scholarly journals Erratum to: Determination of a terrestrial reference frame via Kalman filtering of very long baseline interferometry data

2016 ◽  
Vol 90 (12) ◽  
pp. 1329-1329 ◽  
Author(s):  
Benedikt Soja ◽  
Tobias Nilsson ◽  
Kyriakos Balidakis ◽  
Susanne Glaser ◽  
Robert Heinkelmann ◽  
...  
Keyword(s):  
Reference Frame ◽  
Kalman Filtering ◽  
Very Long Baseline Interferometry ◽  
Terrestrial Reference Frame ◽  
Long Baseline

scholarly journals Determination of a terrestrial reference frame via Kalman filtering of very long baseline interferometry data

2016 ◽  
Vol 90 (12) ◽  
pp. 1311-1327 ◽  
Author(s):  
Benedikt Soja ◽  
Tobias Nilsson ◽  
Kyriakos Balidakis ◽  
Susanne Glaser ◽  
Robert Heinkelmann ◽  
...  
Keyword(s):  
Reference Frame ◽  
Kalman Filtering ◽  
Very Long Baseline Interferometry ◽  
Terrestrial Reference Frame ◽  
Long Baseline

Where - A Software for geodetic Analysis

2020 ◽  
Author(s):  
Ingrid Fausk ◽  
Michael Dähnn ◽  
Ann-Silje Kirkvik
Keyword(s):  
Reference Frame ◽  
Software Package ◽  
Very Long Baseline Interferometry ◽  
Terrestrial Reference Frame ◽  
Test Phase ◽  
Laser Ranging ◽  
Operational Analysis ◽  
Long Baseline ◽  
Analysis Center ◽  
To Receive

<p><em>Where</em> is a software package developed by the Norwegian Mapping Authority (NMA). The software will provide a useful contribution to the International Terrestrial Reference Frame, by analysis of data from Very-long-baseline Interferometry (VLBI) and Satellite Laser Ranging (SLR).</p><div><em>Where</em> is written in Python, and is taking advantage of well-tested code like the SOFA and IERS libraries. The architecture is easily maintainable and extendable. Python makes it easy to write, and utilizes external libraries written in faster languages.</div><div> </div><div>Both the NMA and the Instituto Geografico Nacional, Spain, are in a test phase of deliveries of VLBI analysis results to the IVS with the <em>Where</em> software. After some improvements of the software, we will also deliver analysis results to the ILRS. Our goal is to receive full status as operational analysis center for both VLBI and SLR, and to contribute to ITRF2020.</div><div> </div><div>Sharing and cooperating with other institutions is made possible by making <em>Where</em> an open source project on GitHub.</div>

scholarly journals Scheduling And Simulation Of VLBI Measurements For The Determination Of Earth Orientation Parameters

2015 ◽  
Vol 5 (1) ◽  
pp. 61-68 ◽  
Author(s):  
S. Nistor ◽  
A. S. Buda
Keyword(s):  
Very Long Baseline Interferometry ◽  
Terrestrial Reference Frame ◽  
Point Of View ◽  
Earth Orientation Parameters ◽  
Earth Orientation ◽  
Long Baseline ◽  
Celestial Sphere ◽  
Orientation Parameters ◽  
Primary Space

Abstract The article aims to present the results obtain from the scheduling and simulation of VLBI measurements in October 2010 for a period of three days for 24 hour continuous observations. To be sure that we will obtain good VLBI observation we have to do an optimization of the network. This can be done quite accurately by using the new modules that are part of the VLBI processing software’s, the modules scheduling and simulation. This can be considered the first step in preparation of the VLBI experiment. Very Long Baseline Interferometry (VLBI) it is a primary space-geodetic technique that it is able to determine precise coordinates on the Earth, by monitoring the variable of Earth orientation parameters (EOP) with high precision. Also Very Long Baseline Interferometry plays an important role for determination of celestial and terrestrial reference frame. It is also a technique that each year is more developed form a software and hardware point of view. To obtain the scans we used a set of eight different VLBI antennas and as a source we used different quasars. In the scheduling we used the source based strategy contrary to the station based approach and the radio sources where from updated catalogues according to the requirements of the VLBI2010 system, which means that we are able to obtain a best coverage of the celestial sphere. The results show that scheduling and simulation are very good tools in preparing real VLBI experiments.

scholarly journals Commision 19: Earth Rotation (Rotation de la Terre)

1991 ◽  
Vol 21 (1) ◽  
pp. 169-186
Keyword(s):  
Reference Frame ◽  
Earth Rotation ◽  
Very Long Baseline Interferometry ◽  
International Association ◽  
High Accuracy ◽  
Terrestrial Reference Frame ◽  
International Earth Rotation Service ◽  
Long Baseline ◽  
Compact Sources ◽  
Celestial Reference Frame

