2. Summary of the answers
and comments to the Newsletter 2
Definition
-
it is necessary to abandon the IAU 1980 conceptual definition which
specifies that ``this pole has no nearly-diurnal motion...",
-
the reference pole has not to be defined by its realization but by
a clear concept not dependent on further improvements in the model,
-
this pole must be realizable by a model as accurately as possible,
-
the change from the CEP to the new definition has to be as less as
possible in its practical realization,
-
a change of name could be considered as the ``Celestial Reference Pole"
(CRP), or the ``Celestial Intermediate Pole" (CIP),
-
the deterministic approach seems to be preferable, as it appears to
be more easily realizable and A3 is the preferred option,
A much debated question is to include or not the diurnal and semi-diurnal
terms of nutation in the CRS. Perhaps it should be necessary to define
a ``Mean CRP" (MCRP) including only the long periodic part of the
motion both in the TRS and the CRS, and then a ``true CRP" as obtained
by adding the high frequency components to the polar motion of the MCRP.
Realization
-
the pole of reference must no more be realized by the IAU 1980 theory
of nutation,
-
the reference pole must not be defined by a model, but must be realizable
by a model as accurately as possible,
-
precession and nutation must be specified by a conventional model,
including or not the high frequency nutations according to the chosen option
for the conceptual definition,
-
the preferred option for realizing the pole is to extract the high
frequency signal (or corrections to an empirical model for this signal)
from the pole coordinates only (C3),
A much debated question is if the high frequency signal in polar motion
must be estimated together with the long periodic motion in the software
for processing the data or must rather be estimated in a second step from
the currently estimated coordinates of the pole.
