In what order should the following sextant adjustments be made? I. Make telescope parallel to frame of sextant. II. Set horizon glass perpendicular to frame of sextant. III. Make index mirror and horizon glass parallel when index arm is set at zero. IV. Set index mirror perpendicular to frame of sextant.
• Sextant adjustment sequence – which errors each step is meant to remove (perpendicularity error, side error, index error) • Relationship between mirrors, frame, and telescope in a correctly adjusted sextant • Which adjustments depend on others already being correct
• Think about which components must be trued (made right with the frame) before you can reliably make the mirrors parallel at zero index. • Ask yourself: can you correctly align the telescope if the mirrors and frame are still out of square, or does that need to wait until last? • Consider which adjustment is the basic ‘foundation’ (referenced to the frame), which one comes next, and which is the final small correction before using the sextant.
• Identify which step removes perpendicularity error of the index mirror relative to the frame. • Identify which step removes side error (tilt between telescope line of sight and horizon glass). • Confirm which step adjusts index error (making the two mirrors parallel when the index reads zero) and make sure this comes only after the fundamental frame‑related adjustments.
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