(ek, sen tris’ ∂ t∂) 1. The ratio of the focustocenter distance to the length of the semimajor axis for an ellipse;
FIG. E12.
Ellipse terminology. An ellipse is the locus of points for which the sum of the distances from the two foci is constant. A satellite follows an elliptical path about a body at one focus. If
a = semimajor axis,
b = semiminor axis,
eccentricity $=\varepsilon =c/a=(2ff^{2})^{1/2}=[1(1/E)^{2}]^{1/2}$;
ellipticity $=E=a/b=1/(1f)=(1\varepsilon ^{2})^{1/2}$;
flattening $=f=(ab)/a=11/E$; and
$\theta$ =
eccentric anomaly when satellite is at
S. The polar equation of an ellipse with one focus at the origin is
$\rho =\varepsilon h/(1\varepsilon \cos \phi )$; where
h = distance from the focus to a directrix line.
2. The condition occurring when the source is not located at (or perpendicularly offset to) the center of what is intended to be a split spread. This occurs on marine records when a separate source boat is employed.
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