The values of the Greenwich hour angle and...

Question 1 / 2066636ee928f7522a1c51a561

Question 1 of 2066636ee928f7522a1c51a561

The values of the Greenwich hour angle and declination, tabulated in all almanacs, are for the _________.

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Question 1 of 20

66636ee928f7522a1c51a561

The values of the Greenwich hour angle and declination, tabulated in all almanacs, are for the _________.

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🔍 Key Concepts

• Greenwich hour angle (GHA) is an angle measured from the Greenwich meridian to the hour circle of the body • In the Nautical Almanac, GHA and declination are geometric positions used for ALL observers, not dependent on limb you sight • The difference between a body’s true center and what you actually measure (upper or lower limb) with a sextant

💭 Think About

• Ask yourself: when astronomers and almanac compilers describe the position of a celestial body in space, do they define that position by its limb or by a specific geometric point? • Think about how you handle a lower‑limb Sun sight in sight reduction: which part do you correct with semi‑diameter and which part is given directly in the almanac? • Consider whether the almanac would need separate GHA/Dec values for upper limb, lower limb, Sun, Moon, planets, and stars—or if one common reference point is more practical.

✅ Before You Answer

• Verify what GHA actually represents: an angle to the body’s hour circle associated with a single point on the body • Recall that declination is defined like latitude on the celestial sphere and is referenced to a specific point of the body, not its apparent edge • Confirm which corrections (e.g., semi‑diameter) are applied by the navigator, and which fundamental position is given directly in the almanac

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Question 1 of 20

The values of the Greenwich hour angle and declination, tabulated in all almanacs, are for the _________.

centers of the various celestial bodies

lower limb of a celestial body

upper limb of a celestial body

lower limb of the Sun and Moon; center of the stars and planets

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Question 1 / 2066636ee928f7522a1c51a561

Question 1 of 2066636ee928f7522a1c51a561

The values of the Greenwich hour angle and declination, tabulated in all almanacs, are for the _________.

Back

Question 1 of 20

66636ee928f7522a1c51a561

The values of the Greenwich hour angle and declination, tabulated in all almanacs, are for the _________.

No comments yet

Be the first to share your thoughts!

If the question has a related picture, it will appear here.

🔍 Key Concepts

💭 Think About

✅ Before You Answer

👋 Hi! I'm Genie, your AI study assistant. How can I help you with this question?

Quick actions

— No credit card needed