A Sniper-Spotter Team consists of two people, a sniper and a spotter. Both of them are usually fully qualified as a sniper, but they have different duties. These duties are often rotated for various reasons, for example to reduce eye fatigue of the spotter during observation and to reduce arm fatigue. Sniper and spotter are also referred to as marksman and observer; however, a sniper is not a marksman, which has a different role in the military. A marksman operates within a unit and is usually called upon when accurate shooting is needed while a sniper normally operates individually in a sniper and spotter team and are often deployed with a specific tactical, or possibly even strategic, objective.
The spotter detects, observes, and assigns targets and watches for the results of the shot. Using his spotting scope, he will also read the wind by using physical indicators and the mirage caused by the heat on the ground. Also, in conjunction with the shooter, he will accurately make calculations for distance, angle shooting (slant range), mil dot related calculations, correction for atmospheric conditions, and leads for moving targets.
He also provides the team security, therefore he is usually armed with an assault rifle. It is often the case that the sniper rifle is assigned exclusively to a single person, therefore in the case of rotation the spotter carries two weapons.
The spotter is also usually tasked to ensure proper communication with adjacent units, adjusting how the indirect fire and close air support will work for the team.
As a Corporal, Avery Junior Johnson worked with an unnamed Marine, potentially Nolan Byrne during an operation to assassinate Jerald Mulkey Ander on Harvest in 2502. Johnson was the sniper, while the other Marine was the spotter. However, a Spartan-II, Linda, preferred to work alone.