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[_] Calculating magnetic declination

Martin Moore martinm at it-helps.co.uk
Fri Aug 16 14:09:10 BST 2013

> I'm dying to know what this is going to be used for!

Calculating crosswinds on airport runways for commercial stuff like Airbuses, 747's etc!

Some runways have mag bearings, some true, but the wind is always given as true. Right royal PITA.....


Martin.

-----Original Message-----
From: underscore-bounces at under-score.org.uk [mailto:underscore-bounces at under-score.org.uk] On Behalf Of Mark Chitty
Sent: 16 August 2013 13:19
To: underscore at under-score.org.uk
Subject: Re: [_] Calculating magnetic declination

I'm dying to know what this is going to be used for!

m



On 16 August 2013 13:13, Jeremy Prior <jez at netcraft.com> wrote:

>
> On Fri 16 Aug 2013, at 12:30:51, "Martin Moore" 
> <martinm at it-helps.co.uk>
> wrote:
>
> > Today's Friday Afternoon teaser :
> >
> > I need to calculate magnetic declination (difference between true 
> > and magnetic North) for any lon/lat.
> >
> > There are plenty if sites that do it, but I need either the 
> > algorithm or
> a
> > URL that provides some form of interface for this so I can include 
> > in my
> own
> > stuff.
>
>
> Interesting problem.  It's been a while since I looked at this, so a 
> quick refresher on Wikipedia helped:
>
>     https://en.wikipedia.org/wiki/Magnetic_declination
>
> Basically, the declination not only varies by latitude and longitude, 
> but also varies over time (and the rates aren't constant!).
>
> Depending on the amount of accuracy you require (and the volume of 
> queries), the best solution is probably to use the NOAA's calculator at:
>
>     http://www.ngdc.noaa.gov/geomag-web/#declination
>
> It has a CSV output option which is trivial to parse.
>
> ʝɛʑ
> --
> Jeremy Prior
> jez at netcraft.com
>
>
>
>
>
>
>
> --
> underscore_ list info/archive ->
> http://www.under-score.org.uk/mailman/listinfo/underscore
>



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