[IGSMAIL-009] IGS status report

[Gerhard]

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IGS Electronic Mail        5-JUN-1992 10:39:07       Message Number 9
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>From:    Gerhard Beutler
Subject: IGS status report
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IGS Status Report, June 4, 1992
_______________________________

Introductory Remarks :

 - The 1992 IGS Campaign will start in 17 days !

 - In IGS Electronic Mail, Message No 2, the May'92 meeting was
   canceled, but it was also stated that many problems/issues had to
   be addressed before the beginning of the campaign.

 - Ruth Neilan is on a trip to Russia. On May 29 I met her at
   the IfAG in Frankfurt, where we discussed the state of
   preparations of IGS affairs and the next steps to be taken.  Also
   present at this meeting were Tim Springer and (partly) Tom Clark
   from GSFC.

 - Below Tim Springer and I try to summarize the state of IGS affairs
   as we saw it in Frankfurt, and the actions taken since.


(1) April'92 Communications Test
    ____________________________

Peter Morgan, our data flow coordinator, was more or less satisfied by
the April 1992 communications test.  Unfortunately he had some serious
health problems in May.  This is why he did not yet deliver the short
summary concerning the communications test in this electronic mail.
Peter sent me a message that he is recovering and that he now has a
hard time to catch up with all his duties.  Good luck !


(2) Instructions from the Analysis Center Coordinator
    _________________________________________________

Processing centers and associate processing centers are still waiting
for the instructions from the analysis center coordinator.  Clyde Goad
has now prepared all the documents, he promised to mail them this
week.

Hopefully only minor program adaptions will be necessary -- the
essential keywords (earth's gravity field, Rock 4/42 radiation
pressure model, orbit formats) were already given in the IGS
Newsletter No 2.  Some discussion was/is going on concerning the earth
rotation parameters, but it seems that this issue is converging too.


(3) IGS Network Centers
    ___________________

According to theory three network centers should be operational at the
beginning of the campaign.  The communications test has revealed that
CDDIS (at Goddard) and SIO (at San Diego) actually are ready (or very
close to that stage), no tests could be made with the center at IGN,
Paris.

A telephone call with Pascal Willis from IGN showed that this center
will be ready "close to the beginning of the campaign". The European
processing centers (which should get their data for global analyses
from IGN) will get this data from CDDIS (or SIO) until the IGN center
is fully operational.


(4) Regional Centers
    ________________

We are not ready for a general overview over this topic at present.
Here is what we know at present :

The Nordic center is ready.

The IfAG in Frankfurt is close to becoming operational (there still is
a problem with the data rate which hopefully can be solved during this
or the next week).

T. Kato's report is rather optimistic about the situation in his
region.

I would like to encourage regional coordinators to prepare short
status reports to be distributed through IGS Electronic Mail.



(5) Receiver Problems
    _________________

Processing centers suffered some difficulties with data collected by
the Rogue receivers in May (see e.g. Yehuda Bock's message of .. May).
It could not be excluded that some of these problems were correlated
with the Rogue receiver upgrade to Version 7.0 . This upgrade
obviously is now available at most sites and is being installed at
some of them. What experiences were made with Version 7.0 ? It is
absolutely necessary that the IGS community is aware of any receiver
related difficulties. The more efficient the communication, the sooner
problems can be solved by the JPL.

By the way:  positive reactions or comments are appreciated too; we
all should keep in mind that we are involved in a rather complex
scientific experiment with many "firsts". One of the major goals of
this year's test campaign is to get a clear picture of all the
(potential) problems involved in a routine GPS orbit determination
service.

Analysis centers might consider making available on a routine basis
log information (similar to that distributed by Y. Bock) through IGS
electronic mail.


(6) Start of Date Flow for the 1992 IGS Campaign on June 15
    _______________________________________________________

We found it absolutely necessary that the routine data flow is
initiated on June 15, one week before the beginning of the campaign. I
asked Werner Gurtner to organize this together with the "key players"
at JPL, NGS, CDDIS, SIO, and IGN. We will hear more about that next
week.


(7) Naming Conventions for Analysis Center Products
    _______________________________________________

The precise formats for orbits and earth rotation parameters are
defined by the analysis center coordinator. It is the processing
centers responsibility to transfer the results to the Network Data
Centers, where naming conventions have to tell the user (a) who
produced the result (b) for what time interval it is valid.
More about that next week.


(8) Coordinates and Local Ties
    __________________________

This crucial issue is in the responsibility of C.  Boucher/Z.
Altamini.  They promised to come up with a list of coordinates and
local ties (based on their IERS Technical Report, No 10,"the IERS GPS
Terrestrial Reference Frame").  This list should be inspected
carefully by the processing centers.  I am sure that the combined
experience of these centers will lead to a list of reliable ITRF 1992
coordinates.  (We believe e.g.  to have a rahther clear idea of the
corrdinates for the European IGS sites at CODE).


(9)  Contributions from the IERS Central Bureau
     __________________________________________

Mme Feissel from the IERS Central Bureau kindly offered to issue a
special IERS Bulletin with the IGS contributions to the determination
of the earth rotation parameters. The name of the bulletin will be

  "IGS'92 Earth Rotation Bulletin (Number)"

The processing centers will send their ERPs in the format defined by
Najat Essaifi and Clyde Goad directly to the IERS Central Bureau.
Also it will be necessary that those processing centers sending
material to the IERS will briefly explain their specialties of
processing (where we expect that the principal issues are settled by
the analysis center coordinator).

Processing centers should have obtained instructions directly from the
IERS central bureau (please check e-mail addresses).  Associate
processing centers and evaluation centers obtain the same information
through IGS Electronic Mail (please read IGS E-Mail Message No 10).


(10) Post Campaign Meetings
     ______________________

We suggest to attach the IGS Oversight Committee Meeting (post
campaign meeting) to the DOSE meeting at Goddard Space Flight Center
on Thursday/Friday, 15/16 October. Tom Clarke indicated that GSFC
might be inclined to host such a meeting.

We will ask Prof.  Ch.  Reigber whether it would be possible to
reserve a time slot of about 2-3 hours at the Symposium on Geodesy and
Physics of the Earth" in Potsdam ( 5-10 October), where we would
mainly expect reports from IGS analysis centers, but also
contributions from the VLBI/SLR community.  We will not organize a
formal oversight committee meeting at this symposium.


Concluding Remarks :

 - If you think that the IGS time schedule is tight right now -- you
   are right.

 - If you think that the situation would have been different half an
   year later -- you are wrong.

                                                Kind regards

                                                Gerhard Beutler
                                                Tim Springer