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Division of Geodesy

This page gives a summary of the activity fields and organization structure of the division of geodesy.
Descriptions for geodetic reference systems, their realizations and work arising from, you can find in menu Reference Systems and in menu Information Systems and Web Applications an overview of geodetic informationsystems and webapplications.

Picture shows a collage of different measuring techniques like laser, gravimetry, GPS and VLBI Collage of different measuring techniques

Tasks and responsibilities

The provision and realization of uniform gravity reference networks for the Federal Republic of Germany constitutes the core task of the Division of Geodesy. These fundamental data form the basis for the referencing of geoinformation as well as for navigational purposes and investigations on earth observation, as e.g. with regard to environmental changes. The national reference systems are part of European and global reference systems.

Provision and maintenance of the geodetic reference networks of the Federal Republic of Germany make considerable demands on the personnell of the Division of Geodesy concerning surveying techniques and theoretical performances required for collecting and editing the relevant measuring data, cooperating in bilateral and multilateral works performed for the determination and maintenance of the European and global reference systems, the further development of the measuring and observation techniques employed, and the representation of the relevant interests of the Federal Republic of Germany at an international level.

The activities of the Division of Geodesy can be divided into three groups:

Realization of the geometric reference systems for the acquisition of the geometry of the earth's surface,
Realization of the gravimetric reference systems as a basis for the acquisition of the earth's gravity field and,
Determination of the earth's rotation parameters for the description of the earth's movement in space.

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Products of the national geodetic reference systems

Integrated German Geodetic Reference Network

The central task of the division of geodesy is to further extend the Integrated German Geodetic Reference Network GREF in order to make up an GNSS real-time network. On the GREF stations gravity observations are carried out and at the coastlines tide gauge records are integrated. The different sensors are connected through local station networks and secured. The GREF stations are attached to the German Basic Vertical Control Survey Net (DHHN). Many GREF stations are by their measurements involved in international projects.

The Integrated German Geodetic Reference Network (GREF) serves the standardization of the spatial reference of the Federal Republic of Germany. GREF stations are an integral part of the European GNSS Permanent Network (EPN) and of the International GNSS Service (IGS) for Global Navigation Satellite Systems (GNSS). GREF constitutes the basis for the satellite positioning network of the German National Survey - SAPOS.

BKG (Federal Agency for Cartography and Geodesy) participates in the determination of precise orbits for satellites of the navigation systems GPS and GLONASS, the derivation of up-to-date coordinates within the frame of the European Terrestrial Reference System (ETRS89), the computation of static and variable parameters of the earth’s gravitational field as well as in tasks related to the transformation of coordinates. Therefore, BKG (Federal Agency for Cartography and Geodesy) also has the function of a data centre for the European Vertical Reference System (Informationsystem EVRS).

The aim of the gravimetric works of BKG (Federal Agency for Cartography and Geodesy) consists in realizing a precise and uniform Gravity Standard for the Federal Republic of Germany. The Gravity Network West Germany (DSGN) refers to the International System of Units (SI). The DSGN is to be preserved and forms the basis for the computation of gravity anomalies and geoid models. In cooperation with neighbouring countries a uniform European gravity reference system is being established.

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Involvement in research and development projects

The Division of Geodesy cooperates within the frame of research and development projects with other scientific agencies and economic institutions.

With the program "Geotechnologies – key area: Observation of the system earth from space", which is promoted by the BMBF (Federal Ministry for Education and Research) and the DFG (German Research Community), the Division of Geodesy cooperates in two projects:

In GGOS-D – Integration of the spatial observation techniques as basis of a global geodetic-geophysical observation system a data and information system is developed for the purpose of a global geodetic observation system.
In the case of GOCE-Grand II – GOCE Gravitational field analysis Germany II contributions from terrestrial gravimetry are made to the regional validation and calibration experiment for the needs of the satellite-borne gravity field mission GOCE.

Further, BKG (Federal Agency for Cartography and Geodesy) participates within the frame of the DFG (German Research Community) research group “Earth Rotation and Global Physical Processes” in the development of a virtual earth rotation and information system.

For the purpose of developing the European navigation system GALILEO BKG is, within the scope of several consortia, involved in three FP6 development projects performed by the European Commission. In the project GGSP the geodetic GALILEO spatial reference system is defined and tested. The project GIGA develops strategies for the use of GALILEO and EGNOS in the areas energy and GIS. Further, within the project GALIEA the generation of integrity data for GALILEO and EGNOS from local networks is investigated.

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International services

Within the frame of the International Earth Rotation and Reference System Service (IERS), whose Central Bureau is run by BKG (Federal Agency for Cartography and Geodesy), the worldwide networks employed by the different space techniques are combined with each other for the purpose of deriving the global International Terrestrial Reference System (ITRS), the International Extraterrestrial Reference System (ICRS) as well as the earth rotation parameters.

With the establishment of the International VLBI Service for Geodesy and Astronomy (IVS) and the International Laser Ranging Service (ILRS), the groupings of international scientists until then more or less loosely connected were replaced through well-structured organizations. Besides its observational contributions made to the global reference networks (Fundamental Station Wettzell, TIGO and O’Higgins), BKG (Federal Agency for Cartography and Geodesy) takes part in both International Services as an analysis centre and for the IVS also as a global data centre. Coordination of the International Services is taken care of by the International Association of Geodesy (IAG).

In consultation with EUREF and EuroGeographics an information system for German and European Coordinate Reference Systems (CRS-EU) was developed, which constitutes the basis for describing the spatial reference of geoinformation systems and includes information on the transformation of coordinate (Information system CRS-EU).

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Geodetic Observatories

BKG (Federal Agency for Cartography and Geodesy) operates three geodetic observatories. Given their combination and the direct comparability of the different observation techniques the Wettzell Observatory and the Transportable Integrated Geodetic Observatory (TIGO) are called fundamental stations. Very long baseline (VLBI) observations to quasars, laser rangings to satellites (SLR) and to the moon (LLR) as well as the satellite positioning systems GPS and GLONASS are made use of.

The geodetic Observatory Wettzell (latitude: N 49° 08’, longitude: E 12° 52’) is operated within the frame of the Research Group Satellite Geodesy (FGS). In addition to the techniques mentioned above a ringlaser has been operated since 2001 at the station Wettzell for the purpose of observing short-periodic variations in the earth’s rotation.

View of the geodetic Observatory Wettzell

Presently, TIGO (latitude: S 36° 50’, longitude: W 73°01’) is employed at Concepcion, Chile. It is operated jointly with a consortium directed by the University of Concepcion / Chile.

TIGO in Concepcion, Chile