circle of position

circle of position

An imaginary small circle on the Earth's surface on which an observer is located and that is centered on the substellar point of a particular star. Its radius is equal to the zenith distance of the star. The star will thus have the same zenith distance from every point on the circle of position.

circle of position

[′sər·kəl əv pə′zish·ən]
(navigation)
A circular line of position, used most frequently with reference to the circle of equal altitude surrounding the geographical position of a celestial body, but also used to refer to the lines of position produced by the distance-measuring equipment system.

circle of position

A small circle on the globe (earth) in which, at every point at the instant of observation, the observed celestial body (sun, star, or planet) has the same altitude and, therefore, the same zenith distance. Also called a circle of equal altitude