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To: <towertalk@contesting.com>
Date: Fri, 13 Nov 1998 15:50:58 -0500
From: esicmail <ESICMAIL@USGS.GOV>
To: designserv@ipass.net
Subject: Re: Magnetic declination vs magnetic variation
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In response to your November 13 message to USGS:
The "Geodetic Glossary" of the NOAA/NOS/National Geodetic Survey defines the
term this way:
[quote]
Declination, magnetic #The angular direction, east or west from the north
branch of the celestial meridian, of magnetic north as determined by the
positive pole of a freely suspended magnetic needle that is not subject to any
transient, artificial disturbance.#
In nautical and aeronautical navigation the term variation is used instead of
declination, and the angle is called variation of compass or magnetic
variation. Except for usage in navigation, magnetic declination is not
synonymous with magnetic variation, which refers to regular or irregular change
with time of magnetic declination, dip, or intensity. [end quote]
Diane Brittle
USGS Earth Science Information Center
"esicmail@usgs.gov"
=============
To: <towertalk@contesting.com>
>Date: Thu, 12 Nov 1998 18:22:39 -0500
>designserv@ipass.net would like information/assistance on the following:
>In your paragraph:
>
>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 arow is to the
>left of the line, add the value.
>
>Is the word "delination" correct? Shouldn't it
>be "variation"
>
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