[IGSMAIL-3216]: Summary, IGS LEO Pilot Project Meeting Feb. 6-8, 2001
Ruth E. Neilan
ruth.neilan at jpl.nasa.gov
Wed Feb 28 17:31:01 PST 2001
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IGS Electronic Mail 28 Feb 17:31:03 PST 2001 Message Number 3216
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Author: Chris Reigber, Ruth Neilan, Angie Moore and Mike Watkins
Subject: Summary, IGS LEO Pilot Project Meeting Feb. 6-8, 2001
Dear colleagues,
This message provides a summary of the recent IGS LEO Pilot Project
meeting held February 5-8 at the GeoForschungsZentrum, Potsdam,
Germany. The general conclusion of the attendees was quite positive
for this effort as you will see from the summary. The meeting agenda
is detailed in IGSMail message #3193 and can be accessed at:
http://op.gfz-potsdam.de/D1/LEOW/LEOW_index.html
The participant list is also attached below for completeness.
Following the LEO PP meetings was an ad-hoc meeting concerning
real-time activities within the IGS. At the last IGS Governing Board
meeting in December there was a strong consensus that the IGS should
establish a Real-Time Working Group (RTWG) to address and assess
issues involving the IGS moving towards real-time infrastructure and
processes. Generally, an IGS working group is established when a
group develops a charter, project plan and designates a chair, and
then comes to the Board for approval. In this case, the GB identified
this as a critical new activity, proposed a draft charter, and asked
the CB to organize the ad-hoc meeting during the venue of the LEO PP
meetings in Potsdam to explore and initiate the formation of such a
working group. Additional information on this productive meeting
will be forthcoming in the very near future.
Message Contents
----------------------------
Overview
Summary Tuesday February 6
Wednesday, February 7 Overview
Proposal Descriptions
Analysis/Associate Analysis Center Discussion Summary
Network/Station & Data Center Proposals and Plans
Format Discussions
Data Center Issues
LEO PP Designated Agency/Points of Contact
IGS LEO Working Group Members
LEO Project Meeting Participants List
Overview
--------------------------------------
The primary purpose of this meeting was devoted to understanding
upcoming LEO missions carrying GPS flight receivers, with particular
emphasis on CHAMP, in order to develop the goals, objectives and
structure for the IGS LEO Pilot. There were over 70 people attending
this meeting and it was quite evident that this project has sparked
great interest within agencies planning LEO missions, as well as the
IGS components that are well positioned to be involved in these new
activities. This ranges from ground network support, to data
handling, to analyses of the flight data, POD, etc. It is clear that
the spaceborne GPS will revolutionize atmospheric and ionospheric
science over the next decade, similar to the revolution experienced
in Earth geodesy in the last.
Summary Tuesday, February 6
---------------------------------------
The morning of the first day was devoted to an overview of the CHAMP
mission. Details on the satellite state and performance were provided
with an overview of each, the satellite, science instruments, ground
support and data archive, provided by the responsible member of the
CHAMP Team. The overview by the CHAMP Team provided insight into the
technical aspects, challenges and successes of the mission. Since the
launch in July 2000 all satellite subsystems, payload instruments,
mission operations and mission control are performing very well. The
science ground segment is in the final stage of the accommodation and
calibration/validation phase. RO capability has been enabled only
recently with the upload of the new GPS receiver software. For this
task the calibration/validation phase has just started. The CHAMP
rapid science orbit determination is achieving 10cm orbits for the
GPS satellites and produces 15cm to 30cm CHAMP orbits, 1/2 day and
one day arc lengths respectively. SLR data are employed for
operationally producing CHAMP orbit predictions and for CHAMP GPS POD
validation with an independent data source. Since the meeting, the
GPS radio occultation data have successfully been received and
analyzed, see the CHAMP website for details. As this new capability
becomes routine it is expected that CHAMP will produce about 200
occultations per day. From only a few days' worth of of CHAMP GPS
and accelerometer data it has been possible to tune the global Earth
gravity field model resolution taking into account terms up to
degree/order 70, already resulting in a considerable accuracy
improvement for a 5x5 degree geoid representation.
Earth magnetic field models have also already been derived
successfully from the scalar magnetometer data and are compared with
OERSTED and MAGSAT results. Work is going on to include vector and
magnetometry data now.
