Sextant and Compass Errors Midterm Topics TQ

_________is a double reflection instrument, used for measuring angles in then same plane.

• Marine Sextant

• Azimuth Circle

• Pelorus

• Binocular

The arc graduation in degrees from right to left on a sextant is from 0° t0 _____________.

• 180°

• 150°

• 120°

• 090°

Index mirror not perpendicular to frame.

• Error of Perpendicularity

• Side Error

• Collimation Error

• Index Error

Horizon Glass not being parallel to the index mirror at zero setting.

• Index Error

• Side Error

• Collimation Error

• Error of Perpendicularity

Horizon Mirror not perpendicular to frame.

• Error of Perpendicularity

• Side Error

• Collimation Error

• Index Error

Telescope not parallel to frame.

• Error of Perpendicularity

• Side Error

• Collimation Error

• Index Error

Two faces of shade glass and mirrors are not parallel.

• Prismatic Error

• Centering Error

• Graduation Error

• Index Error

The index arm is not pivoted at the exact center curvature of the arc.

• Prismatic Error

• Centering Error

• Graduation Error

• Index Error

Occur in the arc, micrometer and vernier of the sextant which is improperly cut or incorrectly calibrated.

• Prismatic Error

• Centering Error

• Graduation Error

• Index Error

The play or looseness in the sextant’s mechanical components that causes inaccuracies.

• Prismatic Error

• Centering Error

• Backlash

• Double Reaction