Field astronomy — when to observe Polaris to determine latitude In practical surveying and field astronomy, Polaris (the North Star) is most suitable for determining the observer's latitude when it is at which positional condition in its diurnal path?

Introduction / Context:
Surveyors frequently use Polaris because its declination is close to +90 degrees. At culmination (meridian transit), its altitude is directly related to the observer's latitude with minimal azimuth error, making it ideal for latitude determination.

Given Data / Assumptions:

• Observer is in the Northern Hemisphere.
• Polaris' declination is close to the north celestial pole.
• Meridian observations minimize azimuth-related complications.

Concept / Approach:

At meridian transit (culmination), the star lies on the observer's meridian. The observed meridian altitude of Polaris is approximately equal to the observer's latitude, adjusted by the small offset of Polaris from the pole and refraction. This is a standard method in astronomical positioning.

Step-by-Step Solution:

Verification / Alternative check:

Textbook procedures list meridian altitude of Polaris as the canonical latitude method; elongation is instead favored for azimuth determination of lines due to larger azimuth sensitivity there.

Why Other Options Are Wrong:

• (b) Elongation is best for azimuth, not latitude.
• (c) and (e) provide no advantage for latitude.
• (d) mixes two distinct use-cases; only culmination is ideal for latitude.

Common Pitfalls:

• Confusing the preferred condition for azimuth (elongation) with that for latitude (culmination).

Final Answer:

At culmination (upper or lower transit across the meridian).