The afternoon was devoted to presentations of LEO Missions Status and
Plans and LEO Flight GPS Analysis. Overviews and science objectives
were presented on SAC-C, GRACE, ICESat/GLAS, Jason, COSMIC and the
various requirements of each. There was collective agreement that IGS
clocks at 30s or 10s would be of great value to these missions. The
GPS flight instrument onboard these missions as well as CHAMP is the
JPL Blackjack receiver. Members of the JPL team described the
characteristics of the receiver. The SAC-C, a joint Argentine-US LEO
mission, successfully launched in November 2000 uses this same
receiver, and data are available from JPL. SAC-C is at an altitude of
~700 km and preliminary orbit determination results from JPL are
below 10cm level. GRACE and JASON which both launch later this year
will also carry the Blackjack.
In November 2000, a CHAMP data set was released for August 7, 2000
(DOY 220) containing complete files of the operating instruments.
This public data set is available at the CHAMP website. The last
session of the day included presentation on analysis of this data
set, and plans for future analysis, software tools, and methodology.
Representatives from CNES noted that JASON will provide a good data
set for POD studies, it will have both GPS and DORIS on-board as well
as SLR tracking. JASON and ICESat/GLAS do not plan occultation
measurements.
Summary requirements:
- IGS 10-30sec clocks
- JASON 1cm radial orbit accuracy
- Retrieval of occultation profiles require <0.1mm/sec velocity
determination and ~10cm LEO POD
- 10-15 minute latency of ground data eventually required for
numerical weather prediction
- Use accelerometer data to accurately account for drag and other
surface forces
- Improved gravity field needed for analysis of CHAMP data
Wednesday, February 7 Overview
-----------------------------------------
Mike Watkins, Chair of the LEO Working Group, gave an overview and
history of the IGS LEO activities thus far. The call for
Participation had highlighted POD of LEOs, evaluation of improvements
to IGS "classic" products, and data flow and management given the
required high-rate, low-latency requirements of LEO analysis. This
was the largest CFP since the inception of the IGS. He noted that it
will be important to review IGS Analysis Standards and the new IERS
standards, enlisting the assistance of the new IGS Analysis
Coordinator, Robert Weber. It was noted that model refinements, e.g.
concerning Earth tide, phase lags, Love numbers, etc. get very
important for lower Earth satellites.
A proposed phased approach to the pilot project was presented:
* Begin with SAC-C data ASAP (1 Mar?): producing LEO orbits, acquire
selected periods of high-rate ground data for RO support to test data
flow
* Add CHAMP data as it becomes available in May/June: Improve orbit
determination & study impact on IGS classic products, refining data
flow for full occultation support
* Add JASON (Nov '01): Compare GPS orbits to SLR and DORIS; study
effect on IGS classic products
The pilot project should have a defined end; 31 Dec 01 was suggested.
The morning was devoted to brief proposal descriptions from the
groups participating in analysis efforts for the LEO project, and the
afternoon focusing on network and data center proposals.
Proposal Descriptions
------------------------------
JPL/Webb
Frank Webb described activities with respect to JPL's role as an IGS
Analysis Center, generating the 'classic' products on a daily basis.
JPL will upgrade more sites to hourly or better availability with a
significant number offering high-rate data. As a data center, JPL
will provide hourly & high rate data. Production of the IGS ultra
product (igu) will resume, improving with long arcs and reducing
latency from 12hr to 6hr. Currently they provide 30s clocks from 5min
estimates; proposed 1s from 5 min estimates & 1s ground data. Now
that SA is off, a new proposal is to investigate interpolation &
extrapolation for 1s GPS clocks from 5 min estimates & high rate
ground data.
JPL/Muellerschoen
Ron Muellerschoen described JPL's proposed role as an Associate
analysis Center for the LEO pilot project. He anticipates POD daily
or subdaily final within one month. Usage is to extract atmospheric
refractivity of occulting signal. Velocity should be known to 0.1mm/s
(for occultation) and position to ~10cm. Also looking to gravity
recovery & magnetometer. Current latency (CHAMP) of 3 weeks to be
reduced to ~3 days with a dual approach for rapid products (for s/c
validation; goal 6hrs for atmospheric studies) and final products.
LEO phase ambiguity resolution is done with ground stations. CHAMP
star tracker & accelerometer data help; 4cm pitch error gives a 10cm
radial offset. A run every 6 hrs to get predicts will provide
ephemerides for NWP (troposphere to be ingested every 6 hrs). Current
real-time GPS orbit results are at ~30-40cm. A question on the
velocity results will be verified.
