(ek, sen tris’ ∂ t∂) 1. The ratio of the focus-to-center distance to the length of the semimajor axis for an ellipse;
FIG. E-12. 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
= eccentric anomaly
when satellite is at S
. The polar equation of an ellipse with one focus at the origin is
; 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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