Celestial Navigation · Sight Reduction — Assumed Longitude
When reducing a sight with Pub. 229 or 249, the assumed longitude is chosen so that:
- AIt exactly equals the DR longitude
- BThe resulting LHA is a whole degree✓ Correct
- CThe latitude becomes a whole degree
- DGHA equals zero
Explanation
The assumed longitude is selected (nearest the DR) to make LHA come out as an exact whole degree, since the sight-reduction tables are entered with integral degrees of LHA. The assumed latitude is likewise the whole degree of latitude nearest the DR.
Authority: Bowditch (Pub. No. 9), Sight Reduction
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