Re: GPS 'GR Correction' Myth.

HW@..(Henri Wilson) wrote in
news:23gam1dbrkerjiib64spevonq5r79a3h1n@xxxxxxx:

> On Sun, 30 Oct 2005 14:26:57 +0000 (UTC), bz
> <bz+sp@xxxxxxxxxxxxxxxxxxxx> wrote:
>
>>HW@..(Henri Wilson) wrote in
>
>>>>>
>>>>
>>>>You do realize that the MOONs orbital excursions would make less than
>>>>0.26% difference in the distance calculations, don't you? Divide
>>>>385000 km * 2 by 2 AU.
>>>
>>> The moon is not heavily involved.
>>> We have a satellite buzzing round the Earth measuring parallax angles.
>>> The measurement will depend on which side of Earth it is because the
>>> Earth might bend the incident light by more than the sun.
>>> Jupiter's position might be relevant too.
>>
>>
>>Henri, if such effects were important, they would have been noticed and
>>noted by now.
>
> No they wouldn't.
>
>>
>>Right now, you sound like me, when I first learned about stray
>>capacitance and inductance and wondered how an audio amplifier could
>>ever work with all the stray capacitance and inductance around. When I
>>learned a bit more about electronics, I understood what had to be
>>worried about and when.
>>
>>The real astronomers have been collecting parallax data for well over
>>100 years and cross checking one thing against another all that time.
>
> It wouldn't show up in cross checking. All reading are out... even the
> reference stars. The error is small for close stars anyway.
>
>
>>Putting the andromeda galaxy where you suggest it should go would be
>>like trying to put the continent of Austrailia onto Long Island, New
>>York.
>>
>>It won't fit! It can't fit. It would be silly to think it could fit.
>
> nonsense.

You mean you actually think that a galaxy that is over 250,000 light years
in diameter could be put 587 LY away from the earth?

You do realize that we would be in the MIDDLE of the thing, don't you?

> Actually, its real parallax is not zero. It is negative. ..but since
> Einsteinaian says that cannot happen, astronomers have found a way
> around it by using reference stars.

Parallax has nothing to do with Einsteinia.

>>Worrying about the influence of Jupiter or even the earth on satellite
>>parallax measurements is like worrying about the dime you dropped out of
>>your pocket last week causing the national debt of the US to double.
>>It ain't sig-nif-i-cant
>
> How would you know? You haven't done the maths.

You do realize that the MOONs orbital excursions would make less than 0.26%
difference in the distance calculations, don't you? Divide 385000 km * 2 by
2 AU.

> A MAS is pretty small
> you know.

If it can move the andromeda galaxy 2.9 million light years, it ain't
small.

Oh, it didn't make that move, you did by claiming that nothing was further
away than 587 LY.

Yeah, I know a mas is small
[quote http://www.answers.com/topic/parsec]
Because of the extremely small scale of parallactic shifts, ground-based
parallax methods provide reliable measurements of stellar distances of no
more than 325 light-years, or about 100 parsecs, corresponding to
parallaxes of no less than 1/100 of 1 arcsecond, or 10 mas (1 mas or
milliarcsecond = 1/1000 arcsecond).

Between 1989 and 1993 the Hipparcos satellite, launched by the European
Space Agency (ESA) in 1989, measured parallaxes for about 100,000 stars,
with a precision of about 0.97 mas, and obtained accurate measurements for
stellar distances of around 1000 pc.
[unquote]

Notice, they don't use parallax to calculate thing further away than 1000
pc or about 3.26 K LY.



--
bz

please pardon my infinite ignorance, the set-of-things-I-do-not-know is an
infinite set.

bz+sp@xxxxxxxxxxxxxxxxxxxx remove ch100-5 to avoid spam trap
.

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