The period has been marked by the start of the new International Earth Rotation Service (IERS), which benefits from a tight cooperation between astronomers, geodesists, and specialists in satellite geodesy, as well as meteorologists. The scope of the IERS covers not only the Earth’s rotation per se, but also the conventional terrestrial reference frame, of direct interest to the International Association of Geodesy, and a high accuracy (0.001”) celestial reference frame based on extragalactic compact sources observed in Very Long Baseline Interferometry. The IERS conventional celestial reference frame is consistent with the FK5 within the uncertainties of the latter (0.04”). The IERS Standards (1989) which contain the current best estimates of astronomical models and constants are used in many fields of astronomy and geodesy.

scholarly journals Testing impact of the strategy of VLBI data analysis on the estimation of Earth Orientation Parameters and station coordinates

2016 ◽  
Vol 101 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Agata Wielgosz ◽  
Monika Tercjak ◽  
Aleksander Brzeziński
Keyword(s):  
Reference Frame ◽  
Terrestrial Reference Frame ◽  
Earth Orientation Parameters ◽  
Earth Orientation ◽  
Long Baseline ◽  
Station Coordinates ◽  
Vlbi Data ◽  
Weighting Strategy ◽  
Orientation Parameters

Abstract Very Long Baseline Interferometry (VLBI) is the only space geodetic technique capable to realise the Celestial Reference Frame and tie it with the Terrestrial Reference Frame. It is also the only technique, which measures all the Earth Orientation Parameters (EOP) on a regular basis, thus the role of VLBI in determination of the universal time, nutation and polar motion and station coordinates is invaluable. Although geodetic VLBI has been providing observations for more than 30 years, there are no clear guidelines how to deal with the stations or baselines having significantly bigger post-fit residuals than the other ones. In our work we compare the common weighting strategy, using squared formal errors, with strategies involving exclusion or down-weighting of stations or baselines. For that purpose we apply the Vienna VLBI Software VieVS with necessary additional procedures. In our analysis we focus on statistical indicators that might be the criterion of excluding or down-weighting the inferior stations or baselines, as well as on the influence of adopted strategy on the EOP and station coordinates estimation. Our analysis shows that in about 99% of 24-hour VLBI sessions there is no need to exclude any data as the down-weighting procedure is sufficiently efficient. Although results presented here do not clearly indicate the best algorithm, they show strengths and weaknesses of the applied methods and point some limitations of automatic analysis of VLBI data. Moreover, it is also shown that the influence of the adopted weighting strategy is not always clearly reflected in the results of analysis.

The Contribution of LARES to Global Climate Change Studies With Geodetic Satellites

2015 ◽  
Author(s):  
Giampiero Sindoni ◽  
Claudio Paris ◽  
Cristian Vendittozzi ◽  
Erricos C. Pavlis ◽  
Ignazio Ciufolini ◽  
...  
Keyword(s):  
Reference Frame ◽  
Earth Science ◽  
Global Climate ◽  
Temporal Variations ◽  
Terrestrial Reference Frame ◽  
Global Navigation Satellite Systems ◽  
Satellite Systems ◽  
Long Baseline ◽  
Geophysical Processes ◽  
Global Navigation Satellite

Satellite Laser Ranging (SLR) makes an important contribution to Earth science providing the most accurate measurement of the long-wavelength components of Earth’s gravity field, including their temporal variations. Furthermore, SLR data along with those from the other three geometric space techniques, Very Long Baseline Interferometry (VLBI), Global Navigation Satellite Systems (GNSS) and DORIS, generate and maintain the International Terrestrial Reference Frame (ITRF) that is used as a reference by all Earth Observing systems and beyond. As a result we obtain accurate station positions and linear velocities, a manifestation of tectonic plate movements important in earthquake studies and in geophysics in general. The “geodetic” satellites used in SLR are passive spheres characterized by very high density, with little else than gravity perturbing their orbits. As a result they define a very stable reference frame, defining primarily and uniquely the origin of the ITRF, and in equal shares, its scale. The ITRF is indeed used as “the” standard to which we can compare regional, GNSS-derived and alternate frames. The melting of global icecaps, ocean and atmospheric circulation, sea-level change, hydrological and internal Earth-mass redistribution are nowadays monitored using satellites. The observations and products of these missions are geolocated and referenced using the ITRF. This allows scientists to splice together records from various missions sometimes several years apart, to generate useful records for monitoring geophysical processes over several decades. The exchange of angular momentum between the atmosphere and solid Earth for example is measured and can be exploited for monitoring global change. LARES, an Italian Space Agency (ASI) satellite, is the latest geodetic satellite placed in orbit. Its main contribution is in the area of geodesy and the definition of the ITRF in particular and this presentation will discuss the improvements it will make in the aforementioned areas.

