Il giorno martedì 21 agosto 2018 19:27:44 UTC+2, Steve Willner ha scritto:
In article ,
writes:
... perhaps nobody understood what i said untill now

Yes, your writing is very hard to understand.

.. a minimal question =
: are the negative parallaxes existing ? how is it possible ?

That has been answered many times before. If the parallax is small,
measurement errors can produce negative values. In essence one is
measuring a _difference_ in stellar positions. If the star doesn't
move, the position change one measures can equally well be either
positive or negative. What the measurement actually gives, knowing
the uncertainties, is a lower limit on distance.

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Steve Willner Phone 617-495-7123
Cambridge, MA 02138 USA

... this converation is continuing 'google group sci relativity'