### equatorial coordinate system

(latitude/longitude-like system for the celestial sphere)

The **equatorial coordinate system** is a
spherical coordinate system used for directions in the
celestial sphere,
fixed to the stars/constellations as seen from Earth.
Elements:

It (and the closely related International Celestial Reference System)
is commonly used for planetary orbit calculation and
its coordinates are those generally used in identifying and naming
objects (e.g., J designators).

The Earth's precession results in a slow but never-ending
shift in the equatorial coordinates that indicate a point on the
celestial sphere: on the order of an arcsecond per month. This is a
prime reason for specifying an epoch.

(*coordinate system,equatorial,celestial sphere,Earth*)
http://en.wikipedia.org/wiki/Equatorial_coordinate_system

**Referenced by:**

celestial coordinate system

celestial sphere

ephemeris

equinox

galactic north

International Celestial Reference System (ICRS)

J designator

index