GFZ/Koenig
Rolf Koenig described GFZ role as an Associate Analysis Center (AAC)
to provide predicted, rapid science, and postprocessed science orbits
for CHAMP and the GPS satellites. Rapid science orbits are computed
with a 3 hour turn-around time to support RO activities.
Postprocessed science orbits include 30s clocks and are primarily
used for gravity recovery. POD may be done for other data (e.g.,
SAC-C, JASON, etc.) but CHAMP activities must take priority.
Presently used software version in use is GFZ's EPOS-V5.2OC.
ASI/Vespe
Francesco Vespe said that MATE, the station at Matera station is
proposed as a high rate station. AAC was also proposed. Since
submitting proposal:
- ASI plans for POD and radio occultation remote sensing mission in
the next few years (GPS/GLONASS receiver, Lagrange). Italy provides
the attitude control of SAC-C
- Also planning a climatology mission, not yet selected, with
GPS/GLONASS receiver for POD + occultations, and an infrared
spectrometer.
Other stations to be added: MALI (GPS/GLONASS) and Peru due to other
missions (but high-rate uncertain). Can process CHAMP data in
calendar 2001. On SAC-C Lagrange L2 SNR is not good, nor is the
second frequency the GLONASS channels. Improvements expected in next
version on other satellites.
AIUB/Hugentobler
Bern's main interest is POD via epoch-wise code & phase differences
and clock extractions from IGS ephemerides. Propose: pilot phase LEO
POD when quality data is available to demonstrate real-time LEO POD,
and improve models & data editing. After the pilot phase, AIUB will
make a decision about continuing support. They plan to
- evaluate impact on IGS products when combination available (not near future)
- not prepared for combination of LEO orbits due to Springer's
departure but ready to develop tools for comparison
- study predict quality & necessary update frequency for desired
accuracy. Standard gravity model is needed for comparison. ACCs
should address (consider GRIM5 & new CHAMP model).
CSR/Schutz
Address impact to IGS orbits, reference frame, EOP. Motivation is
GRACE & ICESAT preparation. CSR will tune the gravity field and
evaluate force models. They can participate in PP in 2001.
CNES/Mercier
CNES main interest is altimetry of the JASON mission. Can participate
certainly until June but not continuously. For JASON require GPS
ephemerides & daily precise GPS clocks.
ESOC/Dow
John Dow described the participation of ESA/ESOC and agreed to assume
the responsibility of the analysis coordination for the project, and
will designate the actual point of contact by the end of March
They will provide high rate data from some stations, act as an AAC
and improve latency & quality of IGS AC products.
His approach will be to request specific project boundaries (select
periods or months of data), comparison of 1 or 2 satellites and that
this would be a part time activity this year. In a few months ESOC
will focus on standards etc, then ramp up the analysis.
OSU/Schutz for Shum
Ohio State proposes two stations: Lake Erie & OSU. They plan to
develop AAC capability using kinematic OD for GPS & LEO using triple
differencing (no ambiguities) OD & atmospheric profiling latency. He
noted that near-real time (NRT) stations are possible.
CISAS/Caporali
Station UPAD can become an hourly stations. They are trying CHAMP
data for improving OD and developing software.
Analysis/Associate Analysis Center Discussion Summary
----------------------------------------------------------------
Watkins questioned whether SAC-C should be a part of PP. Dow felt
that it would be better to prepare standards, details, etc. in
preparation for the CHAMP data release in May. It was agreed that
those interested could experiment voluntarily with the SAC-C data
available from JPL, but it would not be an official part of the
project as yet. Schutz noted that there was little information on the
SAC-C s/c, and Yunck agreed to try to obtain this. Reigber stated
that the IGS participants need not respond to the upcoming CHAMP AO
for general data access.
Network/Station & Data Center Proposals and Plans
------------------------------------------------------------
JPL/Stowers
15 minute data of 1sec data available online at JPL for 2 weeks,
nearline thereafter.
GFZ/Reigber
8 sites of GFZ network are 1Hz data in 15m files and in GFZ's
CHAMP-ISDC data centerin GFZ-BINEX. All stations are available to the
LEO PP and have reliable meteorology instruments with links to WMO.
There are 5 reliable stations for hourly, 30sec data and 3 more
potential.
Pecny/Simek
GOPE station has an operating GPS/GLONASS receiver producing hourly
30 sec data files.
They started a 1Hz sample experiment in Jan 2000 (following Aug 99
solar eclipse campaign). They also propose to be an AAC for NRT
troposphere, with subdaily orbits, and hourly orbits. Their DC
supports NRT data & products. They participate in the COST 716.
