At 1000 ZT 21 October your DR position is...

Question 1 of 2707066636eea28f7522a1c51a9e1

At 1000 ZT 21 October your DR position is LAT 29°00'N, LONG 134°40'E. Determine the computed altitude (Hc) of the Sun for the assumed position nearest to the above given latitude and longitude, given a chronometer time of 01h 00m 00s.

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Question 1 of 27070

🔍 Key Concepts

• Greenwich Hour Angle (GHA) and declination of the Sun for 21 October at 01h 00m 00s GMT/UTC from the Nautical Almanac • How to form an assumed position (AP) from a DR position for sight reduction tables (rounding latitude and longitude to whole degrees and nearest LHA hour if needed) • Using Sight Reduction Tables (e.g., HO 229/249) or calculator to find Hc from AP, LHA, and declination

💭 Think About

• First, convert the given local zone time (ZT) and longitude into GMT/UTC and then to chronometer time. Are you consistent about the sign of the longitude and the zone description? • From the Nautical Almanac, obtain the Sun’s GHA and declination at 01h 00m 00s and apply any needed corrections. How does this lead you to the Local Hour Angle (LHA) for your assumed position? • When you enter the sight reduction tables (or formula), how does a small change in LHA or latitude affect the computed altitude (Hc)? Which of the listed choices are most consistent with a mid‑morning Sun at about 29°N and 134°40'E in October?

✅ Before You Answer

• Verify the correct zone description (ZD) for 134°40'E and that 1000 ZT converts properly to 01h 00m UTC/chronometer time. • Check that the assumed latitude and assumed longitude you use match the nearest whole degree that standard sight reduction methods require. • Before picking an answer, estimate whether the Sun should be higher or lower than 45° at that date, time, and latitude to eliminate any clearly unreasonable Hc values.