On 22 August in DR position LAT 29° 41.8' N,...

Study

Question 1 of 2066636eea28f7522a1c51ace5

On 22 August in DR position LAT 29° 41.8' N, LONG 33° 15.5' W, you take an ex-meridian observation of the Moon's upper limb at upper transit. The chronometer time of the sight is 08h 00m 02s, and the chronometer error is 02m 20s slow. The sextant altitude (hs) is 74° 32.4'. The index error is 1.5' off the arc, and your height of eye is 48 feet. What is the latitude at meridian transit?

Back

Question 1 of 20

66636eea28f7522a1c51ace5

No comments yet

Be the first to share your thoughts!

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

🔍 Key Concepts

• Meridian altitude method for latitude: relationship between observed altitude (Ho), zenith distance (Z) and declination (Dec) at upper transit • Altimeter corrections for the Moon: index error off the arc, dip, main altitude corrections (refraction, parallax, semi-diameter, etc.), and using upper limb • Same name / contrary name rule between latitude and declination when finding latitude from meridian altitude

💭 Think About

• First, work carefully from hs to Ho: how do you apply an index error that is off the arc, how do you compute dip for 48 ft, and what special corrections are needed for a lunar sight of the upper limb? • Once you have Ho, think about the meridian altitude triangle: what is the zenith distance Z, and how is it related to Ho? Then, depending on whether the Moon’s declination is in the same hemisphere as you or opposite, do you add or subtract Z to get latitude? • Because it is an ex-meridian observation, ask yourself: how close to meridian passage are you likely to be, and is the ex-meridian correction likely to be large or small compared with the spread in the answer choices?

✅ Before You Answer

• Compute and write down the fully corrected Ho (observed altitude) before touching latitude – make sure each correction has the correct sign. • Confirm whether your latitude and the Moon’s declination are the same name (both N or both S) or contrary; this decides whether you add or subtract Z. • Estimate if any ex-meridian correction you would apply is of the order of a few tenths of a minute, a few minutes, or bigger – compare that scale to how far apart the multiple-choice answers are.

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

Quick actions

— No credit card needed