NRCan/Caissy
NRCan plans to continue hourly 30s stations, with 12 stations
operating at 1Hz transmitting data to Ottawa. A possible new site far
north is being considered. 15min 1sec files in tcomp (designed
exchange format for GFZ-JPL CHAMP Network) are ready to go from three
stations. They propose AAC for subdaily orbits. Since March, they
produce orbits twice daily via Bernese processing every 3 hours.
KMS/Madsen
High rate data from Thule THU2 is already operating at 1Hz for
Oersted. A new station in southern Greenland is planned this summer.
HERS/Wood
Herstmonceux is already operating hourly and can possibly operate at
1sec. rate.
Format Discussions
------------------------------------------
Werner Gurtner guided the discussion and separated two issues, how
the IGS will handle LEO data for the project, and how the IGS will
move towards a real-time data handling. The latter would be discussed
in the ad-hoc meeting scheduled for February 8.
At the Oslo workshop a 'formats' group was established, co-chaired by
Werner Gurtner and Angie Moore. This discussion focused on file
oriented RINEX and RINEX modifications for the LEO s/c data.
Oslo Network Workshop
| Two data format issues
|
|________________________________________|Real-time
File Oriented RINEX | |
| Real-time Working Group
|
Ground Network |_______________________________________| LEO s/c Data
| |
|_______________|_______________| |
15m 1hr 1 day |
1s 30s 30s |
|
|___________________|_______________|
Occultation POD Auxiliary
1s 30s ?
Orbit exchange,
SP3?
Proposed modification to RINEX to support LEO flight data were
discussed. How to handle multiple antennas on the LEO could either
have separate files for each antenna, or could define antenna # and
cross-references in the header. The group prefers separate files.
SP3 needs only to have "L" code defined for LEO.
Comments on the proposed RINEX would be accepted until 23 February
with a final proposal due 1 March.
Zumberge questioned whether the clock RINEX format could handle LEO
clock information.
(ftp://igscb.jpl.nasa.gov/pub/data/format/rinex_clock.txt)
Hugentobler noted that analysis needs maneuver information and how to
include this. Caporali: wondered if there could be an event flag for
maneuver, but Gurtner was not sure whether such information is
available at the time of RINEXing data.
GFZ suggests using the CHAMP orbit format (CH-ORB) over SP3. They
also recommend to use the CH-ACC rather than a new AUX file. For
description and contents see:
ftp://ftp.gfz-potsdam.de/pub/champ/chftp1/public/champ_data_format_description.txt
The project AACs and the IGS ACs are to be informed of these
discussions and asked for comment until 23 Feb to determine consensus.
Noll said that a naming convention is needed for subhourly files.
Data Center Issues
---------------------------------------
Carey Noll at GSFC/CDDIS proposes to be DC for LEO data for the PP.
This is still to be sorted out since CHAMP data will only be
available from the CHAMP DC at GFZ. There was some discussion about
linking, however, there is no such thing as "linking" in FTP, the
accepted protocol for automated data download. It is expected that
AACs will request unattended automatic transfer of newly received
data. The GFZ in response to the LEO PP CfP proposed to also be a DC
for the project. Bernd Ritschel reported that registration is
required for first access to the CHAMP Information
System and Data Centre (ISDC). Product archiving, administration and
retrieval are organized by the CHAMP ISDC at GFZ Potsdam, which also
is the users' www- and ftp-based interface for access to all
scientific data and products. There is no support for a "new
requirement" of unattended automated download. A "Batch Agent" to be
active for regular operations is under development.
Tom Yunck gave an overview of the new GPS Environmental & Earth
Science Information System GENESIS. This information system is a
member of the Federation of Earth Science Information Partners (ESIP)
see:
http://genesis.jpl.nasa.gov/
Access is unrestricted for GENESIS, however in the future it is
expected that users will register (no cost) so that access statistics
can be compiled.
It was decided that Moore, Noll, Ritschel, Yunck, and Stowers will
compile access instructions for various data types analogous to
current .dcn files located at the Central Bureau (which may need
alteration).
A LEO PP mail listing has been established for the project by the
Central Bureau and on-going communications can be viewed at IGSLEO
Mail:
http://igscb.jpl.nasa.gov/mail/mailindex.html
LEO PP Designated Agency/Points of Contact:
-------------------------------------------------------------
Proposal received:
Agenzia Spaziale Italiana, Matera, Italy/Francesco Vespe
Astronomical Institute, University of Bern, Switzerland/Urs Hugentobler
Center for Space Research, Univ. of Texas-Austin, USA/Bob Schutz
CNES, Toulouse, France/ Analysis: Jean-Paul Berthias, Stations: Louis
Duquesne, (David Assemat)
ESA/ESOC, Germany/John Dow
GeoForschungsZentrum Potsdam, Germany/Ch. Reigber
Indian Space Research Organization, Tracking and Command Network/K.
