Pioneer Anomaly discussion continued

Note: this is a continuation of the thread
http://groups.google.co.uk/group/sci.astro/browse_frm/thread/87fb34db20b1af7f


On 5 Mar, 17:20, Craig Markwardt
<craigm...@xxxxxxxxxxxxxxxxxxxxxxxxxx> wrote:

Since the analysis (and the anomaly) involve *neither* averaging *nor*
Fourier transformation, your speculations are still irrelevant. In
fact, a diurnal Doppler error signal due to incorrect station
positions would been readily visible in the residuals, and could have
been corrected by adjusting the station positions (along with any
corresponding biases, if any). No reasonable adjustment of the
station positions could resolve the anomaly (ref. Anderson et al.;
Markwardt 2002).

What I said was that *if* a Fourier transform is applied to the data,
then it would not only show an annual and diurnal residual (which *is*
present according to Anderson et al. (see page 40-42)) but also a
constant residual (i.e. the 'Pioneer anomaly'). Both Anderson et al.
and you arbitrarily ignore the periodic variations (in fact, you
appear to have filtered out the diurnal variations altogether) but
only consider the constant residual as relevant.

Regarding the station positions: you are writing in your paper that
treating these as free fit parameters would converge towards the
'correct' positions to within a few meters. Now this is by no means
sufficient. A change of the radial distance of the station from the
earth's center by just about 10 cm would fully absorb the Pioneer
anomaly (and presumably also the diurnal residuals).


But anyway, whatever your earth rotation model is, if you would change
the parameters such that it corresponds to a reduction of the
rotational acceleration of the observing station by about 5*10^-8 cm/
sec^2, then the anomaly must disappear.

This claim continues to be erroneous. First, earth orientation
parameters are nailed down by huge numbers of observations, so they
shouldn't be "changed" without invalidating all of those observations.
Second, any diddling of these numbers would produce distinct diurnal
Doppler signatures, which would *not* reflect a constant acceleration.

As I mentioned already, the parameters only need to changed within the
nominal errors as stated by the IERS (see http://hpiers.obspm.fr/eop-pc/models/constants.html
).


It *has* been caught in form of the Pioneer anomaly, and it is also
confirmed by the IERS data (seehttp://maia.usno.navy.mil/lod.gif)
where a constant offset of about 1 ms is apparent for the length of a
day (apart from fluctuations of a similar magnitude).

The plot you indicated is irrelevant. That plot shows the *measured
excess* of the length of day beyond the standard length. In other
words this is *not* an "unmodeled drift" since it is measured.

Perhaps you are arguing under the assumption that a standard
fixed-length day is used in the analysis. That assumption would be
false, as I have pointed out several times. In fact, the
instantaneous length of day, rotation speed/angles, etc. are used.
The very measurements you indicated, are used in the analysis.

For the present purpose, the 1ms/day drift *is* an unmodelled drift.
It appears to be essentially the difference between the UT1 and UTC
time scales, and as you may be aware, this is only corrected
occasionally (every 1-2 years) by inserting a leap second (see
http://en.wikipedia.org/wiki/Coordinated_Universal_Time ). So any data
that are not averaged over many years should show this drift, as the
latter is in fact continuous, and the insertion of the leap second is
thus not a proper modelling of the earth's rotation.

Thomas

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