How is the geomagnetic prime meridian defined?

[envanyatar]

Hi,
Does anyone know how the geomagnetic prime meridian is defined, particularly relative to the Greenwich meridian?

Thank you.

 

[jedishrfu]

google serch yielded the following book link:

http://books.google.com/books?id=Hr...=onepage&q=geomagnetic prime meridian&f=false

The graphic shows that the geomagnetic prime meridian is a line thru the geomagnetic northpole and the geographic northpole meaning that it may not align with the greenwich meridian.