In registration, deviation refinement is determined by adding the deviation spottings of the rounds establishing the two over and two short. Then what does the observer do to get an average deviation?

When determining the average deviation during registration, the observer needs to incorporate the deviations from the spottings of the rounds that were fired to establish the parameters for "two over and two short." To obtain an average deviation, the observer divides the total deviation by the number of deviation spottings, which is typically measured in meters. This step is crucial because it allows the observer to convert the collected deviations into a mean value that can be used to adjust subsequent fire missions for greater accuracy.

This means that after collecting the deviation data, the specific action taken involves dividing by a measure that translates these deviations effectively, which aligns with the use of meters. This method helps ensure that the corrections made during artillery fire are based on a sound mathematical average, leading to better-targeted adjustments and increased overall effectiveness in fire support operations.