Sextant Errors:
- Perpendicularity Error
- Side Error
- Index Error
- Collimation Error
What is Error of Perpendicularity? What is 1st adjustment screw and where is it fitted?
- It is caused if the index mirror is not perpendicular to the plane of the instrument.
- 1st adjustment screw is used to adjust index mirror to perpendicular position. It is on the centre line (top, middle or bottom) of index mirror.
What is Side Error? What is 2nd adjustment screw and where is it fitted?
- It is caused if the horizon mirror is not perpendicular to the plane of the instrument.
- 2nd adjustment screw is used to adjust horizon mirror to perpendicular position. It is on the centre line top of horizon mirror.
What is Index Error? What is 3nd adjustment screw and where is it fitted?
- It is caused by the horizon mirror not parallel to the index mirror when index arm is at zero.
- 3rd adjustment screw is used to adjust horizon mirror parallel to index mirror when index arm is at zero. It is on the edge of horizon mirror.
What is Collimation Error Of Sextant ?
- It is caused by axis of telescope spectacles is not parallel to the plane of instrument.
- Special collimating telescope fitted with spider threads (cross wires) in the eye piece used to adjust collimation error.
