Hi, Stu--
You have declination defined in the astronomical sense as is used
with right ascension. This OPTICAL use is for astronomers and
navigators.
But declination is also used in the MAGNETIC field sense and is and
was used to mean the offset between true north and magnetic north
by physicists and surveyors for centuries before aviators defined it
differently! (And astronomers also use declination in the magnetic
sense for true/magnetic offset as well.)
The science community and the surveyors (and surveying is what we
are talking about--not air navigation) has always used declination
to mean what the aviators now call variation.
Too many sources to quote--but look in any physics text, any
astronomy text, any physical geology text or any surveyors text--
everybody agrees except for the pilots! (And, again, we are
talking surveying!)
73 John W0UN
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