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Guide to Marine Sextant, image - Coggle Diagram

- - - - It is used in celestial navigation to find out the latitude and longitude.
      - used by mariners to measure the angle between the horizon and a visible object
      - ¿What does it measure?
        
        Vertical Sextant Angle (VSA)
        
        Horizontal Sextant Angle (HSA)
        
        Altitudes
- - - - Columbus used it extensively on his voyages to the New World
      - Recordings
        
        Latitudes Marking
        
        Visited places
        
        Polaris in degrees at ports
        
        Altura or altitude Calculation
        
        Using Quadrant to take the altitude of the Sun when it came to its highest altitude at local noon and then make a correction for the position of the sun north or south of the equator per the date.
- - - - caused when the index glass is not perpendicular to the plane of the instrument.
    - - This is caused by the horizon glass not being perpendicular to the plane of the instrument.
    - - This is caused if the index mirror and the horizon glass are not exactly parallel to each other when the index is set at 0 degrees 0.0′.
        
        methods of obtaining the index error of a sextant
        
        By observing the horizon
        
        By observing the star or planet
        
        By observing the Sun
    - - This is due to the axis of the telescope not being parallel to the plane of the instrument.
  - - - Due to the inaccurate graduation of the main scale on the arc or of the micrometre/vernier
    - - The shades should be so mounted that their glass surfaces are normal to the rays of light passing through them
    - - Caused if the pivot of the index bar is not situated at the geometric centre of the arc.
    - - Caused by prismatic errors of the mirrors or aberrations in the telescope lens
    - - This causes a backlash, leading to inconsistent errors.