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From which point on the celestial equator is right ascension measured?
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Astronomical map
Star trails over banksia trees, in Gippsland, Vic., Austl. The south celestial pole, located in the constellation Octans, is at the centre of the trails.
Right ascension is measured eastward from the vernal equinox along the celestial equator.12
This reference point is also historically referred to as the first point of Aries. Although the precession of the equinoxes has shifted its actual location into the constellation Pisces, the term remains in use as the zero point for this astronomical coordinate system.32