Re: precession of mercury

Dr. Henri Wilson wrote:
On Sat, 20 Dec 2008 21:16:17 +0100, "Paul B. Andersen"
<paul.b.andersen@xxxxxxxxxxxxxxx> wrote:

Dr. Henri Wilson wrote:
On Fri, 19 Dec 2008 14:12:59 +0100, "Paul B. Andersen"
<paul.b.andersen@xxxxxxxxxxxxxxxx> wrote:

Paul B. Andersen wrote:
If the stellar aberration weren't _exactly_ the same for
all the objects in a region, then the realative positions
of the objects would change, which would be detected by Hipparcos.
As Jerry has explained, the apparent relative position between
the stars _do_ change due to parallax, it is exactly what Hipparcos
was designed to measure.

But note that the objects I am referring to above are galaxies
and quasars, where the the parallax is negligible.

This should be clear from my posting.
<<
Hipparcos was able to measure the relative positions of the stars
with a precision of few mas. It also measured the positions of
quasars and galaxies. They don't move around relative to other stars.
What the hell do you mean by "They don't move around relative to other stars."?
I mean that quasars and galaxies don't move around relative to other stars.

Since I now have posted the following quite a number of times,
and you _still_ ask questions like this, you _must_ be an idiot.
(It might possibly help to learn what stellar aberration is, though.)

If z = 1, then according to the BaTh the speed of light is c/2.

The major axis in the stellar aberration ellipse should then
be 4v/c, which is 82"; twice of what is observed.
And note well, if the stellar aberration for a quasar/galaxy
were different from stars, the quasar/galaxy would appear to move
around _relative to the other stars_!

Hipparcos was able to measure the relative positions of the stars
with a precision of few mas. It also measured the positions of
quasars and galaxies. They don't move around relative to other stars.
(Look it up if you don't believe it. The Hipparcos catalogue is
available on the net.)

The aberration of Quasars and galaxies is _exactly_ like other stars,
within few mas.

Which means that the light from moving sources reach little planet
Earth at at a speed extremely close to c relative to the Earth.

No way out, Henri.
Stellar aberration falsifies the emission theory.

:) You don't know what you are talking about.
Because Hipparcos orbits in the ecliptic plane and does not spin around a
tilted axis like the Earth, it is insensitive to stellar aberration altogether.

Henri, your ignorance of what stellar aberration is, is long since
thoroughly documented, you don't have to repeat it over and over ad nauseum!

Why don't you learn what it is in stead of making
a fool of yourself over and over again?

> It might detect a very small diurnal aberration that is easy to correct out.

Indeed a satellite in geostationary orbit will experience a diurnal
component to stellar aberration.
If you had known what stellar aberration is, you would also
have known that the semi-major axis in this ellipse is u/c where
u ~= 3km/s, u/c = 1E-5 rad = 2".
It is but a small perturbation of the ten times bigger ellipse.
The stellar aberration ellipse will have 365 small 'wave periods'
along it circumference.

However, since this aberration changes much faster than
the annual aberration, it has indeed to be compensated for,
since it will change significantly during an exposure time.

This is a very important compensation in the HST, because it is
in low orbit so the aberration due to it's movement around the Earth
is (more than) twice as big in amplitude, and change very fast,
and the exposure times are often very long. So the telescope
has to swing back and forth with an amplitude of ~7" during 96 minutes.
This is achieved by a feedback control system steering reaction wheels.
The HST is locked on the target with a precision of 0.01".

However, since the minor-axis in the aberration ellipse depend on
the angle from the orbital plane, the aberration of the stars
within the field will be (slightly) different. This is a problem
since all the stars can't be kept at the same pixel all the time.
A primary target is chosen, and an error of a couple of pixels
has to be accepted for other stars far out in the field.

I will guess a similar technique was used in Hipparcos.
But maybe not.
Does Jerry know?

--
Paul

http://home.c2i.net/pb_andersen/
.

Relevant Pages

  • Re: precession of mercury
    ... tilted axis like the Earth, it is insensitive to stellar aberration altogether. ... since all the stars can't be kept at the same pixel all the time. ... I will guess a similar technique was used in Hipparcos. ...
    (sci.physics.relativity)
  • Re: precession of mercury
    ... which would be detected by Hipparcos. ... and quasars, where the the parallax is negligible. ... Hipparcos was able to measure the relative positions of the stars ... The major axis in the stellar aberration ellipse should then ...
    (sci.physics.relativity)
  • Re: precession of mercury
    ... tilted axis like the Earth, it is insensitive to stellar aberration altogether. ... since all the stars can't be kept at the same pixel all the time. ... I will guess a similar technique was used in Hipparcos. ...
    (sci.physics.relativity)
  • Re: precession of mercury
    ... Dr. Henri Wilson wrote: ... What about quasars, Henri? ... but the aberration is exactly the same as stars, ... The major axis in the stellar aberration ellipse should then ...
    (sci.physics.relativity)
  • Re: precession of mercury
    ... it is insensitive to stellar aberration altogether. ... Indeed a satellite in geostationary orbit will experience a diurnal ... since all the stars can't be kept at the same pixel all the time. ... I will guess a similar technique was used in Hipparcos. ...
    (sci.physics.relativity)
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