Subject: [IGEXMail-0519] IGEX-98 Workshop Summary and Future Plans
From: "Slater, James A." <[email-masked]>
Date: 27 Oct 1999 17:33:46

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IGEX Electronic Mail    27-Oct-1999 17:33:46                   Message No 0519
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Author: "Slater, James A." <[email-masked]>
Subject: IGEX-98 Workshop Summary and Future Plans

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IGEX-98 WORKSHOP

The IGEX-98 Workshop held on 13-14 September in Nashville, Tennessee was a
great success.  Approximately 80 people attended.  I want to thank all the
members of the Steering Committee and the Workshop Organizing Committee for
their efforts in planning and coordinating the campaign, and the workshop
that followed.  Carey Noll was invaluable as the Co-chair of the Workshop as
was Pascal Willis, Chair of the Steering Committee.  The other members of
the committees were Gerhard Beutler, Werner Gurtner, Guenter Hein,
Wlodzimierz Lewandowski, Pratap Misra, Ruth Neilan, and Robert Weber.   Thus
far, only two-thirds of the papers have been submitted for publication in
the workshop proceedings.  If you are the author of one of those papers that
has not been submitted yet, please submit it as soon as possible to the IGS
Central Bureau web site <http://igscb.jpl.nasa.gov/submissions/index.html>.

IGEX-98 Highlights

The accomplishments of the experiment surpassed our expectations.  Each
individual and group that participated contributed directly to this success.

>  A global network of over 60 GLONASS tracking stations and 30 Satellite
Laser Ranging observatories in 25 countries participated in the campaign.  
>  Six months of continuous data were collected by these stations and
archived at NASA Goddard Space Flight Center (GSFC) and the Institut
Geographique National (IGN). This data set is a valuable asset that is
available for use by anyone.  
>  Precise orbits were computed, from both the SLR and GLONASS receiver
data, by 11 different groups, with resulting accuracies of 20-50 cm.  A
combined orbit was computed at the University of Technology, Vienna from the
individual solutions provided on a regular basis by a subset of these
groups.  The precise orbits are also archived at NASA GSFC and IGN.  
>  Three commercial manufacturers and one university produced dual-frequency
GLONASS receivers, which were operated and given their most thorough testing
and evaluation as a result of IGEX.  
>  A number of different software packages (e.g., BAHN, Bernese, GIPSY) that
were designed for GPS observations can now process GLONASS data and compute
GLONASS orbits routinely.  
>  The RINEX and SP3 data exchange formats have been expanded to included
GLONASS data.  
>  Datum transformations relating PZ-90 to WGS 84 and ITRF reference frames
were derived by several groups for the first time with a global distribution
of data.  
>  By utilizing the precise orbits, the ability to perform inter-continental
time transfer was improved significantly.  

A summary of IGEX-98 and some of the results presented at the workshop are
in a paper that was given at the Institute of Navigation GPS-99 conference
that followed the IGEX-98 Workshop in Nashville.  A copy of this paper,
titled "The International GLONASS Experiment (IGEX-98): Organization,
Preliminary Results and Future Plans", can be found in the IGEX web site
under www.ion.org/workgroup.html <http://www.ion.org/workgroup.html>.  A
list of workshop participants is also available at that web site. 

Current Network Status and Potential Applications of GLONASS

As of today, there are 11 healthy GLONASS satellites.  Thirty-one (31)
stations continue to track these satellites and send the data to the Global
Data Centers on a voluntary basis.  Several groups continue to compute
precise orbits using these data, and the timing community is applying these
orbits in their time transfer work.  Two of the manufacturers of
dual-frequency GLONASS receivers confirmed at the workshop that they will
continue to make receivers available and will support the ones that are
already operational.  

Now that we have overcome the major obstacles that limited the use of
GLONASS in the past, there are a number of applications that could benefit
from the availability of GLONASS observations and orbits.  These include
atmospheric studies, geodesy, definition of the ITRF, force modeling
studies, time transfer and orbit prediction.  The combined GPS and GLONASS
constellations are also a good model for future Global Navigation Satellite
Systems that may consist of several independent, integrated satellite
systems. Many potential applications take advantage of GLONASS as an
augmentation to GPS, not as a stand-alone system.  Thus, the current number
of usable GLONASS satellites and the lack of a full constellation are not
critical at this time.  This may become an issue if the number of usable
satellites drops precipitously and no new launches take place.

