Samen meten, beter weten
Voordrachten gehouden ter gelegenheid van de opening van het Astrometrisch-Geodetisch Observatorium te Westerbork, 24 september 1999
L. Aardoom (redactie)
Nederlandse Commissie voor Geodesie 38, Delft, 2000, 49 pages.
ISBN-13: 978 90 6132 272 6. ISBN-10: 90 6132 272 3. € 10.00
Preface
The installation of the Westerbork Astrometric-Geodetic Observatory was
an important step to a more effective use of advanced astronomic and
geodetic equipment in The Netherlands. The geographic junction uniting this
equipment, prompted by a strive for a more efficient spending of funds on
behalf of the Delft University of Technology, offered possibilities of
renewed geodetic and geodynamic research and of improvement of the
individual meas-urement techniques. A more intensive use of
extra-terrestrial space, enabled by artificial satellites, had brought
geodesy in a renewed functional relationship to astronomy. This new
relationship emanates from the joint utilization of space and of the
platform of measurement: the Earth. The long standing tradition of dialogue
between both sciences in the Netherlands Geodetic Commission (NCG) called
for a joint exploration of the added value the geographic junction of
equipment as mentioned could have scientifically. In May 1997 this led the
Commission to setting op a taskforce to perform such exploration.
In November 1998 the taskforce reported its findings as regards a scientific
policy to follow. The deployment of the observatory for geometric anchoring
of The Netherlands in a global context with emphasis on the height component
involved is the central item of these find-ings. Noting the probably ongoing
and possibly increasing rate of relative rise of the North Sea level, this
component is presently particularly important to our country. It is
precisely the height component however, which has up till now been
determined least accurate in space geodetic positioning. Improvement of the
measuring, analysis and interpretation procedures should therefore primarily
focus on height. Long continuous datarecords, acquired side-by-side from the
individual techniques offer the best possibilities in this respect. The
observatory’s programme should meanwhile be associated with global efforts
to establish and maintain geodetic reference systems and frames. The
parallel application of observing techniques will also provide geodetic
support to the measurement and analysis procedures of astronomic VLBI in
general. The observatory will support related investigations in space, e.g.
of the atmosphere, which interferes in Earth based space measurements. An
important aspect of the junction of instrumentation is that it brings
together the people who work with the instruments and with them the
knowledge they have. The integration of that knowledge promises a great deal
of added value.
September 24, 1999 was the date of the official inauguration of the
observatory. Partners - the Foundations of Astronomisch Onderzoek Nederland
(ASTRON) and of the Joint Institute for VLBI in Europe (JIVE), the Delft
University of Technology (TUD) and the Meetkundige Dienst van de
Rijkswaterstaat (MD) - decided that this occasion should not pass unnoticed
and they convened a symposium at the main office of ASTRON at Dwingeloo,
inviting speakers to talk on various aspects of the co-operation as foreseen.
After this symposium partners were to sign an agreement to work out a
scientific programme along the lines traced out by the taskforce. The formal
part of the convention, which attracted about 60 participants, was concluded
by a visit to the observatory at Westerbork.
The lectures presented at the symposium are reproduced hereafter, partly in
Dutch, partly in English. Prof.Dr. H.R. Butcher and Prof.Dr.ir. M.J.M.
Bogaerts touch upon the plans from the management points of view on behalf
of ASTRON and TUD, respectively. Prof.Dr.Ir. P.J.G. Teunissen memorize de
traditional co-operation between astronomers and geodesists, in NCG-circles
in particular. Prof.Dr. R.T. Schilizzi gives an outline of VLBI. Prof.Dr.Ir.
L. Aar-doom reviews the history of satellite geodesy. Ir. E.J. Riedstra
presents the NAP height system as related to the observatory. Prof.Dr.-Ing.habil.
R. Klees elaborates on the planned scientific programme of the observatory.
An executive summary (in Dutch) of the taskforce's report is appended to the
present symposium proceedings.
Mr. F.H. Schröder collected the material, prepared it for publication and
took care of the layout of these proceedings.
L. Aardoom
Contents
| - | Voorwoord, prof.dr.ir. L. Aardoom |
| - | Preface, prof.dr.ir. L. Aardoom |
| - | Welcome word, prof.dr. H.R. Butcher |
| - | Astronomy applied to Land Surveying, prof.dr.ir. M.J.M. Bogaerts |
| - | Astronomy, Geodesy and The Netherlands Geodetic Commission, prof.dr.ir. P.J.G. Teunissen |
| - | VLBI – an astrometric technique with geodetic unknowns, prof.dr. R.T. Schilizzi |
| - | Lengte, breedte en hoogte met satellieten, prof.dr.ir. L. Aardoom |
| - | De hoogte, Rijkswaterstaat een zorg . . . , ir. E.J. Riedstra |
| - | Het Astrometrisch-Geodetisch Observatorium te Westerbork als fundamenteel referentiestation, prof.dr.-Ing.habil. R. Klees |
| - | Aanhangsel. Bestuurlijke samenvatting van het rapport 'De wetenschappelijke rol van het astrometrisch-geodetisch observatorium te Westerbork. Uitkomsten van een verkenning door de Taakgroep Geodetisch-Astronomisch Station Westerbork'. |