Observer

An observer is one who engages in observation or in watching an experiment.

Observer may also refer to:

Computer science and information theory

 * In information theory, any system which receives information from an object
 * State observer in control theory, a system that models a real system in order to provide an estimate of its internal state
 * Observer pattern, a design pattern used in computer programming

Fiction

 * Observer (novel), a 2023 science fiction novel by Robert Lanza and Nancy Kress
 * Observer (video game), a cyberpunk horror video game
 * Observer (Mystery Science Theater 3000), a fictional television character
 * Observers, beings in the television show Fringe

Military

 * Air observer, an aircrew member
 * Artillery observer, a front line personnel who directs fire discipline for artillery strikes
 * Royal Observer Corps, a civil defence organisation, originally tasked with reporting enemy aircraft
 * Observer, a non-participating officer, or umpire, tasked with observing the actions of soldiers during a field training or military exercise

Music

 * "Observer", a song by Gary Numan on his album The Pleasure Principle
 * "The Observer", a track from The Flaming Lips' 1999 album The Soft Bulletin
 * The Observers, an alternative name for reggae session band Soul Syndicate
 * Niney the Observer (born 1951), Jamaican record producer and singer

Publications

 * Observer.com, an online-only version of the weekly newspaper The New York Observer
 * Sunday Observer (Sri Lanka), a weekly newspaper
 * Observer (APS), a member magazine of Association for Psychological Science

Science

 * Observer (general relativity)
 * Observer (meteorological)
 * Observer (quantum physics)
 * Observer (special relativity)
 * Observational astronomy

Other uses

 * Observer status, granted by an organization to allow a non-member limited participation
 * An election observer, one who assists in election monitoring
 * A game official sometimes used in the sport Ultimate
 * The Observer type in the Enneagram of Personality model
 * Donald Alaster Macdonald (1859–1932), Australian journalist who wrote under the pseudonym 'Observer'