Observer
# 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
* The Observer (disambiguation), any of various periodicals

## Science

* Observer (general relativity)
* Observer (meteorological)
* Observer (physics)
* 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'
