Subject: [IGSMAIL-1080] The IGS Status in October 1995
From: G. Beutler
Date: Thu, 5 Oct 1995 7:21:56 PDT

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IGS Electronic Mail      Thu Oct  5  7:21:56 PDT 1995      Message Number 1080
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Author: G. Beutler
Subject: The IGS Status in October 1995

Dear colleagues,

This is an attempt to summarize the activities and the developments within
the IGS since the Potsdam meeting (see IGS-message No. 961). The following
topics of the 4th Governing Board Meeting of the IGS shall be briefly
discussed here:

 - the IGS as a FAGS service
 - Highlights of the Central Bureau Report
 - Highlights of the Analysis Center Coordinator Report
 - Densification of the IGS Network
 - Elections into the GB by the End of 1995
 - New Directions within the IGS

The IGS as a FAGS Service
-------------------------
Prof I.I Mueller reported to the Board on the potential inclusion of the
IGS in the Federation of Astronomical and Geophysical Data Analysis
Services (FAGS).  The IGS has submitted the requested application to the
IAG.  The IAG will approve and propose the IGS to FAGS.  The IGS should
formally become part of FAGS within the next year.

Highlights of the Central Bureau Report
---------------------------------------
Zumberge reported on the status of the 1994 IGS Annual Report, a
preliminary edition of which was distributed.  Since then a page proof
edition has been completed, and the distribution of the final edition
should take place very soon.  The GB members were very pleased with
the preliminary version of the report -- a lot of work was invested by the
CB to give the report a nice and uniform format.

A further CB topic dealt with a possible semi-annual IGS newsletter.  The
general consensus was that it was a good idea, and would be perhaps the
only way to reach a number of interested parties who are not connected to
the Internet. The CB will look into the feasibility of it.

Highlights of the Analysis Center Coordinator Report
----------------------------------------------------
Since June 1995 the submission deadline for AC products has been reduced
from 2 weeks to 10 days after the last observation data. It seems that the
data flow is in reasonably good shape and that the Analysis Centers are
successful in automating the daily routine. It also should be mentioned
that the quality of the products was considerably improved over the last
two years. All Centers are capable of producing orbits close to or even
below the 10 cm level (rms per satellite coordinate).

A really important improvement of the Analysis Coordinator's work was the
production of a combined, official IGS pole (in addition to the combined
orbits and clocks).  As we have seen in recent IGS-mails (No.  1068, 1072)
this combined IGS pole was carefully analysed and the result had an
important impact on the definition of the IERS Rapid Subbureau's Bulletin-A
pole (IGSMail No 1072).

Densification of the IGS Network
--------------------------------
The proceedings of the IGS Workshop "Densification of the IERS Terrestrial
Reference Frame through Regional GPS Networks" held in Pasadena in December
1994 was sent out by the Central Bureau in September 1995. If you did not
receive a copy please send an e-mail to the CB.

Many technical details had to be addressed by the Analysis Centers, the
Analysis Center Coordinator, the three candidate Associate Analysis Centers
of Type 2 (AAC-T2) before the Pilot Phase for the densification project
could be announced (IGSMail No. 1010) and before the first report of the
JPL AAC-T2, namely

IGSREPORT No. 2003 dated September 11, starting with the statement

"Coordinate comparisons for GPS week 813 mark the beginning of
 type two analysis activities at JPL.  ...",

could be distributed to the IGS community.  Hopefully analyses of the other
candidate AAC-T2 will soon follow.  We are also looking forward to the
future interaction of the AAC-T2 with the IERS.

It seems that the AAC-T2 activities are quite a challenge. I would not
be amazed to see major modifications to the original comparison/combination
schemes in the near future.

Elections into the GB by the end of 1995
----------------------------------------
The IGS Governing Board consists of 15 members.  Two members are appointed
by the IAG (the official IAG represenative, and either Section II- or CSTG-
president), one is appointed by the IERS, six by the CB, and six members
are elected.  Three of the elected members were assigned four-year terms,
three two-year terms.
The first election of the IGS GB, organized by I.I.  Mueller,
took place in 1993.  Because G. Beutler (elected, four year term) will
fill the position of the second IAG appointed GB member (as new CSTG
president) four new members have to be elected. These elections again will
be organized by I.I. Mueller and will take place within the next two
months.

The appointed members will also be (re-)considered at the next GB meeting
in December 1995.

New directions within the IGS
-----------------------------
Based on the outcome of the Potsdam workshop (IGSMail No. 961) the
following action items were discussed by the GB:

 - Monitoring the Troposphere by the IGS

   There was general consensus that the IGS should encourage station
   operators to support surface met instrumentation. There also was a
   general agreeement that barometer (and the other met equipment) on IGS
   sites should be carefully calibrated in the near future.

   GFZ is currently assuming responsibility for tropospheric comparisons
   among the IGS AC's.

   There is an immediate use for IGS troposphere estimates for
   climatological studies.  If more rapid products should become available
   through the IGS (see below) the same data might be used for weather
   predictions (!).

 - Monitoring the Ionosphere within the IGS

   The IGS will consider a pilot project for the ionosphere. John Dow had a
   3-page proposal for routine determination and exchange of ionosphere
   models.  This document has been distributed to the appropriate persons
   at each of the AC's.

   Ionospheric monitoring was considered as an important issue by the GB.
   Individual AC's are making rapid progress in this field. From this
   point of view a pilot project in the near future would be more than
   justified. Such a project should not interfere with the pilot phase of
   the densification project, on the other hand.

 - Rapid Orbits

   Does the IGS want a rapid orbit product?  There was much discussion on
   this issue, but there was no general consensus even on what exactly is
   meant by the term.  On the other hand it was clear from the AC
   Coordinator's report that the products are getting available more
   rapidly (10 instead of 14 days).  It was very clear, however, that
   "Rapid Orbits" should be available after a much shorter delay (24-48
   hours ?).

   After the Boulder meeting first suggestions were discussed to make data
   for a limited number of IGS stations available to all Analysis Center
   within a few hours. Rapid Orbits will be one of many important topics
   at the next Analysis Center Workshop to be held at the NOAA facilities
   in Silver Spring, Md.

This report is only a short summary of a long meeting in Boulder and of
the IGS events which took place in Summer 1995. Obviously the IGS is still
developing rapidly, new interesting applications show up all the time. The
realization of a service like the IGS in times of a world-wide consensus of
budget-cuts must be considered as a miracle. The IGS Governing Board
gratefully acknowledges all the voluntary contributions to the IGS.

                                                    Gerhard Beutler
                                                    Chair,
                                                    IGS Governing Board

[Mailed From: Gerhard Beutler <[email-masked]>]