Allow choice of ITRF for very accurate mission needs
As of version 9.1, Orekit assumes the loaded Earth Orientation
Parameters defines
a specific version of ITRF that the users should be aware of. For
example if they
load their EOP from EOP 14 C04 files, they will get ITRF 2014. However,
users
can mix EOP from different files (for example using EOP C04 for yearly
files en
Bulletin A for day to day operations). In this case, the EOP history
will not
define a unique ITRF, but will jump from one ITRF version to the other
depending
on data source.
Sticking to one type of EOP file is not sufficient to get a unique ITRF
as some
files changed their reference. As an example Bulletin A switched to
ITRF-2005 in
February 2007, then to ITRF-2008 in February 2011, and recently to
ITRF-2014 in
March 2018. Bulletin B switched to ITRF-2008 also in February 2011 and
as of
writing (2018-04-03) have not yet switched to ITRF-2014.
For most users, this is not a problem as various ITRF frames are only a
few
millimeters or centimeters away from one other. For very high accuracy
needs,
like geodesy, knowing which ITRF is used is mandatory.
Orekit should allow user to specify the ITRF to use, and should abide by
this
selection regardless of the EOP source used. The existing getITRF
method
without any specification should still remain available for less
demanding
applications.
(from redmine: issue id 412, created on 2018-04-03, closed on 2018-06-04)