Elango (S.K. Shivakumar)
Institut Cartographic de Catalunya, Spain/Julia' Talaya
Jet Propulsion Lab/Jim Zumberge
Jet Propulsion Lab, & Univ. Sth. California/Tom Yunck
Korean Astronomy Observatory,/Pil-Ho Park
Laboratory for Space Geodesy and Remote Sensing - Ohio State, USA/C.K. Shum
NASA Goddard Space Flight Center, CDDIS, USA/Carey Noll
Natural Resources of Canada, Geodetic Survey /Mark Caissy,(Norman Beck)
National Survey and Cadastre - Denmark/Per Knudsen
Norwegian Mapping Authority/Rune Hannsen
Research Institute of Geodesy, Pecny, Czech Republic/Jaroslav Simek
NERC Space Geodesy Facility, UK/Roger Wood
University of New Brunswick, Dept. of Geodesy and Geomatics
Engr./Richard Langley, Sunil Bisnath
University of Padua, Center for Space Studies (CISAS), Italy/Stefano Casotto
University of Padua, CISAS, Italy/Alessandro Caporali
US Naval Observatory, USA/Jim Ray
Letter of Intent received:
Australian Surveying and Land Information Group/Ramesh Govind
University Consortium for Atmospheric Research/Chris Rocken
Joint Center for Earth Systems Technology, Univ. Maryland/Erricos Pavlis
IGS LEO Working Group Members
---------------------------------------------
John Dow
Ruth Neilan, IGS CB
Christoph Reigber
Chris Rocken
Markus Rothacher
Bob Schutz
Tom Yunck
M. Watkins (WG chair)
R. Weber, IGS ACC
LEO Project Meeting Participants List, Feb 6-8, 2001
-----------------------------------------------------
1. Gerald Baustert, TeleOrbit, Germany (gbau at gfz-potsdam.de)
2. Georg Beyerle, GFZ, Germany (gbeyerle at gfz-potsdam.de)
3. Heike Bock, AIUB, Switzerland (heike.bock at aiub.unibe.ch)
4. Ralf Bock, GFZ, Germany (ralf.bock at gfz-potsdam.de)
5. Mark Caissy, NRC, Canada (caissy at nrcan.gc.ca)
6. Alessandro Caporali, University of Padova, Italy (alex at geol.unipd.it)
7. Stefano Casotto, University of Padova, Italy (casotto at pd.astro.it)
8. Wolfgang Dick, BKG, Germany (dick at ifag.de)
9. John Dow, ESA/ESOC, Germany (john.dow at esa.int)
10. Louis Duquesne, CNES, France (louis.duquesne at cnes.fr)
11. Lou Estey, UNAVCO/UCAR, USA (lou at unavco.ucar.edu)
12. Kevin Fleming, GFZ, Germany (kevin at gfz-potsdam.de)
13. Christoph Foerste, GFZ, Germany (foer at gfz-potsdam.de)
14. Roman Galas, GFZ, Germany (galas at gfz-potsdam.de)
15. Carlos Garcia, ESOC, Germany (Carlos.Garcia-Martinez at esa.int)
16. Gerd Gendt, GFZ, Germany (gendt at gfz-potsdam.de)
17. Gianluca Graglia, Alenia Spazio, Roma, Italy
(g.graglia at roma.alespazio.it)
18. Serge Gratton, CNES, France (serge.gratton at cnes.fr)
19. Ludwig Grunwaldt, GFZ, Germany (grun at gfz-potsdam.de)
20. Werner Gurtner, AIUB, Switzerland (gurtner at aiub.unibe.ch)
21. Phillip Hartl, Germany (ph.hartl at t-online.de)
22. Finn Hass, Terma, Denmark (fah at terma.com)
23. Stefan Heise, DLR, Germany (stefan.heise at dlr.de)
24. Urs Hugentobler, AIUB, Switzerland (urs.hugentobler at aiub.unibe.ch)
25. Klaus-Peter Johnsen, GKSS, Germany (johnsen at gkss.de)
26. Zhigui Kang, CSR, USA (Kang at csr.utexas.edu)
