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TIP:
Don’t be intimidated by
the geometry. Hands-on
experience will help you
understand the concepts
better.
Since the celestial sphere completes a full rotation in 24 hours,
it follows that: 24 h = 360°, 1 h = 15°, 1 min = 15’, and 1 sec =
15”. The declination (
δ
, DEC, or D) is measured along the
hour circle (perpendicular to the equator, passing through the
celestial poles) passing through the star from the point it
intersects the equator, it is in degrees. The right ascension
(α, RA or R) is measured on the equator from the gamma
point in the direction opposite to the direction of the motion of
the star. It is in hours, minutes and seconds. Gamma point is
the intersection of the hour circle and the celestial equator.