Thread: Polar Alignment
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Old 12-07-2013, 09:01 PM
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pmrid (Peter)
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Join Date: May 2008
Location: Cloudy, light-polluted Bribie Is.
Posts: 3,760
Before you drift align, it helps to be "in the ballpark".

Because I don't know your level of experience, I will run the risk of teaching granny to suck eggs (I hope that's a universal expression).

To get a south point, you need either:
(a) a decent compass and the figure for your local magnetic deviation - remember it is not magnetic south you want but celestial south. Here, the figure is about 11 degrees and my celestial south is at about 169 degrees magnetic; or
(b) a piece of string with a weight on the bottom and a watch. Find the local time for solar noon and by using a plumb-bob, mark the shadow of the string-line at that precise time and it will give you a perfect south line. Put some marks on the ends of the line and use it to position your mount. I have found that if I stand back with a straight piece of timber or metal, and by holding one end of it over one end of the line while looking down the length of the rod or ruler or whatever, you can quickly see whether your mount's RA axis is on the same line. If it isn't, use the azimuth adjustment to get it there.

Then, you need a spirit level. Your mount should be reasonably level - perfection is not necessary.

Then you need to know you local latitude and have so sort of inclimometer or other means of making sure your RA axis is set at that level. A piece of cardboard cut to the angle will do and you can use your spirit level again.

Once you have done those things, you should be fairly close. Drift aligning from there should be reasonably fast and reliable.

If you need any help with drift aligning, just ask - plenty of people here will offer advice - most of it good.

Peter
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