Polar alignment: Difference between revisions

Revision as of 12:10, 17 November 2016

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{{Cleanup rewrite|Wikipedia is not a manual|section|date=July 2016}}

In the Northern hemisphere, rough alignment can be done by visually aligning the axis of the telescope mount with [[Polaris]]. In the Southern hemisphere or places where Polaris is not visible, a rough alignment is performed by ensuring the mount is level, adjusting the latitude adjustment pointer to match the observer's [[latitude]], and aligning the axis of the mount with [[true north|true south or north]] by means of a [[magnetic compass]] (after taking the local [[magnetic declination]] into account). This method can sometimes be adequate for general observing through the [[eyepiece]] or for very wide angle [[Astrophotography|astro-imaging]] with a tripod-mounted camera. NewcomersThis method is often used by newcomers to [[amateur astronomy]] equipped with an equatorial mountequatorially-mounted telescope should initially adopt this method.

For astro-imaging through a lens or telescope of significant magnification, a subsequent drift alignment is necessary to refine the rough alignment.

The procedure for rough alignment in the '''Southern Hemisphere''' is as follows:

'''Step 1''' Set up the telescope and mount. Ensure that the mount/tripod is level.

'''Step 2''' Use a [[spirit level]] to ensure it is level.

'''Step 3''' Set the [[latitude]] adjustment pointer of the mount to the latitude of your observing position.

'''Step 4''' Using a [[magnetic compass]], align the mount with [[Magnetic south|Magnetic South]]. Make certain that the metallic mount does not influence the compass' ability to define south/north.

'''Step 5''' Realign the mount by the angular difference between the [[South Magnetic Pole]] and the [[Celestial pole|Celestial Pole]]. This varies greatly worldwide and is entirely dependent on the ___location of the observer.

The procedure for rough alignment in the '''Northern Hemisphere''' is to visually align the telescope mount with [[Polaris]], which is less than one degree away from the North Celestial Pole.

Rough alignment followed by drift alignment is required when astro-imaging through a lens or telescope of significant imaging power.

A slightly better alignment is attained when using a calibrated (e.g. with a spirit level) inclinometer with an accuracy of 0.1 degree and coordinates of a well-known bright object not higher than 30 degrees above the horizon, the current sidereal time - clock time offset and the polar axis is cylindrical (i.e. not tapered, unless you know the tapered angle) and (digital) setting circles: