On 3 January your 1759 zone time DR position...

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Question 1 of 2066636eea28f7522a1c51adee

On 3 January your 1759 zone time DR position is LONG 60°53.2' W. At that time you observe Polaris with a sextant altitude (hs) of 22°55.8'. The chronometer time of the sight is 09h 57m 10s, and the chronometer error is 02m 26s slow. The index error is 2.9' off the arc, and the height of eye is 52.5 feet. What is your latitude by Polaris?

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🔍 Key Concepts

• Polaris (Pole Star) latitude method – how Polaris’ altitude relates to your latitude in the Northern Hemisphere • Correcting sextant altitude: index error, height of eye (dip), and small corrections from tables to find Ho • Using GHA Aries and LHA to get the Polaris corrections for date and longitude (January 3, longitude 60°53.2' W)

💭 Think About

• First, turn the sextant altitude (hs) into an observed altitude (Ho). What corrections must you apply, and with what sign, for index error and height of eye? • Think about how close Polaris is to the true North Celestial Pole. How do you start from Ho and then apply small table corrections using your LHA and date to arrive at latitude? • Once you compute latitude, compare it to the four answer choices. Are you expecting something slightly more or less than the altitude of Polaris, and by about how much at this longitude and date?

✅ Before You Answer

• Be sure you apply index error correctly: it is given as "off the arc"—does that mean add or subtract from hs? • Confirm that dip (height of eye) is always subtracted from hs when converting to apparent altitude (Ha). • Verify you are using the correct LHA for Polaris corrections for 3 January and longitude 60°53.2' W (West longitudes usually make LHA greater when GHA is smaller, so track the signs carefully).

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