On 23 August in DR position LAT 24° 22.0' S,...

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Question 1 of 2066636eea28f7522a1c51ad55

On 23 August in DR position LAT 24° 22.0' S, LONG 64° 55.3' E, you take an ex-meridian observation of the Moon's upper limb at upper transit. The chronometer time of the sight is 02h 15m 04s, and the chronometer error is 01m 06s fast. The sextant altitude (hs) is 48° 03.6'. The index error is 2.0' on the arc, and your height of eye is 60 feet (21.0 meters). What is the latitude at meridian transit?

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Question 1 of 20

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🔍 Key Concepts

• Ex-meridian (ex-meridianian) sights of the Moon and how they relate to meridian transit latitude calculations • Corrections from sextant altitude (hs) to observed altitude (Ho) including index error, dip, and main altitude corrections for the Moon’s upper limb • Using the Declination of the Moon at upper transit and applying the correct sign and relationship between zenith distance and latitude

💭 Think About

• After you correct hs to get Ho, what is the zenith distance (90° - Ho), and how does this relate to latitude when the body is on or very near the meridian? • Given that this is an ex-meridian sight, how close in time is the observation to upper transit, and what kind of small correction might be needed to adjust the latitude from a true meridian altitude? • Is the Moon’s declination north or south on 23 August, and is it numerically greater or less than your DR latitude? How does that change whether you add or subtract declination and zenith distance when solving for latitude?

✅ Before You Answer

• Be sure you correctly apply index error sign: "on the arc" versus "off the arc" and how that affects hs. • Confirm the dip correction for a 60 ft (21 m) height of eye and subtract it with the correct sign when going from hs to Ha. • Verify you are using the proper Moon altitude corrections (limb, SD, refraction, parallax) and that you check whether the resulting latitude is reasonably close to the DR latitude (24° 22.0' S).

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