Definition:North Polar Distance
Jump to navigation
Jump to search
Definition
Consider the celestial sphere $C$ with observer $O$.
Let $X$ be a point on $C$.
Let $X$ have declination of $\delta$.
The north polar distance of $X$, denoted $\operatorname {N.P.D.} x$, is defined as:
- $\operatorname {N.P.D.} x = 90 \degrees - \delta$
That is, the north polar distance of $X$ length of the arc from the north celestial pole $P$ along the vertical circle through $X$.
Also known as
North polar distance is also known as codeclination.
Also see
- Results about north polar distance can be found here.
Sources
- 1976: W.M. Smart: Textbook on Spherical Astronomy (6th ed.) ... (previous) ... (next): Chapter $\text {II}$. The Celestial Sphere: $19$. Declination and hour angle.
- 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): codeclination
- 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): declination (dec)
- 1998: David Nelson: The Penguin Dictionary of Mathematics (2nd ed.) ... (previous) ... (next): equatorial coordinate system
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): codeclination
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): declination (dec)
- 2008: David Nelson: The Penguin Dictionary of Mathematics (4th ed.) ... (previous) ... (next): equatorial coordinate system