Modeling Velocities

[Steve Allen]

On Sat 2018-12-22T13:40:40-0500 Arnold Rots hath writ:
>   which reference frames apply?
> Depends on what the provider of the data used; for modern data one would
> hope ICRS, but historical data could be any FK

In historical data each catalog is its own reference frame,
and the literature of constructing recent catalogs using the
old data shows the painstaking measures needed to remove the
systematic effects present in the original catalogs.

> On the other hand, I suspect that for proper motions with any reasonable
> precision this won't make a bit of difference

That statement would remove volumes of painstaking efforts from the
literature.

--
Steve Allen                    <sla at ucolick.org>              WGS-84 (GPS)
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