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Old 19-04-2009, 06:42 PM
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pmrid (Peter)
Ageing badly.

pmrid is offline
 
Join Date: May 2008
Location: Cloudy, light-polluted Bribie Is.
Posts: 3,760
Well Peter, let's begin with this 'southern hemisphere' correction to the Meade manual. Down here, we need to find true south, not north. There are a few ways to do it some more precise than others.
The compass. These are generally not great, especially the cheap ones. But assuming you have access to a reasonably good one, remember that it points to MAGNETIC north and south. The south you need for astronomy work is different - and since I see you are at Morayfield near Cabooltue, you may work on the figure of 11 degrees for your area. Here's how it works. Use your compass to point out magnetic south. Then turn the compass until it is pointing out 169 degree (i.e. 180 minus 11). That will be your siderial south.
Anotgher way is to find out the solar noon time for your location and at precisely that time, hang a plumb-line from a metre or so above the ground and note carefully where the shadow of the string is on the ground at precisely that time. here's their web site:
http://www.srrb.noaa.gov/highlights/...e/sunrise.html
For example, solar noon at my place near Somerset Dam tomorrow will be at 11.48.59 local time. In the calculator, as a int, you'll need your latitude and longditude. If you can't find them quickly, try using the Weather Bureau's (http://www.bom.gov.au ) site and go to their rainfall map. If you enable the option to show the cursor position, and then move the pointer on the 128km rainfall map over your approximate home position, it'll give you the LAt and Long at least to accuracy to the degrees and minutes. HAving had a quick look, it seems likely that you will be somewhere near 27 degrees and 7 minutes EAST and 152 degrees and 58 minutes EAST. So in the solar calculator, enter these both as negative values. Once again, doing the calculation using those coordinates for tomorrow suggests that your solar noon on Monday the 20th April will be at 11.47 and 12 seconds. That'll certainly be pretty close. When you do the plumb-line, mark the shadow line on the ground and try to do it in a fairly permanent way - paint, pegs, post etc. You can then line that up with some object on a distant horizon - a few miles away preferably. You can then use that to get your scope's polar axis pretty close.
I will describe a third method using a program like Stellarium if you still need it but for now I hope the above 2 methids will get you started.

Peter
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