Günter Seeber

• Professor at Leibniz Universität Hannover

The method of geometric-astronomical leveling is presented as a suited technique for the validation of GNSS (Global Navigation Satellite System) heights. In geometric-astronomical leveling, the ellipsoidal height differences are obtained by combining conventional spirit leveling and astronomical leveling. Astronomical leveling with recently develop...

At the beginning of the 21 st century, a significant technological change took place in geodetic astronomy. In Zurich and Hannover, digital zenith camera systems were developed based on digital imaging sensors (CCD) that strongly improved the degree of automation, efficiency and accuracy of the observation of the direction of the plumb line and its...

This paper analyses the accuracy of vertical deflection measurements carried out with the Digital Zenith Camera System TZK2-D, an astrogeodetic state-of-the-art instrumentation developed at the University of Hannover. During 107 nights over a period of 3.5years, the system was used for repeated vertical deflection observations at a selected station...

2008) Hochpräzise Bestimmung eines astrogeodätischen Quasigeoidprofils im Harz für die Validierung des Quasigeoidmodells GCG05. Zeitschrift für Vermessungswesen (zfv) 133: 108-119. Zusammenfassung Im vorliegenden Beitrag wird die Messung, Berech-nung und Analyse eines hochpräzisen astrogeodätischen Quasigeoidprofils zur Validierung des gravimetrisc...

The objective of this paper is to give an insight into the near-field effect with respect to the coordinate domain. With the aid of Hannover's Automated Absolute Antenna Field Calibration Technique developed by the Institut fur Erdmessung (Universität Hannover) and Geo++® we demonstrate that mechanical structures mounted underneath the antennas (e....

This paper deals with the determination of a high-precision astrogeodetic quasigeoid profile for the validation of the gravimetric quasigeoid model GCG05 in the Harz mountains in Northern Germany. The Hannover Digital Zenith Camera System TZK2-D was used for the observation of new vertical deflection data at densely spaced stations (500-600 m avera...

During the last years the observation of vertical deflections experienced a revival due to the development of state-of-the-art Digital Zenith Camera Systems in Zurich and Hanover. Other than analogue instruments of geodetic astronomy, the new digital observation Systems provide vertical deflection data very fast and highly-accurate. One main applic...

The increasing resolution of ground based gravity measurements (e.g. by superconducting gravimeters) as well as satellite based gravity field studies allows to study very small signals, globally as well as local. On the other hand, this requires the correction of such signals to uncover others. To study the Earth’s deep interior and the on-going dy...

Within the framework of the European GOCE mission, which is scheduled for launch in 2007 by the European Space Agency (ESA), a high accuracy Satellite-to-Satellite Tracking Instrument (SSTI) with two hemispherical-coverage receiving antennas will be used for real time navigation and precise orbit determination. The two GPS antennas are directly mou...

The response of the Earth’s crust to the direct effect of lunisolar gravitational forcing is known as the body tide. The body tide is superimposed by surface-loading forces due to the pressure of the periodically varying ocean tide acting on the Earth, called ocean tide loading (OTL). Both body tide and OTL can be decomposed into components of the...

Antarctic GPS data from more than 20 stations were reanalyzed using the Bernese GPS Software, version 4.2, to provide a regional densification solution for the International Terrestrial Reference Frame (ITRF) 2000. In addition to the ITRF Antarctic results, two regional solutions with different strategies of the geodetic datum realization are analy...

The establishment and maintenance of geodetic reference frames which are an essential foundation for all surveys related to land management, GIS and large scale mapping are very expensive. Large countries like Brazil cannot afford a dense, nation-wide control network. Active GPS reference stations provide an alternative concept for reference frames...

Mit der Verfügbarkeit von CCD-Sensoren zur digitalen Bild-erfassung hat sich ein durchgreifender Wandel in der astronomischen Beobachtungstechnik vollzogen. Im Bereich der geodätischen Astronomie ist es dadurch in jüngster Zeit mög-lich geworden, die Messdatenerfassung zu automatisieren und astrogeodätische Lotrichtungsbestimmungen praktisch in Ech...

Mayon volcano is part of the Bicol volcanic chain on the island Luzon, Philippines. During this century there were ten activity periods distributed almost regularly. Because of the density of population (about one million people living in the vicinity of the volcano) three seismological observatories are in operation.Measurements of gravity changes...

