The objective of an impact registration is to get spotting's of how many rounds along the observer-target line?

The objective of an impact registration is to accurately determine the range to the target by observing how rounds land in relation to the target. By getting four rounds, specifically two that impact over the target and two that land short, the observer can effectively establish a more precise range bracket around the target. This methodology allows for a better assessment of the range correction needed for subsequent fire missions.

Gathering two rounds over the target provides insight into the maximum range, while two rounds short help establish the minimum effective range. This collection of data gives the fire support team a comprehensive understanding of the dispersion and aids in adjusting fire accurately. Using four rounds ensures that the observer can make a well-informed adjustment to engage the target correctly, increasing the effectiveness of artillery fire.