On 10 October your 0930 zone time position is LAT 25° 00.0' S, LONG 164° 38.6' W. Your vessel is on course 180° T at a speed to 10.0 knots. What is the zone time of local apparent noon (LAN)?
• Local apparent noon (LAN) occurs when the Sun crosses your local meridian (Sun on your longitude) • Relationship between Greenwich Hour Angle (GHA) of the Sun and your longitude at LAN • How to convert between GMT/UT and zone time using the correct time zone for 164° 38.6' W
• Think about what condition must be true between the Sun’s GHA and your longitude at the instant of LAN • How can you estimate the approximate GMT of LAN from the Nautical Almanac for 10 October, then refine it for your exact longitude? • Once you have GMT of LAN, what is the correct zone description (ZD) for 164° 38.6' W, and how do you apply it to get zone time?
• Be sure you are using the correct date (10 October) and year in the Almanac for the Sun’s data • Double-check you have the right sign for west longitude when relating it to GHA and to the zone description • Confirm that the zone description (ZD) you use corresponds to the standard 15°-wide time zone band that includes 164° 38.6' W
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