 Scientific Committee on Antarctic Research (SCAR) The GPS campaigns of the between 1995 and 1998 provide a valuable data set which is used to link Antarctica with the ITRF (International Terrestrial Reference Frame), and to gain the first detailed insights into the tectonic behaviour of the Antarctic plate. The data analysis is based on seven indi...

On 3 February 1996, a magnitude 7.0 earthquake took place at Lijiang, Yunnan Province of southwest China. An intermediate-term earthquake prediction for the Jianchuan-Lijiang fault was issued in 1993 in which the magnitude, epicenter and occurrence time of the forthcoming earthquake were approximately given. This earthquake prediction was based on...

Geodetic measurements with the Global Positioning System (GPS) were performed in Northern Iceland between 1987 and 1995 in four consecutive surveys. The major goal was to monitor crustal deformations following a massive dyke intrusion episode which occurred between 1975 and 1985 in the Krafla volcanic system. Deformation analysis of the GPS surveys...

The SCAR 95 Epoch GPS Campaign was carried out from January 20 to February 10, 1995. A group of German scientists participated in the field work and data analysis in the frame of a "Geodetic Antarctic Project" (GAP). The data of 24 Antarctic, 5 additional stations, and 12 IGS stations were included in the analysis. The combined final solution was d...

ABSTRACT The electromagnetic ,behavior ,of antennas ,is not homogeneous.,The so-called phase center variations (PCV) describe the signal reception of GPS antennas and have been an important field of interest for the GPS community ,during the last years and still are. It remains as a main goal to improve antenna calibration

In order to estimate the characteristics of GPS antennas this paper describes a new approach for the estimation of absolute phase center variations (PCV) in a field calibration. The main objective of this approach is the elimination of multipath from the GPS observable and the elimination of any influence of the reference antenna. This is achieved...

During the XXIII Meeting of the Scientific Committee on Antarctic Research (SCAR) held in Rome in 1994 the Working Group on Geodesy and Geographic Information (SCAR WG-GGI) established a working program for the next two years. It was decided that SCAR Epoch GPS Campaigns should be organized as a continuation of former Epoch Campaigns.

The paper introduces a new approach to determine azimuth and elevation dependent phase center biases through a field measurement in an absolute sense. It takes special care of the multipath effects. The model, the conditions for the field procedure and preliminary analysis of results are presented. The absolute antenna phase center calibration proc...

Positioning with the NAVSTAR Global Positioning System, together with a detailed geoid model, can be used for a precise height transfer over larger distances at sea. The Helgoland tide gauge established already in 1880 and located in the open sea, has a special significance for mean sea level investigations in the area of the German Bay. Unfortunat...

The Helgoland tide gauge established already in 1880 and located in the open sea, has a special significance for mean sea level investigations in the area of the German Bay. Unfortunately, the present height connection to the tide gauges on the German mainland has an error of about 30 cm, which disturbs a common interpretation of mean sea level rec...

Precise DGPS Positioning (PDGPS) is required in a wide range of applications, but ambiguity resolution can still be problematic in a kinematic environment. Pure single frequency processing is limited by the ionosphere to distances up to 15 km and cannot benefit from the use of carrier phase linear combinations. The recent progress in receiver hardw...

In many of today’s precise GPS applications it is required to obtain the coordinate results in real-time. This is in particular true for marine and airborne applications, as well as for the control of land based vehicles and machines and for modern developments in cadaster and GIS surveying. Key factor is the rapid and reliable solution of ambiguit...

Two different types of differential global positioning systems (DGPS) are used for precise positioning and navigation. The “ordinary”; DGPS combines range corrections from a reference station with carrier smoothed pseudoranges at the moving station. This method works on a routine basis and provides accuracies of down to I m or even less. The precis...

Significant crustal movements, both horizontal and vertical, have been detected in Iceland using GPS. A GPS network extending across the axial rifting zone in Northern Iceland was measured twice, in 1987 and 1990. The network covers an area 200×300 km and contains 55 points common to both surveys. The coordinate differences have standard deviations...

INTERACTION of the elastic lithosphere with the underlying anelastic asthenosphere causes strain to propagate along the Earth's surface in a diffusion-like manner following tectonism at plate boundaries. This process transfers stress between adjacent tectonic segments and influences the temporal tectonic pattern along a plate boundary. Observations...

