Your 0000 zone time position on 13 June is LAT 24° 35' N, LONG 142° 26' E. Your vessel is on course 245° T, speed is 13.5 knots. What is the zone time of sunrise?
• Sunrise calculation from the Nautical Almanac (using date and DR latitude/longitude) • Converting between GMT (UT), local mean time (LMT), and zone time (ZT) using the zone description (ZD) • Effect of longitude and vessel’s motion on the time of sunrise
• First, at 24° 35' N on 13 June, what is the approximate GMT (or LMT) of sunrise from the almanac before any longitude or motion corrections? • Given LONG 142° 26' E, what is the correct zone description (ZD), and how do you apply it to convert between GMT and zone time? • How much does the vessel move between your chosen reference time and sunrise along the east–west (longitude) component of the track, and how does that change the sunrise time?
• Be sure you are using the correct date (13 June) and latitude (24° 35' N) for the sunrise page in the Nautical Almanac, not a nearby date or latitude band. • Confirm the correct sign and magnitude of ZD for a longitude of 142° 26' E (is it plus or minus, and is it 9 or 10 hours?). • After applying motion and longitude corrections, recheck whether the final time is reasonable for sunrise in mid‑June at about 24° N (should it be closer to very early morning or nearer to 0600?).
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