A marine sextant has the index arm set at...

Question 1 of 2707066636ee928f7522a1c519b93

A marine sextant has the index arm set at zero and the reflected image of the horizon forms a continuous line with the actual image. When the sextant is rotated about the line of sight the images separate. The sextant has which error?

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Question 1 of 27070

🔍 Key Concepts

• Sextant errors related to mirror alignment (index error, side error, error of perpendicularity, centering error) • What it means when the horizon lines up at one orientation but not when the sextant is rotated • Which specific error is detected by rotating the sextant about the line of sight while viewing the horizon

💭 Think About

• Ask yourself: If the horizon appears as one continuous line at zero but breaks apart when you rotate the instrument, what does that say about the alignment of the mirrors relative to the frame and line of sight? • Think about which error is checked/corrected by bringing the direct and reflected horizons into one straight line and then rotating the sextant slightly side to side. • Match each answer choice to its usual test: which one specifically involves rotating the sextant around the line of sight while viewing the horizon?

✅ Before You Answer

• Identify which test is described: horizon continuous at zero, then rotate about the line of sight and watch for separation. • Review how side error is normally detected versus how error of perpendicularity is detected—do they both use rotation, and if so, in what way? • Confirm which error involves the index mirror not being exactly perpendicular to the plane of the sextant, and what visual effect that has on the horizon line when you rotate the instrument.