee for Space Data Systems, developer of standards for spacecraft uplink and downlink, including packets.

CDR - GCF central data recorder.

CDS - Command and Data Subsystem onboard a spacecraft.

CDSCC - DSN's Canberra Deep Space Communications Complex in Australia.

CDU - Command Detector Unit onboard a spacecraft.

Centimeter - 10-2 meter.

Centimeter Burst - A solar radio burst in the centimeter wavelength range.

Central Meridian Passage (Cmp) - The passage of an active region or other feature across the longitude meridian that passes through the apparent center of the solar disk.

Centrifugal force - The outward-tending apparent force of a body revolving around another body.

Centripetal acceleration - The inward acceleration of a body revolving around another body.

CGPM - General Conference of Weights and Measures, Sevres France. The abbreviation is from the French. CGPM is the source for the multiplier names (kilo-, mega-, giga-, etc.) listed in this document.

Channel - In telemetry, one particular measurement to which changing values may be assigned.

Chromospheres - The layer of the solar atmosphere above the photosphere and beneath the transition region and the corona.

Chromospheres Events - Some flares are just chromospheres events without centimetric bursts or ionospheric effects. (sid) (class c flare

CIT - California Institute of Technology, Caltech.

CMC - Complex Monitor and Control, a subsystem at DSCCs.

CMD - DSN Command System. Also, Command data.

CNES - Centre National d'Études Spatiales, France.

Coherent - Two-way communications mode wherein the spacecraft generates its downlink frequency based upon the frequency of the uplink it receives.

Coma - The cloud of diffuse material surrounding the nucleus of a comet.

Comets - Small bodies composed of ice and rock in various orbits about the sun.

Comprehensive Flare Index (Cfi) - The indicative of solar flare importance given by the sum of the following five components a) importance of ionizing radiation as indicated by time- associated short wave fade or sudden ionospheric disturbance; (scale 0-3) b) importance of h-alpha flare; (scale 0-3) c) magnitude of 10cm flux; (characteristic of log of flux in units of 10**-22watt/m**2/hz) d) dynamic spectrum; (type ii = 1, continuum = 2, type iv with duration > 10 minutes = 3) e) magnitude of 200mhz flux; (characteristic of log of flux in units of 10**-22watt/m**2/hz)

Conjugate Points - Two points on the earth's surface, at opposite ends of a geomagnetic field line.

Continuum Storm (Ctm) - General term for solar noise lasting for hours and sometimes days.

Coordinated Universal Time (Utc) - By international agreement, the local time at the prime meridian, which passes through Greenwich, England. Therefore, it is also known as Greenwich mean time, or sometimes simply universal time.

Corona - The outermost layer of the solar atmosphere, characterized by low densities (<1.0e+09/cc) and high temperatures (>1,0e+06deg.k).

Coronal Hole - An extended region of the corona, exceptionally low in density and associated with unipolar photospheric regions.

Coronal Rain (Crn) - Material condensing in the corona and appearing to rain down into the chromospheres as observed in h-alpha at the solar limb above strong sunspots.

Coronal Transients - A general term for short-time-scale changes in the corona, but principally used to describe outward-moving plasma clouds.

Cosmic Ray - An extremely energetic (relativistic) charged particle.

CRAF - Comet Rendezvous / Asteroid Flyby mission, cancelled.

Crochet - A sudden deviation in the sunlit geomagnetic field (h component; see geomagnetic elements) associated with large solar flare x-ray emission.

CRS - Cosmic Ray Subsystem, high-energy particle instrument on Voyager.

CRT - Cathode ray tube video display device.


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