[TowerTalk] Declination

[James L. Johnson]

The following paragraph was taken from the USGS web site at:

http://www.usgs.gov/fact-sheets/finding-your-way/finding-your-way.html

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     To use this bearing, you must compensate for magnetic declination.
If the MN arrow on the map magnetic declination diagram is to the right
of the true north line, subtract the MN value.  If the arrow is to the
left of the line, add the value.
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   The USGS is using the term "magnetic declination" to describe the
difference between true north and magnetic north.  Perhaps they are
wrong too?

73,
Jim W6SC
jjohnson@hpl.hp.com


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>From owner-towertalk@contesting.com Thu Nov 12 14:28:51 PST 1998
X-Sender: wa2moe@mail.doitnow.com
Date: Thu, 12 Nov 1998 15:24:31 -0700
To: "Jon, W4ZW" <w4zw@home.com>
>From: Stu Greene <wa2moe@doitnow.com>
Subject: RE: [TowerTalk] Re:Declination 
Cc: towertalk@contesting.com

... snip ...

Jon...you're right...but the theme is compass deviation and  compass
variation all from true north, and the word "declination" has incorrectly
been used in lieu of both deviation ( compass error) and variation ( the
angular difference between magnetic north and true north).  

The problem is to find true north for antenna and rotator alignment
purposes.  A number of solutions have been suggested, eg my own of Polaris
and someone else's great shadow at noon method.  Both will work.  But then
someone wondered what could someone do on a cloudy night , ie no shadows
and no Polaris, with a Boy Scout compass, and my answer is use the damn Boy
Scout compass.  Most beams and quads couldn't care less.

73   Stu

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