1 - NGA

;
by a shutter or other device to provkie precise
timing and ofiematlon data for geodetic
ok6enwfions of aaroapaca vehwes against a
eiellar beckgfoumf.
chord-1. (mute auweying) Chord used in
highway and other surveys to Miite a straight
line between two poinfa on a curva. ragatiless
of lhe distance between them. 2. In auweying
and geomeIry, a straight Ilne joining any two
points on an arc, came, clrcwrderenca, or
surface.
MIL-HDBK-850
chorographlc map-Any map repreaanting
large regions, countries, or continents on a small
scale. Atfas and small-emla wall maps belong In
mis class. .
chromatic aberr@tlon—See lateral
chromatic aberration; Iongltudlnal
chromatic aberration.
chmmatlc colors< olors eficiting hue.
chromatlclty coordlnatas—The proportions
of stamlard components required for color
malch, used as an ordinate and abscissa to
represem mlor in a chrornaticity d~Oram.
Chmmatlclty dlagrarm-A plane diagram
formed by pkc.ning one of the chromaticity
Coordinate against another.
chromatlclty—A compxjite of dominant
wavelength and purity.
chronograph-An instrument for producing a
graphical record of time as ahown by a clock or
other dev’kx. In uee, a chronograph produces a
double record: the firer is made by the
associated ckIc& and forma a continuous time
SCSle wlfh si@ficam marka Indkating periodic
beats of the tlmekaepar: the second is made by
some external agency, human or mechanical,
and records the occurrence of an event or of a
seties 01 eveme.
chronometer correction-See clock
corractlon.
chronometer error—The amount by which
the chronometer diem from the correcf time,
chronometer rata-See clock rate.
chronometer-A portable timekeeper wiih
compensated balance, capable of showing time
42
wifh extreme precisbn and accuracy. S8s afeo
break-clrcult chronometer; hack
chronometer.
clne thaodoltMt-A photograph tracking
Inetrumsnf which ramrda on each film frame the
targel and Ihe azimuth and elevation angles of
the OptbSf isxis 01 the inSfmMSM.
circle of contusion-(optics) The circular
image of a distant point object as termed in a
total plane by a tans. A distam point object
(a.g., a star) Is Imaged In a focal plane of a lane
as a circle 01 flfrlle sixa, because 01 such
conditions as: (1) the focal plane% not being
placed al the point of sharpasl focus: (2) the
effed of calain ebemations; (3) ditfractbn at the
lens; (4) grain in a photographic emulsfon:
arallor (5) pmr workmanship in the manufacture
of the lens.
circle of declination-S’ee hour circle.
circle of equal altltuda-See pamllel of
altltude.
circle of aqual declination—See parallel
of declination.
circla of tatlturte-1. A great circle of the
celestial sphere through the ecliptic poles, and
henca Wpendlcular to tha ptane of the actipfic,
2. A meridian along which latitude is measured.
circle of Iongltuda-1. A circle of tha
celestial sphere, parallel to the ecliptic. 2. A
circle on the suriace of Ihe Earth, parallel 10 the
plane of the Equatoc a parallel, afeng which
Iocgitude is measured. Also called parallal of
Iatltude.
clrcla of parpetual apparition-That circle
of the celestial sphare, centered on the polar
axis and having a polar dktarrce from the
elevated pole a~roxirnataly equal to the
latitude Of the obsewer, whhin which celestiaf
bodes do no! act. See also clrcla of
perpetual occultation.
circle of perpetual occuftatfort-That circle
of Ihe celestial sphere, centered on the polar
axis and having a polar distance from the
depreseed pole approxlnrafely equal to the
latitude of the observer, whhln which celestial
bodies do not rise. See also clrcla of
perpetual apparition.
circle of poaltion—A small circle on the globe