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Gary adds:

Look at my September 29th post in the sight reduction tables topic for
more information on sight reduction.

gl

On Nov 22, 11:01 pm, glap...@pacbell.net wrote:
> Gary writes:
>
> No, it accounts for the apparant movement of Polaris due to the
> changing position of the earth's pole.
>  If you look in the Almanac you
> find that the positions of the stars change during the year.
>
> Most of the change of coordinates of  the stars published in the
> almanac
> are not due to the stars' proper motions but are due to a change in
> the
> coordinate system used to define the stars' positions, a coordinate
> system that changes with the earth's movement. The zero point of the
> stellar coordinate system is the vernal equinox. Since the earth is
> precessing and wobbling on its axis this zero point moves along with
> it
> making it appear that the stars have moved. Since the earth completes
> on
> cycle of precession every 26,000 years, the vernal equinox moves eight
> tenths of a minute of arc every year and this accounts for most of the
> changes seen in the stars' coordinates.
>
> On Nov 22, 1:39 am, Isonomia  wrote:
>
> > In other words, A2 accounts for the finite distance of the star! That
> > is to say, the star wobbles with respect to the background galaxies
> > (can't say stars because they are too near!!!)
>
> > It is absolutely mind boggling to think that a handheld instrument
> > like a sextant could possibly be affected by the distance to the
> > stars.
>
> > It completely turns history on its head. I've always been led to
> > believe that astronomers looked at the stars as an end in itself - the
> > great scientists pushing back the frontiers of knowledge  - knowledge
> > for the sake of knowledge's sake!
>
> > In fact, it seems to me that knowledge of the stars and motion of the
> > planets was a necessary but fairly god-forsaken task mainly undertaken
> > as a part of the production of accurate navigation tables.
>
> > Engineers produced the equipment necessary to take the measurements,
> > engineers then took the measurements and then some self-publicist
> > scientist came along took what was already known by the engineers and
> > gave it a grand title of the grand theory of space, etc. and claimed
> > it was entirely his work!
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