Celestial Navigation · Sextant — Adjustable Errors
Which sextant error is removed by adjustment of the index mirror so its plane is parallel to the horizon glass?
- AIndex error✓ Correct
- BPerpendicularity error (frame and index mirror)
- CSide error (horizon glass)
- DCollimation error
Explanation
Index error is removed (or measured) by making the index and horizon mirrors parallel when the index is at zero. Perpendicularity error involves the index mirror being square to the frame; side error involves the horizon glass being perpendicular to the frame; collimation involves the telescope axis.
Authority: Bowditch (Pub. No. 9), sextant adjustments and errors
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