Celestial Navigation · Time — Zone Description West
Your DR longitude is 130°W. What is the zone description (ZD) of your time zone?
- A+9 (add 9 hours to ZT)✓ Correct
- B−9 (subtract 9 hours)
- C+8 (one zone too few)
- D+13
Explanation
Zone description = longitude ÷ 15, rounded to the nearest whole zone. 130 ÷ 15 = 8.67, rounded to 9. West longitude takes a plus sign: ZD = +9, meaning you add 9 hours to zone time to get GMT/UT.
Authority: Bowditch (Pub. No. 9), Time
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