Celestial North v Magnetic North ?

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Celestial North v Magnetic North ?

Post by gfletcher »

Hi Guys

Is there a formula for determining the difference in degrees and minutes between Celestial North and Magnetic North dependant upon where you live ?

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David Frydman
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Post by David Frydman »

The magnetic pole wanders continually. It is time dependent, although these differences may not be significant, depending what accuracy you need.
I think the runway at Heathrow chenged from 28 to 27, i.e. 280 degrees to 270.
Recently Stansted changed I think from from 05 to 04.
They did not physically move, the magnetic deviation changed, so the compass headings changed just slipping over the mid point of 5 degrees out of ten.
You can find the magnetic deviation approx from web sites for your town but you must at least put in 2011 as the year.
Regards, David
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Post by LeoLion »

This site should 'cut the mustard' for what you want http://www.threelittlemaids.co.uk/magdec/index1.html . The OSmaps show the variation on them too.
I'm old fashioned enough to regard my GPS as an auxiliary device and not a mainstay for hill walking survival :D
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Post by Cliff »

Dear LeoLion
Thanks for the pointer to that interesting site.
I must admit I was embarassed not very long ago when someone asked me the necessary adjustment for "real" north relative to "magnetic north". I quoted the first thing that came into my head which had been applicable many years before when I was a keen hillgoer myself.
I must admit to even worse embarassment on two occasions long ago when I was on the hills in bad weather - I actually insisted our compass was pointing in the wrong direction. Luckily I was out-voted by my companions and I wasn't quite daft enough to wander off relying on my own assessment.
GPS didn't exist in my hill-going days. I don't like my wifes "satnav" it seems to take longer to set up than time it might save driving.
Arguably though having GPS when I made my above compass fau-pas might have comfirmed to my satisfaction our compass was right and I was up the creek.
So like you I'll give GPS the nod as a useful but not essential auxillary.
Best wishes from Cliff
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