When plotting a circle of equal altitude for...

Question 1 / 2707066636ee928f7522a1c519e56

Question 1 of 2707066636ee928f7522a1c519e56

When plotting a circle of equal altitude for a high altitude sight, the radius of the circle is determined by which formula?

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Question 1 of 27070

When plotting a circle of equal altitude for a high altitude sight, the radius of the circle is determined by which formula?

🔍 Key Concepts

• Circle of equal altitude definition in celestial navigation • Relationship between observed altitude (Ho) and zenith distance (z) • How 90° relates to zenith distance and altitude on the celestial sphere

💭 Think About

• Which quantity actually represents the radius on the Earth of a circle of equal altitude: altitude, zenith distance, or an angle related to them? • How is zenith distance (z) defined in terms of the observed altitude (Ho)? • Look at each option: which ones mix local hour angle or Greenwich hour angle, and are those angles used to set radius or something else (like position of the GP)?

✅ Before You Answer

• Confirm the definition: z = 90° − Ho for a celestial body • Identify which formula directly gives you zenith distance, not hour angle • Make sure the formula you choose produces a value that can logically serve as the radius of the circle of equal altitude (an angular distance from the geographic position of the body)

Question 1 of 27070

When plotting a circle of equal altitude for a high altitude sight, the radius of the circle is determined by which formula?

z - d

GHA - LHA

180° - GHA

90° - Ho

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