On 11.06.2013 00:44, Koobee Wublee wrote:
On Jun 10, 11:40 am, "Paul B. Andersen" wrote:

This is interesting, because the question is what the rate of
the precession of the equinoxes were at the time the measurements
were done. If we use 1850 as the middle year, the equation from:
http://syrte.obspm.fr/iau2006/aa03_412_P03.pdf
p = 5028".796195 + 2".2108696t + ..
yields: p = 5025".48 per century at J1850, which is pretty
close to the number used by Clemence for the same year!

Has Paul really read that paper? Koobee Wublee suspects not. Paul
just made up bull****. According to this paper, the amount of
precession measured in seconds can be calculated according to the
following formula. shrug

** 5,208”79695 t – 1”11113 t^2 – 0”000006 t^3

Where

** t = (days – 2,000 Jan 1 noon) / 36525

Thus, on that day of January 1, 2,000, a tare (setting to null) on the
precession angle is performed. A hundred years from now, you can add
1”1 to the rate which means the precession is getting worse (period
getting longer). There is no qualification for you to extrapolate
that backwards.

Did someone mention bull****? :-)

According to this paper:
http://syrte.obspm.fr/iau2006/aa03_412_P03.pdf

The _accumulated_ precession, that is the angle of the equinoxes
with the angle at J2000 as the reference is:

p_A = 5028".796195 t + 1".1054348 t^2 + 0".00007964 t^3 + .. (up to t^5)

Where t is in Julian centuries since J2000.

This is a phase.

But the _chance_ of the angle of precession per century is:

p = dp_A/dt = 5028".796195 + 2".2108696 t + 0".0001302 t^2 + ..

This is an angular frequency.

The rate of change of the precession of the equinoxes
at J2000 is 5028".796195 per century, or 50".28796195 per year.
So the period of the precession is at J2000: (T = 2pi/w)
(360*60*60)"/(50".28796195 per year) ~= 25772 years.

This is the period you claimed to be the "correct one".
It is - at J2000.

But no dramatic change happened in the solar system
at J2000, so there is no reason to claim that the equation
above can't be used for the centuries prior to J2000.

So the 'most modern' estimate of the rate of precession of
the equinoxes at J1850 is:
p(1850) = 5028".796195 - 2".2108696 1.5 ~= 5025".48 per century
(second order terms and higher ignored)

So to sum it up:

The observed precession of the perihelion of Mercury
is found in Clemence's paper:
http://www.gethome.no/paulba/pdf/Clemence.pdf

Observed precession of the perihelion of Mercury: 5599.74+/-0.5
Modern estimate of precession of equinoxes at J1850: 5025.48
Precession of the perihelion relative to 'stationary space': 574.26+/-0.5
The tug from other planets is 531.63 ± 0.69
Anomaly = 42.63 ± ~1.2

Conclusion:
GR's prediction for the 'anomaly': 42.98 ± 0.04
is well inside the error bar.

--
Paul

http://www.gethome.no/paulba/