The relativity of the sky that we see...

[old...@yahoo.it]

(..now probabely our Einstein is looking to another side .. and so i can speak with you sincerly..)
...we see the sky.. with stars and galaxies ... there ..so far and bright ... moment ! ... there , but not much there ... because the negative parallaxes are the 49%...
: a negative parallax is an inexisting thing .. : if you look for an object and you move to the right side you begin to form a positive angle from your starting position and the last position ...but the object can move ( at 100 times the light 'speed ?) or something in the travel'path can deviate the light .. so the angle that you imagined to measure positive , began negative ... : you move to the right but the observed object is like you moved to the link side ! ..all can happen , but the logics must exists ...
: if you look for a near star , untill 100 yers light , the parallaxes are almost all positive ; after 500 y.l. we have many negative-ones untill a percentege of 49%... the dwarf stars are observable untill 200-300 y.l. .. and its seem to have only the 10% of deviation !
So the positive and negative parallaxes have the same probability to exist for not near stars and all it seems deviated ... and almost nothing is where we look , with all the consequence of the case .. the case that they seem to not want that it is so ....
Untill the year 2000 the negative parallaxes are not suspected ...then the HST'datas came ..and they don't want it is true (?), because that concerns too nearly from the dark matter to the universe ' age (1000 times older ?)... and ..and .. the CDS Strasbourg edited about that three catalogues : with all negative parallaxes (49)%! , with 20% neg.! and a reduced and almost normal (?) body !... 15 years ago i asked them :'Why so many negative-ones?'.. :'Hee, hee ..some error..and some intermediate body ..' .. good luck in the hunt !

[Steve Willner]

In article <8db3fb57-cf96-4fd8...@googlegroups.com>,

old...@yahoo.it writes:
> So the positive and negative parallaxes have the same probability

> to exis= t for not near stars

If your measurement uncertainty is much larger than the true value of
the quantity being measured, half the time the measured value will be
negative. This is often useful in astronomy: the negative values
tell you about the noise properties of your measurement. That's why
the actual negative values are published rather than replaced by a
non-quantitative "not detected."

--
Help keep our newsgroup healthy; please don't feed the trolls.
Steve Willner Phone 617-495-7123 swil...@cfa.harvard.edu
Cambridge, MA 02138 USA

[Mike Dworetsky]

Steve Willner wrote:
> In article <8db3fb57-cf96-4fd8...@googlegroups.com>,
> old...@yahoo.it writes:
>> So the positive and negative parallaxes have the same probability
>> to exis= t for not near stars
>
> If your measurement uncertainty is much larger than the true value of
> the quantity being measured, half the time the measured value will be
> negative. This is often useful in astronomy: the negative values
> tell you about the noise properties of your measurement. That's why
> the actual negative values are published rather than replaced by a
> non-quantitative "not detected."

Now that Hipparcos and Gaia are replacing old-fashioned measurements with
large refractors, it is slightly less an issue, but still very important.

A few decades ago, a colleague (the late Tom Lutz) was investigating bias
effects in parallax measurements, and came across a rubber stamp being used
at one observatory that said something like "parallax less than 0.040
arcsec, do not measure this plate". Thus a bias was introduced by ignoring
small or negative parallaxes, and the entire absolute magnitude scale was
skewed. Probably this was not the only such place with a bias against small
measured values.

--
Mike Dworetsky

(Remove pants sp*mbl*ck to reply)

[old...@yahoo.it]

Il giorno martedì 25 ottobre 2016 20:39:59 UTC+2, Steve Willner ha scritto:
> In article <8db3fb57-cf96-4fd8...@googlegroups.com>,
> old...@yahoo.it writes:
> > So the positive and negative parallaxes have the same probability
> > to exis= t for not near stars
>
> If your measurement uncertainty is much larger than the true value of
> the quantity being measured, half the time the measured value will be
> negative. This is often useful in astronomy: the negative values
> tell you about the noise properties of your measurement. That's why
> the actual negative values are published rather than replaced by a
> non-quantitative "not detected."

.. you touched the hearth of problem : the uncertainty of measurement ..
1) first i asked to CDS-Strasbourg and they gave e-mail of the experts (?) and they : ..some possible errors ...some intermediate bodies ..(No words about uncertainty ! ..and 'error' had the smell of hiding the problem ..)
2) the uncertainties -like you say- are possible but in the last numbers - not in all number and in the + or - sign - .. and its are superable easily with more measurements ...while i could see measures with 5 significant numbers repeited at the distance of mounths..

3) later i could show to you how the negative pallaxes are easier and wider if the star has an higther temperature ( higther frequency of light ) , showing that the gravitational lens are unable to explicate phenomenas -- better rephrational lens : you can read in the topic of 'sci. relativity' named '' gravitational or rephrational lens?'' or the case (C) in the topic '' The misterious case of desappeared galaxies'' --
4) if we are speaking of rephractional deviations , the negative parallaxes are showing that the dark matter is already there and the galaxy ' escape and CBR can find a simple explications ...