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.
Geographic coordinate system. A geographic coordinate system (GCS) defines locations on the earth using a three-dimensional spherical surface , it is a reference system that uses latitude and longitude to identify locations on a spheroid or sphere. A datum, prime meridian, and angular unit are parts of a GCS.