Workshop Resolutions and Future Plans for a GLONASS Pilot Service

Gerhard Beutler presented a number of resolutions for a vote at the end of
the workshop.  Since many of the active participants in the experiment were
present at the workshop (along with other individuals who had sufficient
interest to pay the registration fee and attend the meeting), the Steering
Committee felt that this group should decide (1) whether or not to continue
IGEX, and (2) what form this activity should take.  The workshop
participants voted in favor of all the resolutions with the following
results:

1. Global, internationally coordinated GLONASS tracking and orbit
determination shall continue in the time interval 1999-2003.
2.  The International Association of Geodesy's Committee for the
Coordination of Space Techniques for Geodesy and Geodynamics (CSTG) and the
International GPS Service (IGS) shall continue to collaborate in an
International GLONASS "Pilot Service".   This service will be organized
according to the rules stated in the memorandum "IGS Policy for the
Establishment of IGS Projects and Working Groups" (available through the IGS
Central Bureau Information System at < http://igscb.jpl.nasa.gov>). 
3.  The International GLONASS "Pilot Service" will be proposed as an IGS
Pilot Project, initially for the time period 1999-2003.

A new Steering Committee will be formed to (1) prepare a charter for the
"Pilot Service", (2) define the duration of the "Pilot Service" as
1999-2003, (3) prepare and send out a new Call For Participation, including
a Central Bureau function, and (4) draft an e-mail message that would
officially announce the creation of the "Pilot Service".  These documents
together with a list of Steering Committee members and the proposed
relationship between the Pilot Service and the IGS shall be sent to the
Chairman of the IGS Governing Board with the request to put the proposal on
the agenda of the December 1999 Governing Board meeting.  Should the IGS
Governing Board decide not to accept the Pilot Service as a pilot project,
CSTG has offered to continue the GLONASS operations under its charter.  The
official Call for Participation will be issued in January 2000.  After the
resolutions were approved, I was asked to Chair the new Steering Committee,
at least on an interim basis, and I have agreed to do so.

The International GLONASS Pilot Service (IGLOPS) will have the following
goals and objectives:

1.  Establish and maintain a global GLONASS tracking network
a.  Apply IGS network operations standards
b.  Calibrate and evaluate combined GPS/GLONASS receivers and antennas 
2.  Produce precise (10-cm level) orbits, satellite clock estimates, and
station coordinates 
a.  Evaluate microwave-derived orbits using SLR observations and orbits
b.  Incorporate SLR observations in routine orbit processing
c.  Obtain initial operational capability of 20-50 cm orbits at Analysis
Centers 
d.  Receive independent orbit/clock/station solutions from Analysis Centers
within 3 weeks of 
     observations
3.  Monitor and assess GLONASS system performance 
4.  Investigate the use of GLONASS to improve Earth Orientation Parameters
5.  Improve atmospheric products of the IGS
6.  Fully integrate GLONASS into IGS products, operations and programs.

The Call for Participation will request recommitment from the existing
GLONASS stations that continue to track and will invite new stations to
join.  Organizations will also be asked to participate as Analysis Centers,
Data Centers and a Central Bureau.  Requirements for all these activities
will be given in the Call for Participation.

If you have any comments or suggestions, I would very much like to hear
them.

Jim Slater,
Chair, IGEX-98 Workshop Organizing Committee 
and  Interim Chair, International GLONASS Pilot Service Steering Committee

 <<igxstatus.rtf>>  <<igex-status&plans.doc>> 
............................................................................
.........................
JIM SLATER        (301)227-2899      Fax: (301)227-4749     E-mail:
[email-masked]
NIMA, GICS, MS D-68, 4600 Sangamore Rd., Bethesda, MD 20816-5003, U.S.A.

"If it weren't for the last minute, a lot of things wouldn't get done." -
Michael S. Traylor