Dear Markus, Jim, and colleagues,

as it comes out from latest e-mail discussions, there might be some 
different ideas regarding the optimal combination strategy (but anyway 
this is one of the major issues of the CPP, which has to be studied in 
detail). However, I guess, that there are no principle doubts about the 
final goals of the CPP. The excellent expertise of the combination group
regarding all space techniques and combination issues should provide
a very good basis for further progress .....


Comments to e-mail of Markus (14.10.2004)
------------------------------------------------------------

> Proposal for Sessions:
> ---------------------
>
> 1) Combination Pilot Project and CONT’02 ("Weekly" SINEX)
> 2) Long Time Series and their combination (ITRF, IERS2005, ...)
> 3) Handling of Systematic Biases
> 4) Conventions, Modelling, Parameterization
> 5) Local Ties

As mentioned already by Zuheir, the CPP is directly mentioned
only as a part of the proposal, but on the other hand all the other 
subjects are also combination issues, and of course important for the
CPP. Thus, from my point of view, it makes sense to discuss all
these items during the planned workshop in San Francisco.
I also agree with Jim and Zuheir, that the material presented at 
the workshop should not be a dublication of AGU presentations. 

We propose the following DGFI presentations (preliminary titles), which 
do have no or only very small overlaps with AGU presentations:
-   Results of CONT'02 combination studies (Krügel et al.)
-   Analysis and combination of weekly input data (Meisel et al.)
-   Analysis of local tie information and biases (Angermann et al.)
-   Reflections about some necessary additions and changes
     to the conventions, modelling and parameterization (Drewes et al.)


Comments to e-mail of Jim (07.10.2004)
------------------------------------------------------------
> If you feel that I am wrong about this, I do not seen any need to wait
> to discuss the issue face-to-face in San Francisco.  Why not present
> your results now, electronically?  If problems and issues can only be
> discussed in workshop settings, then I fear there is no possibility of
> making progress.  After all, we already discussed all these very same 
> issues in Nice and nothing has been done about them since that time.

I agree! As I have mentioned in my previous e-mail (7.10.2004) we have
started to analyze the weekly CPP input data, and we are preparing a 
summary of such analysis results, which we will distribute to the CPP 
group very soon. Maybe there is a way to compare such results with other 
groups before the meeting?


The urgent need of long-term solutions (as mentioned in varios e-mails):
------------------------------------------------------------------------------------------------------

According to my previous e-mail (7.10.04) we support that there
is an urgent need for longer time series and we will contribute
with reprocessed VLBI and SLR solutions. We are almost ready
to submit these series to the IVS and ILRS.

VLBI: Volker Tesmer has almost finished the generation of session-wise 
SINEX files (datum free normal equations) of about 2500 VLBI sessions 
between 1984 and today including telescope station positions, pole 
coordinates and their first derivatives, dUT1 and LOD as well as constant 
corrections to the nutation angles. We would like to indicate that we intent 
to ask the IVS and its Analysis Coordinator to accept our contribution to the 
IERS CPP next week or so. We will try to deliver files for forthcoming 
sessions in a monthly turnaround. Until now, we were not yet able to solve 
all problems related to a non Calc-Solve VLBI contribution to an intra-VLBI 
combination (e.g. related to an usable apriori value for an offset of a 
nutationangle which can only be a very bad approximation of the nutation 
function during the session, usage of different values for the axis offsets 
etc.). But, nevertheless we hope that a contribution will stimulate a further 
discussion about problems and help to get the things on the way to 
improve ....

SLR: In addition to the routine weekly DGFI submissions (since 2003) within 
the ILRS (which are available at the ILRS data base), Horst Müller has almost 
finished to reprocess the SLR data (back to 1981) and we will submit the 
SINEX files to the ILRS for intra-technique combinations.

Best regards,
Detlef