This post continues the ones here and here.
Realism considers what is perceived with full consciousness as reality. Apperception and reality correspond to each other. The role of theory is to clarify this correspondence, not to deny it. So realists understand observation to be correct, not to be altered by theory.
Anti-realism considers what is judged with full consciousness as reality. Judgment and reality correspond to each other. The role of observation is to clarify this correspondence, not to deny it. So anti-realists understand judgment to be correct, not to be altered by perception.
The proper observational frame of reference is at rest. Observers are unable to know the destination of a moving figure (a movement) but can accurately know its relative position or momentum. The proper traveler frame is in motion toward a destination (or away from a contra-destination, such as a workplace). Travelers are unable to know the relative position of any moving body but can accurately interrogate the relative progress toward a destination.
The light of the Sun is transmitted directly to Earth. The light of the Moon is reflected light; it is the light of the Sun re-transmitted. With sunlight the first leg of the trip is seen as instantaneous. With moonlight the second leg of the trip is seen as instantaneous. The observer sees an instantaneous object; the transmitter sees an instantaneous reflection.
The perfection of motion is to arrive at its destination. That is, a motion has the potential to become actualized at its destination as a movement. The persistence of a movement has the potential to keep moving and become actualized in a motion.
For Aristotle most phenomena have final causes, destinations. Motion is on the way to being at rest. For modern science most phenomena have no final causes, no destinations.
Observers know best where they are, their location. Travelers know best where they’re going, their velocity or momentum. These are like the position of a particle and frequency of a wave. Observers see particles coming at them. Travelers see waves trailing behind them.
Experimenters are like travelers or transmitters. They have a target or goal they are aiming toward. At first they are instigators, not observers, though in the end they observe. Real observers can be like this, too: they often begin with some observation in mind.