On 29 July your 1930 zone time DR position...

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Question 1 of 2066636eea28f7522a1c51addb

On 29 July your 1930 zone time DR position is LONG 164°26.0'E. At that time you observe Polaris with a sextant altitude (hs) of 23°46.8'. The chronometer time of the sight is 08h 32m 18s, and the chronometer error is 02m 26s fast. The index error is 2.7' on the arc, and the height of eye is 56.0 feet. What is your latitude by Polaris?

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🔍 Key Concepts

• Using Polaris to find latitude in the Northern Hemisphere • Correcting sextant altitude (hs) to get observed altitude (Ho) (index error, dip, refraction, etc.) • Applying the Polaris correction using local hour angle (LHA) of Aries or approximate longitude/date method

💭 Think About

• How do you turn the sextant altitude (hs) into a true observed altitude (Ho) step by step? List each correction in order. • Once you have Ho of Polaris, how is that related to latitude, and what small corrections (for Polaris not being exactly at the pole and for your longitude/date) must be applied? • Given your DR longitude and date, should the Polaris correction make your latitude slightly larger or smaller than Ho, and by about how much (under 1°, around 1°, or several degrees)?

✅ Before You Answer

• Be sure you apply index correction with the correct sign ("on the arc" vs "off the arc") before anything else. • Convert height of eye in feet to dip in minutes of arc correctly and apply it with the right sign (dip is always subtracted from hs). • Confirm you are using a Northern Hemisphere Polaris formula/table, and that the final answer is north latitude and close in value to your corrected Ho.

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