What is the primary purpose of the circular level on the Aiming Circle?

The primary purpose of the circular level on the Aiming Circle is for coarse leveling. Coarse leveling involves the initial adjustment of the aiming device to ensure it is approximately level before more precise adjustments are made. This step is crucial because an accurate level position is essential for effective aiming and accuracy in gunnery operations. The circular level allows operators to quickly assess and adjust the orientation of the Aiming Circle in a broader sense, ensuring that subsequent fine adjustments and angle measurements can be made from a stable base.

Fine leveling, angle adjustment, and standard calibration are additional steps or tasks that may be performed during the setup process, but they are not the primary function of the circular level, which is specifically designed to provide a basic level check and adjustment.