Heliocentric and baryocentric corrections.

[theneedtoknow]

I have a bunch of spectral images of a star taken at various points in the Earth's orbit. I have used IRAF to determine the heliocentric corrections necessary. I am trying to get a rough estimate as to the difference between these heliocentric corrections, and what a barycentric correction would be. I can't really think of a way to estimate it. The only thing I can think of would be using some classical mechanics to find the common centre of mass between the Earth and the sun, and then find the velocity of the sun around this centre of mass, and it will be the approximate difference between the 2 kinds of corrections. Is this along the right track?

 

[Ken G]

If IRAF does "helicentric corrections", I can't imagine why they would not actually be barycentric anyway. Also, the difference is very small-- whatever correction you needed to apply to account for the Earth's motion about the barycenter, if for some reason you wanted to express that as a heliocentric correction, the difference in the two corrections would be less than 5%. You know how much of a correction you applied, would you care to refine it by 5% of the correction you did? Also, why would IRAF bother to include a heliocentric correction rather than a barycentric one?