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Re: starship-design: Massively Distributed Computing for SETI
Ben Franchuk writes:
> "L. Parker" wrote:
> > It all depends upon which star you choose, some do display quite a bit of
> > proper motion relative to us. However, you are correct, that most do not, IF
> > you average for the effects of our own planetary orbit
> Does anybody know of any programs that do that, showing positions of the stars
> in the past or the future from any point in space?
Any good astronomical ephemeris program should do that, for the stars
whose proper motions are known. There's a very nice program called
XEphem that runs on UNIX systems.
Also, Lee, proper motion is defined as a star's average angular motion
against the sky over a multi-year period, not any instaneous measurement
of relative velocity. In general the proper motion of a star has to be
determined by observations of a star's movement over long periods,
subtracting out various things like relativistic aberration, parallax,
and other short-term variations in the star's apparent position.