The circle of equal altitude  also called circle of position , CoP , is the real line of position in celestial navigation. It is defined as the locus of points on the Earth on which an observer sees a star, at a given time, with the same observed altitude. It was discovered by the American sea-captain Thomas Hubbard Sumner.
The circle of equal altitude , also called circle of position (CoP) , is the real line of position in celestial navigation. It is defined as the locus of points on Earth on which an observer sees a star, at a given time, with the same observed altitude. It was discovered by the American sea-captain Thomas Hubbard Sumner.
A
,
R
, CoP
(CoP)
D
the