Re: We do not know the distance of stars

On Thu, 06 Apr 2006 10:55:36 GMT, NashtOn <nana@xxxxx> wrote in
<Is6Zf.55725$VV4.973743@xxxxxxxxxxxxxxxxxxxxxxx> :

David Ewan Kahana wrote:
NashtOn wrote:

John Wilkins wrote:

mccoy@xxxxxxxxxx wrote:



[snip]


Wilkins, for a star 100s of light years away, that would still be a very
small angle, probably a very minute fraction of 1 degree.



And what, precisely, is it that one should conclude from
your comment?

http://www.rssd.esa.int/Hipparcos/further_more.html#goals

Summary of original scientific goals:

Main Experiment:

Number of stars 100 000
Limiting magnitude V = 12.4 mag
Complete to V = 7.3 - 9.0 mag (*)
Positional accuracy 0.002 arcsec (B=9 mag)
Parallax accuracy 0.002 arcsec (B=9 mag)
Proper motion accuracy 0.002 arcsec per year (B=9 mag)
Systematic errors <0.001 arcsec



THE ACTUAL RESULTS ACHIEVED BY THE MISSION IN ALL CASE SUPERSEDE
THESE EXPECTED PERFORMANCES. THE PROPERTIES OF THE CATALOGUES ARE
SUMMARIZED:

http://www.rssd.esa.int/Hipparcos/pstex/summary_page.pdf

`Median precision of parallaxes (Hp < 9 mag): 0.97 mas.'

(Emphasis is mine.)

David


Actually, I disagree with mccoy on this one. Just pointing out to that
know-it-all Harshman

It was Wilkins.

that the value of the angle would be a fraction of
1 degree if you triangulated from one extreme of the Earth's orbit to
the other.

So what? Did you think that no one was aware of that? And what of the
stars that are closer than "100s of light years"?

.

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