Equatorial coordinate system

When equatorial coordinate system is referred to two geocentric coordinate systems used in the spherical astronomy on the celestial sphere, the rotating and the fixed equatorial coordinate system. The reference plane is in both cases the plane of the celestial equator. Is the reference point on the celestial equator at the vernal equinox rotating system, the stationary system, the intersection between the celestial equator and the meridian of the observing site.

Description

The position of an object in the sky, so on the imaginary celestial sphere, in the middle is the earth is given by two polar coordinates from Earth:

First spring equinox as a reference point: For observers on Earth, the starry sky daily rotates with the vernal equinox once around the Earth. Therefore, it is spoken by a rotating system.

• Declination ( angular distance from the equatorial plane; positive sign for the Northern Hemisphere )
• Right Ascension ( angular distance from the vernal equinox, a star with a larger right ascension immigrated later through the meridian as a smaller right ascension )

2 meridian section of the observer as a reference point: so-called stationary system (as long as the observer is stationary)

• Declination (angle distance from the equatorial plane )
• Hour angle ( angular distance from the meridian, west of 0 ° from increasingly, to the east of 360 ° and it falls off )