GPS has been developed in recent years to be a powerful means for the determination of precise coordinate differences. It can thus be used for monitoring local and regional crustal motions through repeated observations.

Iceland lies on the mid — Atlantic ridge at a latitude where the full spreading rate is 2.2 cm / year, which was estimated from seafloor anomalies south of Iceland (Talwani and Eldholm, 1977). The ridge on land is comprised of transform zones and the so-called neovolcanic zone that is made up of numerous volcanic systems. The first geodetic measure...

Contents: 1. Einleitung: Gegenstand der Satellitengeodäsie. 2. Allgemeine Grundlagen: Bezugssysteme. Zeit. Signalausbreitung. 3. Satellitenbewegung: Grundzüge der Himmelsmechanik, Zweikörperproblem. Gestörte Satellitenbewegung. Bahnbestimmung. Satellitenbahnen und Satellitenbahnmanöver. 4. Beobachtungskonzepte und geodätisch nutzbare Satelliten: Sa...

This is a short version of the paper giving the essential remarks and findings. The use of carrier smoothed pseudoranges in relative mode is demonstrated with the operational software package GNAV/GNAVC.

Within this report a short review on the performance of the DÖNAV field campaign, the scientific aims of the project and the present status of the data evaluation are given.

The satellite positioning systems, NNSS or Transit system and NAVSTAR-GPS, are used successfully for the determination of ice motion. The ice motion is derived from the change in the coordinates of a station between at least two measurement epochs. Simultaneous satellite observations on solid-ground-based and on ice stations yield precise relative...

The satellite positioning systems, NNSS or Transit system and NAVSTAR-GPS, are used successfully for the determination of ice motion. The ice motion is derived from the change in the coordinates of a station between at least two measurement epochs. Simultaneous satellite observations on solid-ground-based and on ice stations yield precise relative...

Based on two years of practical experiences in GPS research for marine applications, some findings and experiences are communicated. Research at the Institut für Erdmessung includes software developments,experiments under controlled conditions and practical applications. TI4100 receivers were used in single and differential mode. Software developme...

Within the marine geodetic research center at the Technical University Hannover there is one project that deals with methods for precise marine positioning, including satellite Doppler techniques. In 1977 a Doppler measuring campaign of eight weeks was performed for the precise positioning of the German research rig FPN in the North Sea. The result...

The new Zeiss-PK 1 Precision Comparator has been used by the Institut fur Theoretische Geodasie, Universitat Hannover since spring 1977. The instrument is mainly used for the measurement of plates from the transportable zenith camera TZK 1. In addition some experiences were gained with astrometric plates of a Schmidt telescope, a Ballistic Satellit...

In spite of refinements made in astronomical instruments during the last century, an area which has been neglected is the development of a truly reliable method for determining one's position on earth with respect to the stars. A portable device which can lock on to a star at zenith is described in terms of its design and operating parameters. A ph...

The Zenith camera system considered is currently being developed at the Institute for Theoretical Geodesy of the Technical University of Hannover, West Germany. The photographic camera employed has a focal length of 80 cm. A quartz clock with an accuracy of 1 msec is used for the recording of the exposure time. The camera is mounted on a turning ci...

The Technical University of Hanover has established a research center for the study of geodetic measuring techniques in coastal and marine regions. This paper describes the centers project for the determination of geoid. A transportable photographic zenith tube, developed to determine the direction of the gravity vector, is described.

[Ausz.] Bonn, Landwirtsch. F., Diss., 1972 (Nicht f. d. Aust.).

Die Geodäsie beschäftigt sich seit mehr als 3000 Jahren mit der Bestimmung der Erdfigur, wobei sich die Betrachtungsweise auf die Erde als Ganzes oder auf Teile von ihr erstreckt, das heißt, diese reicht vom besseren Verständnis globaler dynamischer Prozesse bis hin zu ingenieur-geodätischen Überwachungsmessungen. Die Messverfahren unterliegen eine...

The various educational programmes and projects implemented between Brazil and Germany are analysed with respect to strategies to attain sustainable results. Therefore, while minor stress is laid on the description of the particular programmes in contrast to focus on elements from which long-term success emerges.