Dear colleagues,

first of all I would like to emphasise that the initiation of the 
IERS Combination Pilot Project can be considered as an 
important step towards a rigorous combination and more consistent 
and accurate IERS products. Furthermore, it should be recognised
that the services gained a significant progress regarding the
intra-technique combination, which clearly is a fundamental basis 
for the computation of consistent IERS products. Thus, from our 
point of view, it is important that the IERS CPP should be continued.
But on the other hand, it is very clear that there are a number 
of remaining issues and problems that need to be addressed 
in much more detail (which is also obvious from the latest e-mail 
discussions). The planned IERS Workshop in San Francisco 
would provide the framework to present first results of the weekly 
combinations, to discuss remaining problems and to stimulate 
further activities.

Below some comments of the DGFI combination center are
summarized:

1) According to the need of a multi-years reference solution
for the weekly inter-technique combinations (as mentioned already 
by Jim and Zuheir), we support that the IERS should release a call 
for the submission of weekly/daily input data over the entire time 
span of data for the different techniques as soon as possible. 

2) Despite of remaining deficiencies (e.g. regarding a "new"
multi-year reference solution, local tie problems as mentioned 
already in previous e-mails), the combination groups
should start (or proceed) with the weekly inter-technique 
combination. This is important to study various combination
issues in detail, to identify problems and to enhance the 
combination procedure. Feedback to the services is important, so
that they can optimize the intra-technique combinations. 
DGFI has analysed the available input data regarding various 
issues (e.g. the suitability for a rigorous combination, 
datum constraints, etc.), which will be presented at the planned 
workshop in San Francisco, together with first results of the 
weekly inter-technique combination. 

Best regards,
Detlef
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Dr.-Ing. Detlef Angermann
Deutsches Geodätisches Forschungsinstitut (DGFI)
Marstallplatz 8, 80539 München, Germany
phone: ++49-89-23031217; fax: ++49-89-23031240
E-mail: angerman@dgfi.badw.de
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