Post-concussion syndrome. Post-concussion syndrome, also known as postconcussive syndrome or PCS, is a set of symptoms that may continue for weeks, months, or a year or more after a concussion â a mild form of traumatic brain injury (TBI).
The Equatorial (Celestial) Coordinate System. Equatorial coordinates, also called simply celestial coordinates, are the standard coordinate system for the sky. It is meant for the fixed sphere of the stars within which the Earth and Sun move.
celestial equator. n. 1. (Astronomy) the great circle lying on the celestial sphere the plane of which is perpendicular to the line joining the north and south celestial poles. Also called: equinoctial or equinoctial circle.elestial equator. n. 1. (Astronomy) the great circle lying on the celestial sphere the plane of which is perpendicular to the line joining the north and south celestial poles. Also called: equinoctial or equinoctial circle.