When entering an altitude in STELLA, which height is being used?

When entering an altitude in STELLA, the correct height being utilized is the observed altitude. The observed altitude refers to the angle that an observer measures, usually taken from their own position, such as when they are observing celestial bodies or landmarks. This measurement accounts for factors like atmospheric refraction and the observer's height above the waterline.

This choice is fundamental because it reflects the actual data recorded from navigation instruments or observation techniques. Unlike the estimated altitude, which may be based on predictions or theoretical values, the observed altitude is the direct observation that comes from tools like sextants or radar. This aspect is crucial for accurate navigation and calculations in sea navigation, where precision is vital for safe and effective traversal of maritime routes.

The other options, while related, do not correctly define the value inputted into STELLA when entering the altitude. Thus, the observed altitude is the most accurate and contextually relevant choice.