scholarly journals The Celestial Frame and the Weighting of the Celestial Pole Offsets in the Computation of VLBI-Based Corrections for the Main Lunisolar Nutation Terms

Sensors ◽  
2021 ◽  
Vol 21 (24) ◽  
pp. 8276
Author(s):  
Víctor Puente ◽  
Marta Folgueira
Keyword(s):  
Stochastic Model ◽  
Least Squares ◽  
Reference Frame ◽  
Very Long Baseline Interferometry ◽  
Long Baseline ◽  
Celestial Pole ◽  
Two Factors ◽  
Least Squares Adjustment ◽  
Empirical Corrections ◽  
Celestial Reference Frame

Very long baseline interferometry (VLBI) is the only technique in space geodesy that can determine directly the celestial pole offsets (CPO). In this paper, we make use of the CPO derived from global VLBI solutions to estimate empirical corrections to the main lunisolar nutation terms included in the IAU 2006/2000A precession–nutation model. In particular, we pay attention to two factors that affect the estimation of such corrections: the celestial reference frame used in the production of the global VLBI solutions and the stochastic model employed in the least-squares adjustment of the corrections. In both cases, we have found that the choice of these aspects has an effect of a few μas in the estimated corrections.

Determination of Position of Jupiter From Very-Long Baseline Interferometry Observations of ULYSSES

1996 ◽  
Vol 112 ◽  
pp. 1294 ◽  
Author(s):  
W. M. Folkner ◽  
T. P. McElrath ◽  
A. J. Mannucci
Keyword(s):  
Very Long Baseline Interferometry ◽  
Long Baseline

scholarly journals VLBI studies of the nutations of the earth

1988 ◽  
Vol 129 ◽  
pp. 371-375
Author(s):  
T. A. Herring
Keyword(s):  
Truncation Error ◽  
Very Long Baseline Interferometry ◽  
Long Baseline ◽  
The Earth ◽  
Vlbi Data ◽  
One Year ◽  
Nutation Series ◽  
Theoretical Considerations ◽  
Active Investigation

The application of very–long–baseline interferometry (VLBI) to the study of the nutations of the earth has yielded unprecedented accuracy for the experimental determination of the coefficients of the nutation series. The analysis of six years of VLBI data has yielded corrections to the coefficients of the seven largest terms in the IAU 1980 nutation series with periods of one year or less, with accuracies approaching the truncation error of this nutation series (0.1 mas). The nutation series coefficients computed from the VLBI data, and those obtained from theoretical considerations (the IAU 1980 nutation series), are in excellent agreement. The largest corrections are to the coefficients of the retrograde annual nutation [2.0 ± 0.1 mas], the prograde semiannual nutation [(0.5 - ι 0.4) ±0.1 mas], and the prograde 13.7 day nutation [−0.4 ± 0.1 mas]. (The imaginary term for the semiannual nutation represents a term 90° out–of–phase with the arguments of the nutation series.) The geophysical implications of these results are currently under active investigation. We discuss the methods used to extract the nutation information from the VLBI data, the calculations of the uncertainties of the resultant corrections to the coefficients of the nutation series, and the current research into the nutations of the earth.

scholarly journals Geocentric Terrestrial Reference Frame Accuracy: DSN Spacecraft Tracking and VLBI/Lunar Laser Ranging

1988 ◽  
Vol 128 ◽  
pp. 115-120 ◽  
Author(s):  
A. E. Niell
Keyword(s):  
Reference Frame ◽  
Terrestrial Reference Frame ◽  
Spin Axis ◽  
Laser Ranging ◽  
Lunar Laser Ranging ◽  
Deep Space Network ◽  
Long Baseline ◽  
Lunar Laser ◽  
Spacecraft Tracking ◽  
Geocentric Coordinates

From a combination of 1) the location of McDonald Observatory from Lunar Laser Ranging, 2) relative station locations obtained from Very Long Baseline Interferometry (VLBI) measurements, and 3) a short tie by traditional geodesy, the geocentric coordinates of the 64 m antennas of the NASA/JPL Deep Space Network are obtained with an orientation which is related to the planetary ephemerides and to the celestial radio reference frame. Comparison with the geocentric positions of the same antennas obtained from tracking of interplanetary spacecraft shows that the two methods agree to 20 cm in distance off the spin axis and in relative longitude. The orientation difference of a 1 meter rotation about the spin axis is consistent with the error introduced into the tracking station locations due to an error in the ephemeris of Jupiter.

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