One (usually the vernal equinox) of the two points on the celestial sphere in which the celestial equator intersects the ecliptic at the time of an observation. Both the celestial equator and the ecliptic rotate in inertial space. The epoch (date) as well as coordinates of the points of inter-section must therefore be given in order to specify completely the locations of the equinoxes. The epoch is specified either by giving the Besselian year and fraction or by using the words of date, implying that the epoch is that of the instant of observation.