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.
Used with permission of the author. A diagram of the Celestial Sphere surrounding the earth showing the Celestial Equator, the North Celestial Pole, and lines of Right Ascension (analogous to longitude) and Declination (analogous to latitude). Also shown are the Big Dipper, Polaris (at the NCP), and Orion.