[IGSMAIL-5896]: expanded Conventions Chapter 7 posted

[Jim.Ray]

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IGS Electronic Mail      11 Feb 10:22:12 PST 2009      Message Number 5896
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Author: Jim Ray (IERS Conventions Advisory Board)

Today Gerard Petit has posted an expanded version of IERS
Conventions Chaper 7 on displacements of reference points.
Please refer to the website:

http://tai.bipm.org/iers/convupdt/convupdt_c7.html

The main changes are:

* A new section 7.2 "Models for the displacement of reference
points of instruments" has been added.  It contains models
for a reference temperature (provided by J. Boehm), the
thermal expansion of VLBI antennas (provided by A. Nothnagel),
and GNSS antenna phase center offsets and variations
(provided by R. Schmid).

* The subroutine hardisp.f has been updated by D. Agnew
following discovery by R. Dach, C. Urschl, and G. Beutler
and by M. Bos and N. Penna of a sign error in the long-period
tides of the 2006 version of this routine.  (This error is
quite small for most practical applications.)  The number
of harmonics used and the internal precision have also been
increased.

* Numerous typos have been corrected and other stylistic
corrections introduced, following remarks by R. Schmid.


Please refer to the IERS Conventions update website:
http://tai.bipm.org/iers/convupdt/convupdt.html