"observation" - key terms from Wikipedia

aerial observation
artillery observation
earth observation
earth observation satellite
earth observation satellites
election observation
forward observation pods
given the observation
light observation helicopter
observation
observation aircraft
observation angle
observation area
observation balloon
observation balloons
observation bar
observation deck
observation decks
observation helicopter
observation helicopters
observation hill
observation of an unusual object
observation of bird
observation of dislocations
observation of the sun
observation of the transit
observation period
observation post
observation posts
observation room
observation statements
observation teams
observation terms
observation tower
observation wheel
participant observation
pilgrim observation gallery
reflective observation
under observation
variance of an observation