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[IGSMAIL-6070]: change of IGS Reference Frame Coordinator

IGS Electronic Mail      02 Feb 06:26:07 PST 2010      Message Number 6070

Author: Jim Ray, IGS Analysis Center Coordinator

As announced already by Remi Ferland last week, the Reference Frame (RF)
coordination for the IGS is shifting this week from Remi and his colleagues
at Natural Resources Canada (NRCan, Ottawa) to a new team at the Institut
Geographique National (IGN, St Mande, France).  Products for week 1566 were
the last to be generated at NRCan and week 1567 will be the first for IGN.
A very careful evaluation process has been undertaken over the past months
to ensure that users should see no impact apart from a few minor formatting
changes in the weekly summary reports.

The IGS Reference Frame Coordinator, who also chairs the Reference Frame
Working Group (RFWG) and is a member of the Governing Board, forms the
official combination of Analysis Center (AC) SINEX solutions for station
coordinate, Earth rotation, and other frame-related parameters.  Weekly
submissions of AC solutions, including full variance-covariance information,
are combined using rigorous mathematical methods.  The results are then used
by the Analysis Center Coordinator to form the IGS combined orbits and clock
products in a way that maintains a high level of overall internal consistency.

Since May 1999 (GPS week 999), NRCan has supported Remi as IGS RF Coordinator
and since March 2000 (week 1050), the NRCan SINEX combination has provided
the official frame products for the IGS.  Remi has been assisted in this
important activity by Martin Bourassa and Mike Piraszewski, in particular,
and by others in the Geodetic Survey Division (GSD) at NRCan.

The IGS and the many users of its products owe an enormous debt to NRCan,
Remi, and his GSD colleagues for their generous contributions, which have
consistently maintained the utmost levels of quality and reliability.  Not
only have the IGS combinations been produced regularly every week for more
than a decade, the RF Coordinator tasks include many other functions, such
as preparing periodic reference frame realizations, selecting sets of
reference frame fiducial stations, preparing and submitting IGS frame
solutions for ITRF, maintaining combination software, detecting and reporting
discontinuities in station time series, generating Earth rotation product
files, maintaining files of station residuals and related information,
responding to user requests, and preparing periodic reports.  Most recently,
Remi has recombined reprocessed AC solutions back to 1994 that will be the
basis of a new fully consistent solution set for the IGS.

On a personal note, I must add that it has been a total pleasure to work
with Remi over the years.  He has always been a consummate professional, ever
eager to help others while maintaining infinite patience and diligence.  The
IGS has grown and matured in major ways over the past decade, thanks in very
large part to the efforts of Remi and his colleagues.

Starting this week, the IGN team, which is based in the Service de Geodesie
et Nivellement (Survey Department), is assuming the IGS RF coordination
responsibilities.  Bruno Garayt is the new IGS Reference Frame Coordinator
and is responsible for the routine operations with the help of Anne Duret and
Romain Fages.

The required analysis and developments were made around the CATREF software
by a team headed by Paul Rebischung.  Attention was paid to ensure that the
transition would be as smooth as possible.  However, some changes were made
to the NRCAN combination strategy, mainly concerning the weighting of the AC
solutions, outlier detection, and the alignment of the AC solutions to the
combined frame.

Further scientific developments and refinements in the combination procedure
will be made at the IGN Geodesy Research Laboratory (LAREG) under the
guidance of Zuheir Altamimi, Xavier Collilieux and Laurent Metivier, and in
close collaboration with IGS ACs, ACC, and other teams.  The main objective
is to improve the consistency and accuracy of the IGS products, and in
particular to move toward a more fully consistent and rigorous combination

For any questions, the IGN team can be contacted at: igs-rf @

With the greatest possible gratitude for the stellar service by Remi and
NRCan, and with deepest appreciation to Bruno, Paul, and IGN,


PS. The full list of product files at the Global Data Centers now coming from IGN rather than NRCan is (for wk 1567 and subsequent weeks):

 IGS10P03.res.Z    residuals between each AC & cumulative combined solution
 IGS10P03.snx.Z    cumulative combined solution
 IGS10P03.ssc.Z    set of station coordinates in cumulative combined solution
 igs10P1567.erp.Z  daily Earth rotation parameters for week
 igs10P1567.itr.Z  residuals between each AC & IGS05 for the RF stations
 igs10P1567.res.Z  residuals between each AC & combined weekly solution
 igs10P1567.snx.Z  combined weekly solution
 igs10P1567.ssc.Z  set of station coordinates in combined weekly solution
 igs10P1567.sum.Z  combined weekly solution summary report
 igs00p03.erp.Z    cumulative IGS Earth rotation parameters