[IRCA] 1610 bearings - magnetic declination

["Fred Schroyer" <freditor@xxxxxxxxxx>]

I don't know how everyone is deriving their bearing angles...but if you are
doing it crudely, like I am, with a portable receiver & a hand compass, you
have to adjust for magnetic declination to get the true "map north" bearing.
In my case, here in SW PA, the magnetic declination is 9 deg W.   9 deg can
make a BIG difference over a distance. Declination varies widely with
location; it's easy to find yours online. Whether you add or subtract the
declination from your compass reading depends on where you are. This is a
very signif potential source of error in our readings. And I can never
remember whether to add or subtract it; have to figure it out each time!

Fred Schroyer 
Freelance Science Writer / Editorial Consultant 
955 Sixth Street - Waynesburg, PA 15370 
(40 air mis S of Pittsburgh - 20 air mis N of Morgantown, WV) 
Home 724-627-8844 - Work 304-599-7830 x 1120 
freditor@xxxxxxxxxx 



 
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