j2000 coordinate_system

I think I neved used it!. For the name they looks to me Equatorial Coordinates defined at 2000, i.e. By the precession movement of the earth, the equatorial coordinates of the stars are changing. If you take a look to a spezialized book of stars you will find their equatorial coordinates defined for 1950, 2000, etc. Does that help?

Raul

Raul,

Ok. I dont know much about astronomy. Is galactic_grid and j2000 coordinate_system are related to each other ????

Ummmmh!

- Galactic_grid is a grid, is the representation of the Galactic Coordinate System . We have other 2 more grid: horizontal and equatorial grid.

- Horizontal grid is about ANY location and it uses altitud and azimuth coordinantes (for example the Sun has different altitud just now inn your location and mine).

- Equatorial_grid is about the Celestial Equator line. So any stars (or planet) has the same equatorial coordinates in any location of the earth. (sun, planets and any Solar system body change their coordinates becasuse they are moving trhough the sky). By the preccesion movement of the earth, ALL the stars (galxies, nebulas....) are changing their equatorial coordinates litle by litle, for that in Astronomy we use Equatorial corrdinates refered to a mark of time 1950 or 2000 (j2000).

- Galactic_grid is about the position of the bodies refered to the Galactic plane. It is more usual for describing for example how is the Milky Way.

If you explain what you want to do maybe we can help you more.

Raul