Glaramaraman said:I guess this topic will have been debated before
- however, can some one concisely explain to me why...
... on my Memory Map Navigator Software for The Lake District I have a c100m
discrepancy between position:N 54degrees,30 seconds, E 3degrees and the Graticule Intersection marked on
the map.This location is just SSE of the outflow from Grisedale Tarn near Fairfield.
I have yet to take my GPS into the field - but my cursor shows a point
approximately 100m ESE from the Graticule Intersection. as marked.I ask as I was idly thinking that such a spot would be a cool location for a
Geocache - but only if I can determine exactly where to put the box!!glaramaraman
It looks like a datum problem.
When set to degrees, Memory-Map uses the WGS84 datum, whereas I presume
OS maps show the lat / lon using the OSGB36 datum.
I think the difference between these datums is about 100m E/W.
For geocaching, the standard datum is WGS84 (with Deg, Min).
For British Grid, the only correct datum is OSGB36.
--
Craig Wallace
http://craig.neogeo.org.uk
http://www.neogeo.org.uk