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## Determine geographic North

 To: Determine geographic North k0rc@pclink.com (Robert Chudek) Fri, 25 Oct 1996 21:52:11 +0100
 ```>> I've been waiting for the opportunity to share >>this technique with the world. It looks like the time >>has arrived! ---Big snip here--- 73 de Bob - K0RC At 08:21 PM 10/24/96 -0500, you wrote: >Too bad its all wrong- some time checking would have been >better for us all. There may be some out there that believe >you. ---Big snip here--- > >Bill Aycock --- Persimmon Hill --- Woodville, Alabama, USA >(in the N.E. corner of the State) -- also -- W4BSG -- Grid EM64vr > OK Bill, I sit corrected... [I can't stand and type at the same time :-)] You are correct. I left out one critical part. I've rounded up the final word and submit "Rev B" for the procedure. The following information was plagiarized from: http://cpcug.org/user/jaubert/jsundial.html (all you would ever need to know about sundials, etc... >From their web page: "Finding true north In principle, north can be located by using a magnetic compass and making an appropriate correction. Magnetic north is substantially off from true north -- the exact amount varies by location. But there are better ways. Polaris, the north star, can be used, but this is inconvenient -- you have to wait for a clear night -- and not entirely accurate either. The most accurate way to find a true north south orientation is by using the sun itself to find the direction of a shadow cast by a vertical object when the sun is at its zenith. This is easier than it sounds, and can be done by measuring the length of the shadow cast by the upright before and after noon. Set up a vertical pole (or a use a rope with a weight) to cast a shadow on the ground. If you use a rope you will need to make the reference point somewhere near the top to cast a visible shadow -- like a stick knotted into the rope) The base of the shadow will be the first point for your south- north axis and the reference point or top of the pole will trace the second point. At some time in the morning, mark the spot on the ground where the reference point casts its shadow. Measure the length from the base to the end of the shadow, and using a string of that length, trace out a semi-circle on the ground with the base of the shadow as its center point. As the sun rises higher in the sky, the shadow will first shorten as noon approaches, and then will lengthen. At some in the afternoon it will reach the semi-circle you traced in the morning. Note the spot when it crosses the arc the second time. The midway point between the morning and afternoon points, will be directly north of the base point of vertical object." 73 de Bob - K0RC Recalibrating all his rotors... -- FAQ on WWW: http://www.contesting.com/towertalkfaq.html Submissions: towertalk@contesting.com Administrative requests: towertalk-REQUEST@contesting.com Problems: K7LXC@contesting.com Sponsored by Akorn Access, Inc & KM9P ```
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