How to Adjust a Sextant

For centuries, mariners have used sextants to aid in navigation by measuring a celestial object's elevation in respect to the horizon. The angle is used to determine position on a map. One of the most common uses is to calculate the angle of the sun at noon, which is when it is at its highest latitude. It is important to get as precise a measurement as possible, and that requires the ability to make adjustments to the sextant.

• 1

  Adjust the mirrors to make sure you get the most precise measurement by using the adjusting screws. Adjust the mirrors so they are perpendicular with the frame. When the sextant it set to zero, the two mirrors are parallel. This sets the mirrors correctly.

• 2

  Choose a celestial object in the sky and hold the sextant in your right hand. Look through the telescope and line up the object, such as the sun or the moon, with the horizon. This is the most vital step in the process; it creates the basis for the remainder of the adjustments.

• 3

  Pivot the index arm, making sure the sextant is vertical. The object creates an arc with the horizon. When the object is at the the end of the arc, the sextant is vertical. This is where you attain the measurements of degrees and minutes.