Coordinates : locations of stars
Definitions:
1)celestial equator (circle on sphere in plane of earth’s
equator
2)north celestial pole (where earth’s axis intersects
celestial sphere)
â
position
of star: measure 2 angles on celestial sphere
Angles :
Declination (d)
– degrees North or South from celestial equator
(like
latitude)
Right Ascension (RA, a)
– angle* measured eastward (counter-
(like longitude) clockwise) along celestial equator
*RA in hrs, mins, secs (24 hr = 360o)
Earth rotates ccw
once in 24 hrs
\Celestial sphere rotates 15ocw
each hr