Network, Instrumental Improvements and Future Plans of the HartRAO Fiducial Station


Ludwig Combrinck

Hartebeesthoek Radio Astronomy Observatory

Hartebeesthoek, South Africa

June 14, WEGENER 2002, Athens-Greece

                                             Figure 1.   MOBLAS-6 at HartRAO.


HartRAO is currently engaged in several projects which will enhance space geodetic activities
in the southern region of the African continent. Our active role in the major space geodesy
techniques (VLBI, SLR and GPS) are set to change from passive data collection to include
active research and training. This will require transformation, capacity building and new
approaches to meet these objectives.

Our involvement in the southern African region will include specific targets and opportunities
which will elicit active and committed participation of the SADC countries, with set objectives
such as capacity building, development of local expertise and projects which will lead to
community upliftment and poverty alleviation through improved geodetic capabilities. Africa
needs to move from old mapping co-ordinate systems to the latest international standards in
order to develop frameworks for reliable geospatial information or GIS systems. This is a
prerequisite for adequate land management, cross-border management of drainage basins
and the integration of trans-national spatial information.
HartRAO is currently engaged in several projects which will enhance space geodetic activities
in the southern region of the African continent.

Current and Proposed Projects

HartRAO, as a National Facility of the National Research Foundation(NRF) is:

SADC Regional GPS Network

HartRAO and our collaborators are establishing a regional SADC GPS network involving all the Southern African Development Community (SADC) countries, which will be part of the envisaged African Reference Frame (AFREF) network.
The SADC consists of:
South Africa, Lesotho, Botswana, Mocambique, Swaziland, Zambia, Mauritius, Seychelles, Tanzania, Namibia, Zimbabwe, Angola, Democratic Republic of Congo (DRC) and Malawi.
The objectives of SADC include development and economic growth, promotion of self-sustaining development on the basis of collective self-reliance and to achieve complimentarity between national and regional strategies and programmes.
The ultimate objective is to build a region in which a high degree of harmonization and rationalization will enable pooling of resources to achieve collective self-reliance in order to improve the living standards of the people of the region.
Space geodesy and in particular GPS have roles to play in these objectives by facilitating the establishment of reliable geospatial information frameworks that are crucial to effective spatial planning. All geographic information systems must be based on a sound geodetic reference system.
The establishment of a regional (SADC) GPS network, as southern component is an integral part of the sustainable development programmes for the SADC region and supports the objectives of the New Partnership for Africa's Development (NEPAD) programme.
Future stations envisaged to be installed during the remainder of 2002 are:
  Similar installations are planned for the other SADC countries.

Geodetic Institute at HartRAO

The proposed Geodetic Institute at HartRAO has been accepted by the National Research Foundation (NRF) as part of our strategic plan and is fully supported by the President of the NRF. The current Space Geodesy Programme will be transformed into a Geodetic Institute located at HartRAO.
Main objectives of the GI@HartRAO will be to:


IGS TIGA Pilot Project

The Space Geodesy Programme is involved in monitoring the positions of tide gauges
in order to differentiate between long term sea-level changes and long term crustal changes.
This is a global project which will aid and calibrate research data used in global warming and global ocean level studies.

Main objectives of our participation in the TIGA project are:

To attain these objectives we have initiated a working group "TIGA southern Africa" (TIGAsA). Amongst the participants are the SA Navy, (Hydrographic Office), Chief Directorate:Surveys and Mapping, Institute for Maritime Technology, University of Cape Town, Council for Scientific and Industrial Research , JPL (NASA).

The Map (Figure 2) below depicts TIGA Observing Stations' (TOS) data that are being archived by HartRAO for global access. More stations will be added in due time.

Figure 2. TIGAsA TOS which are archived at HartRAO.
Although at the time of writing we have installed only  two TOS stations, a further
installation at Port Nolloth, on the west coast of South Africa is being prepared
in collaboration with JPL (NASA) and the SA Navy.

Radio Telescope Upgrades

Current upgrades to the HartRAO 26 m radio telescope include:


These improvements will:

Figure 3 provides one with a glimpse of the manufacturing of a high precision panel.  The mathematically calculated panel shape is transferred to an extremely rigid metal frame on which is located an array of bolts. These bolts are adjusted to present the exact shape that is required, with the aid of digital measuring probes. A frame is made up to accept the new panel, and using a vacuum and glue process, the panel is forced to take up the shape as set up by the array of bolts. After curing, the panel is measured again. The digital probes are interfaced to a computer to facilitate storing the measured data. This allows necessary statistics and quality control to be done. Average rms error of the panels are below 200 microns.
Figure 4  takes one back to the start of the project (2000),  the perforated panels clearly dominate the surface. Construction of the outer ring has started. Figure 5 indicates progress towards the end of the project (2002).


Figure 4. Installation of a new panel with the aid of a 'cherry

Figure 5. The end in sight, only the inner ring needs to be completed.

Additional Radio Telescope

HartRAO is investigating construction of an additional, more modern antenna.
Current demand for telescope time is more than twice of the available time.
To enable HartRAO to fully support the IVS, we need to construct an additional antenna for VLBI. Currently we support about 56, twenty four hour geodetic VLBI experiments per year. With an additional telescope, this could be increased by a factor of 3. The most feasible way would be to duplicate a current modern (az-el) antenna, such as the MOPRA 22m antenna.


Proposed IAG Outreach Branch

HartRAO has answered the call for participation in the IAG Outreach Branch with a proposal.
Main points of our proposal are:
  • The IAG outreach branch be part of the Geodetic Institute at HartRAO. Many objectives are similar or complimentary.
  • HartRAO would provide long term commitment, office facilities, supporting logistics as well as a real vested interest in the objectives of the Outreach Branch.
  • Develop membership, publish electronic newsletter.
  • Promote the objectives of the IAG.
  • Be uniquely positioned to create resource base for educators, third world countries (most are in Africa anyway) and the global community.
    Viewing a global map of geodetic facilities and active research groups, Africa is highlighted by absence of IAG presence. Surely for an 'outreach' to be meaningful, you need your feet on the African continent.

    Contact Information

    Dr Ludwig Combrinck
    Space Geodesy Programme
    PO Box 443
    South Africa

    Phone: +27 12 326 0742
    Fax: +27 12 326 0756