Resolutions of the
Communications Research Laboratory

Tokyo, Japan,
January 27, 1999

The international workshop on Geodetic Measurements by the collocation of Space Techniques ON Earth (GEMSTONE) sponsored by the Science and Technology Agency of Japan was held at the Communications Research Laboratory in Tokyo from January 25 to 27, 1999.


The participants of the GEMSTONE Workshop express their sincere appreciation to the Communications Research Laboratory of Japan and the Local Organizing Committee for their hospitality and excellent arrangements for this very important and beneficial meeting. The participants also thank the Science Committee for its guidance and organization for this meeting.


The GEMSTONE Workshop,

considering that;

a) the collocation of space geodetic measurements (GPS, DORIS, PRARE, SLR, VLBI) is required for the improvement of the terrestrial reference frame;

b) the collocation of space geodetic measurements is of great benefit to improving the performance of the individual space geodetic measurement techniques;

c) high accuracy local ground survey ties between collocated systems are as important as the space geodetic measurements for collocation data analysis;

d) monitoring of the long term stability of site monumentation and calibration targets is indispensable for the interpretation of geodetic results, including collocation analysis; and

e) collocation of geodetic systems on spacecraft is beneficial for accurate positioning in space and on the Earth;

urges the international space geodetic community to:

1) coordinate efforts to improve the reference frame by connecting the different space geodetic techniques through collocation;

2) recognize the importance of local geology in the selection of sites and the need for regularly repeating local surveys to monitor stability;

3) clarify and openly publish the methods and data bases of the ground surveys at each station as well as the results;

4) provide all results in full SINEX format for ease in collocation analysis;

5) consider the implementation of collocated geodetic systems on spacecraft, the Moon and planetary bodies;

6) continue discussions and actions related to the above items through the Geodetic and Geophysical Sites Subcommission (GGSS) of the CSTG in collaboration with the IERS Terrestrial Reference Frame Section;

7) support the establishment of the International Space Geodetic Network (ISGN) site and analysis criteria and their implementation at all major collocation sites;

8) establish regular collaborations among the space geodetic services (IGS, ILRS, and IVS) to enhance collocation activities and to plan joint strategies for exploiting the strengths of the individual techniques; and

9) support the establishment of new collocation sites for improved geographic coverage;


The Workshop also discussed the efficiency and stability that real-time VLBI could provide for geodetic observations, and VLBI's capabilities in Earth rotation monitoring and crustal deformation. The Workshop supports actions to start a real-time VLBI capability through a series of international data communication pilot experiments under the auspices of the International VLBI Service (IVS) Technical Development Centers.

The Workshop also supports active efforts by the IVS Technology Coordinator to develop an international standard for VLBI interfaces that will provide compatibility among heterogeneous VLBI data transport systems, thereby facilitating collocation measurements.

Resolution of the APT/APSG

1) The APT/APSG resolves to undertake a precision VLBI S/X astrometry program in support of the ICRF for Equatorial sources. The APT telescopes have particularly good N-S and E-W coverage with Urumqi and Kokee. Such a program supports both the astrophysical and geodetic goals of the APT/APSG.

2) In the spirit of international friendship and collaboration, the APT/APSG strongly encourages and supports new projects related to the activities of this Workshop. Such projects include:

* The Korean VLBI Network,

* The Japanese precision VLBI astrometry Project VERA,

* The precision astrometry Project SELENE, and

* The regional 1 square kilometre telescope developments in China and Australia.

The APT/APSG believes that these new projects can stimulate the related research activities and also improve the quality of regional scientific research and collaboration.

3) The APT/APSG supports the initiative to develop a standard VLBI Interface Specification, being considered by the IVS. We also encourage the IVS to include the radio astronomy community in this initiative at the earliest possible time.

4) The APT/APSG wishes to encourage closer collaboration between the Astronomy and Geodesy communities, to the advantage of both communities.