In message , oriel36
writes
Steve Willner wrote:
In article ,
"Robin Whittle" writes:
A more reliable source of information about quasar proper motion
than http://laserstars.org is:

Quasar Apparent Proper Motion Observed by Geodetic VLBI Networks
D. S. MacMillan 30 Sep 2003 The 10th Anniversary of the VLBA
http://arxiv.org/abs/astro-ph/0309826

I don't know that it's "more reliable," but it's certainly more
modern and shows what VLBI can do. If QSOs really are ejected from
nearby galaxies (out to 30 Mpc or so), VLBI ought to detect proper
motion. As you say, there will be some confusion with internal
motions in the QSOs, but those should show no preferential
orientation if the putative "parent galaxy" is really a foreground
object.

Notice also that the proper motion observations are complementary to
the statistical association studies. If the ejection velocity is
low, the QSO stays close to the parent galaxy for a long time, and
there ought to be an obvious concentration of QSOs around galaxies.
(There isn't.) If on the other hand the ejection velocity is high,
proper motions ought to be obvious.


Proper motions of stars are pre-galactic notions besides they contain
elements of the celestial sphere in position descriptions of external
galaxies.

Could someone translate this into standard English?


The only real means,at least presently, to determine the actual
positions of external galaxies to our own and subsequently to each
other relies on using the rotation of the foreground Milky Way stars
and supernova data arriving from individual parent galaxies.

As cepheids can be used to determine distance,grafting in the utility
of supernova data to extract the real position of galaxies to the
stellar foreground would be difficult to the nth degree but it is far
more productive and exciting for it returns astronomical methods back
to its geometrical roots.

VLBI is a non starter given its pedigree as calendrically/celestial
sphere based origins.

And this?

.As stellar circumpolar motion is to
Copernicus,'universal expansion' is to Roemer for within that
observation (it is not an illusion and neither can it be intepreted
directly) are the clues to further investigations that involve grafting
in the stellar foreground stars of the Milky Way and their rotation
against the parent galaxies that contain both supernova and cepheids or
the tools to make sense of large scale structures and motions between
galaxies.