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eccentricity of spheroid (elllpeold) of
revolution-The eccmtrklty of an ellpse
forrnirrg a meridian aactbn of the spheroid.
.,, .,.. ..
MIL-HDBK-850
eccentrlclt y—1. Amount of deviation from a
center. See also eccentric stetlon. 2.
(surveyors cumpass) An ettect caused by ona
or a combination of the folbwirtg conditions: (1)
a straight line through Itra ends of the magnetic
needle fails to pass through the canter of
rotation of the needle; (2) the center of rotation
of the needle is not coinckient with the center of
figure ot the graduated circle; (3) the tine of sight
tailS 10 peas through the vertbal axis of the
instrument. 3. The ratio of the dtslances from
any pc.im of a @nit sect”k.n to a locus and lhe
ccrrraspardlng dkecfrlx.
ecllptlc
latlttsrJe-Se e celeetlel Ismtude.
ecllptlc longltude—See celeetlal
Iongltude.
eCllptlC merldlen—A circle on the celestial
sphere containing points 01 Ihe same celes!lal
Iongftude.
ecllptlc nods-See node.
ecllptlc parallel-A circle on the celeslial
sphere mntaining points of the same celestiel
Iatltude.
ecllptlc pCrlar dlatance-The complement of
the celestial Ialiiude.
eccentric-Nol having the same cenler.
ecllptlc pole-On the celestial sphere, eiiher
echo ●ounder—An echo sounding instrument
of the two points 90” from the ecliitic.
used for depth measurements in water. ecllptlc system 01 coordinates—A Sy6tem
echo eoundlng—A method tor measuring
depths by rssordlrrg the tlma intewal required for
sound waves to go from a source of sound near
the surfsce to the bertom and back again.
echo tlmlng—The measurement of time
required for a short train ot energy waves to
travel the round trip path from en originating
station to a raflecfor or transponder.
echogrem-A graphk record of depth
meaauremems obtained by echo soundhg
equipmem. Called !athog ram when obt sined
from a Fathometer echo sounder.
echo—See blip.
ecllpaa year—The Imewal between two
successive conjunctions ot the Sun with the
same node of the Moon’s orbit.
eclipet+l. The reduction in visibitit y or
dissppearamxr of a nonluminous body by
passing into the shadow cast by another
nonluminous body. 2. The apparent cutting off,
wholiy or partially, of the fight horn a luminous
body by a dadr body coming between If and the
obserwer. See also annular ecllpae; iunar
eclfpee; soinr eclipee.
ecllptlc coordinate eystem—See ecllptlc
eyalem of coordlnatea.
80
Of Curvilinear CeleStial coordinates which uses
the ectiptlc as the primary retererrce plane and
the ecliptic meridian through the vernal equimx
ss the secondary plane. The points 90” fmm the
ecliptic are the norlh and .aouth .ecliplic poles.
Angular distance north or south of the ecliptic
analogous 10 latitude, is celestial Iatifude.
Celestial bngitude is measured eastward alOng
the ecliptic trom the vernal equinox through
360’.
ectlptlc—The great cimle formed Lrythe
intersection of the plane of the Eanh”s orbit
around the Sun (or apparent orbii O! the Sun
around the Earth) and Ihe celestiai sphere.
edge matcftlng-lhe comparison and
graphic adjustment ot features to obtain
agreement along the edges of adjoining map
sheets.
edge mating—Sac metchlng.
edge-l. (imagery) The boundary of an object
in a photograph or image, usually charactartzed
by a drastic change in the brightness value from
the immediate interior of the boundary to the
immediate exterior of the boundary. 2.
(Iopobay) A line used to represent the Iocatun
of a linear faature and the bordara of faOeS.
Edges may be topologicslly fintrad to males,
edges, and taces.
editing—The process of checftihg a map or