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Polar alignment is the act of aligning the rotational axis of a telescope's equatorial mount in parallel with the rotational axis of the Earth. There are various ways to achieve this.
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Alignment Methods
The method to use differs depending on if the alignment is taking place in daylight or in night. Furthermore, the method differs if the alignment is done in the Northern Hemisphere or Southern Hemisphere and σ. The purpose of the alignment also must be considered. For example, the demand for accuracy is much more significant in astrophotography than in occasional stargazing.
Daytime alignment
Aim at a Pole Star method
Northern Hemisphere
Sighting on Polaris the North Star is the usual procedure for aligning a telescope mount parallel to the earth's axis. [1]
Southern Hemisphere
σ Octantis the South Star
Drift Alignment
A rough alignment is performed - then refined by pointing at different stars and observing any drift that occurs. The mount is then adjusted according to the direction of the observed drift.
Equipment used in polar alignment
Crosshair Eyepiece
A crosshair eyepiece is an ordinary ocular with the only difference that it has a crosshair for aiming and measurement of the angular distance. This is useful in any type of polar alignment, but specially in drift
Auto guiding systems
Dedicated Polar scope
A small telescope usually with an etched reticle that is inserted into the rotational axis of the mount.
References
- ^ Michael A. Covington (1999). Astrophotography for the amateur. ISBN 9780521627405.
See also
External links
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