Celestial Navigation · Sight Reduction — Z to Zn
In north latitude a sight reduces to Z = 110° with LHA = 040°. What is the azimuth Zn used for plotting?
- AZn = 180° + Z = 290°
- BZn = Z = 110°
- CZn = 180° − Z = 070°
- DZn = 360° − Z = 250°✓ Correct
Explanation
In north latitude: if LHA > 180°, Zn = Z; if LHA < 180°, Zn = 360° − Z. Here LHA = 040° (< 180°), so Zn = 360° − 110° = 250°. The rules are reversed (about 180°) for south latitude.
Authority: Pub. No. 229 / Pub. No. 249, Z to Zn conversion; Bowditch (Pub. No. 9)
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