27. Wolfgang Koehler, GFZ, Germany (wolfk at gfz-potsdam.de)
28. Rolf Koenig, GFZ, Germany (koenigr at gfz-potsdam.de)
29. Jakub Kostelecky, Pecny Obs., Czech Republic (gope at asu.cas.cz)
30. Jan Kostelecky, Prague Techn. Univ., Czech Republic
(kost at fsv.cvut.cz)
31. Gerhard Kruizinga, JPL, USA (Gerhard.Kruizinga at jpl.nasa.gov)
32. Hermann Luehr, GFZ, Germany (hluehr at gfz-potsdam.de)
33. Finn Bo Madsen, KMS, Denmark (bm at kms.dk)
34. Christian Marquardt, GFZ, Germany (marq at gfz-potsdam.de)
35. Franz-Heinrich Massmann, GFZ, Germany (fhm at gfz-potsdam.de)
36. Charles Meertens, UNAVCO/UCAR, USA (chuckm at unavco.ucar.edu)
37. Bill Melbourne, GFZ/JPL, Germany/USA (wgm at gfz-potsdam.de,
william.g.melbourne at jpl.nasa.gov)
38. Flavian Mercier, CNES, France (flavien.mercier at cnes.fr)
39. Angelyn W. Moore, JPL, USA (Angelyn.W.Moore at jpl.nasa.gov)
40. Ron Muellerschoen, JPL, USA (rjm at cobra.jpl.nasa.gov)
41. Antonio Nardi, Telespazio, Roma, Italy (antonio at sidus.mt.asi.it)
42. Ruth E. Neilan, JPL, USA (ruth.neilan at jpl.nasa.gov)
43. Roland Neuber, AWI, Germany (neuber at awi-potsdam.de)
44. Karl-Hans Neumayer, GFZ, Germany (neumayer at gfz-potsdam.de)
45. Carey Noll, GSFC, USA (noll at cddis.gsfc.nasa.gov)
46. Kurt Oppitz, BKG, Germany (kop at potsdam.ifag.de)
47. Markus Ramatschi, GFZ, Germany (maram at gfz-potsdam.de)
48. Christoph Reigber, GFZ, Germany (reigber at gfz-potsdam.de)
49. Hyung-Jin Rim, CSR, USA (rim at csr.utexas.edu)
50. Bernd Ritschel, GFZ, Germany (rit at gfz-potsdam.de)
51. Chris Rocken, UNAVCO/UCAR, USA (rocken at unavco.ucar.edu)
52. Uwe Schaefer, BKG, Germany (ufer at potsdam.ifag.de)
53. Torsten Schmidt, GFZ, Germany (tschmidt at gfz-potsdam.de)
54. Bob Schutz, CSR, USA (schutz at csr.utexas.edu)
55. Volker Schwieger, GFZ, Germany (schwieg at gfz-potsdam.de)
56. Peter Schwintzer, GFZ, Germany (psch at gfz-potsdam.de)
57. Jaroslav Simek, Pecny Obs., Czech Republic (gope at asu.cas.cz)
58. Dave Stowers, JPL, USA (dstowers at jpl.nasa.gov)
59. Drazen Svehla, TU Munich, Germany
(svehla at step.iapg.verm.tu-muenchen.de)
60. Byron Tapley, CSR, USA (tapley at csr.utexas.edu)
61. Francesco Vespe, ASI, Italy (vespe at asi.it)
62. Pieter Visser, TU Delft, Netherlands (Pieter.Visser at lr.tudelft.nl)
63. Michael M. Watkins, JPL, USA (Michael.M.Watkins at jpl.nasa.gov)
64. Frank Webb, JPL, USA (Frank.H.Webb at jpl.nasa.gov)
65. Robert Weber, Univ. of Technology, Austria
(rweber at luna.tuwien.ac.at, robert.weber at aiub.unibe.ch)
66. Andreas Wehrenpfennig, DLR, Germany (Andreas.Wehrenpfennig at dlr.de)
67. Jens Wickert, GFZ, Germany (wickert at gfz-potsdam.de)
68. Roger Wood, NERC, UK (rw at slrb.rgo.ac.uk)
69. Thomas Yunck, JPL, USA (tom.yunck at jpl.nasa.gov)
70. James F. Zumberge, JPL, USA (james.f.zumberge at jpl.nasa.gov)
--
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
IGS Central Bureau/Jet Propulsion Laboratory
tel: 818-354-8330, fax: 818-393-6686
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