I'm wondering if the data in star catalogues are heliocentric equatorial coordinates or geocentric equatorial coordinates. Also given the distance between stars compared to the distance between the sun and the earth, would this be a big deal to mix up the two?


  • $\begingroup$ I'm pretty sure they are barycentric equatorial coordinates, since that's how ICRF 2000 is defined. Since parallax is sometimes used to determine stellar distance, NOMAD would not treat the Earth as a fixed point (ie, the data is not geocentric). $\endgroup$ – user21 Dec 29 '14 at 22:22
  • $\begingroup$ @barrycarter Please convert to an answer. $\endgroup$ – called2voyage Feb 21 '18 at 16:48

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