Euler rotations in galactic plane to change to equatorial

[birdhen]

HI there,

I am having problems understanding something.
If I have an axis pointing towards the galactic north pole, and I rotate it using an Euler rotations how can I can I establish the rotation angles needed so that it will be pointing to the equatorial North pole.
I am looking for values alpha and beta where alpha can run from -pi-->pi and beta can run from -pi/2-->pi/2.

Many thanks

 

[phyzguy]

Try this:
http://en.wikipedia.org/wiki/Galactic_coordinate_system
There are also links at this page to a couple of different online conversion tools which will do the conversion for you if you just want the answer.

 

[birdhen]

Thank you for your reply. I am getting confused still. Would the galactic north pole just have l=0 b=90 in galactic coordinates? I am imagining the surface of a sphere, if b=90 is the top point of the sphere, then there can be no l value as the horizontal plane through the sphere would just be a point.

 

[phyzguy]

These types of coordinates systems have a singularity at the poles, so the north galactic pole has coordinates (L=anything, B=90). The same is true on the Earth. If the latitude is 90 degrees, it doesn't matter what the longitude is, you are at the pole.

 

[birdhen]

OK , of course, thanks !