CST Level 1 Land Surveyor Certification Practice

What is the starting position for measuring zenith angles?

1. From the horizon level

2. From the north direction

3. From the 12 o'clock position

4. From the benchmark elevation

The correct answer is: From the 12 o'clock position

The starting position for measuring zenith angles is from the 12 o'clock position, specifically at the zenith point, which is directly overhead. Zenith angles are measured from this vertical point, allowing surveyors to determine the angle between a measured point in the sky and the vertical axis. This method provides a consistent reference for capturing the orientation of objects, such as stars or other celestial points, in relation to the observer's position. This choice is grounded in the standard practice of surveying and aligns with the understanding that angles in a spherical coordinate system, such as those used in geodesy, are typically established with the zenith directly above the observer as the starting point. In measuring zenith angles, it’s critical to consider such positional standards for accuracy and uniformity in data collection, as this facilitates comparisons across different observations.