The Australian GPS Orbit Determination Pilot Project: A Status Report

The International Laser Ranging Service (ILRS) Analysis Standing Committee (ASC) plans to complete the re-analysis of the SLR data since 1983 to end of this year by early 2021. This will ensure that the ILRS contribution to ITRF2020 will be available to ITRS by February 2021, as agreed by all space geodetic techniques answering its call. In preparation for the development of this contribution, the ILRS completed the re-analysis of all data (1983 to present), based on an improved modeling of the data and a novel approach that ensures the results are free of systematic errors in the underlying data. The new approach was developed after the completion of ITRF2014, the ILRS ASC devoting almost entirely its efforts on this task. A Pilot Project initially demonstrated the robust estimation of persistent systematic errors at the millimeter level, leading us to adopt a consistent set of a priori corrections for data collected in past years. The initial reanalysis used these corrections, leading to improved results for the TRF attributes, reflected in the resulting new time series of the TRF origin and scale. The ILRS ASC will now use the new approach in the development of its operational products and as a tool to monitor station performance, extending the history of systematics for each system that will be used in future re-analysis. The new operational products form a seamless extension of the re-analysis series, providing a continuous product based on our best knowledge of the ground system behavior and performance, without any dependence whatsoever on a priori knowledge of systematic errors (although information provided by the stations from their own engineering investigations are always welcome and taken into consideration). The presentation will demonstrate the level of improvement with respect to the previous ILRS product series and give a glimpse of what is to be expected from the development of a preliminary version of the ITRF2020.

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KOMPSAT-2 Orbit Determination Status Report

AIAA/AAS Astrodynamics Specialist Conference ◽

10.2514/6.2010-8260 ◽

2010 ◽

Cited By ~ 1

Author(s):

Yoola Hwang ◽

Byoung-Sun Lee ◽

Jaehoon Kim ◽

Ok-Chul Jung ◽

Daewon Chung ◽

...

Keyword(s):

Orbit Determination ◽

Status Report

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Precise GLONASS orbit determination within the IGS/IGLOS – Pilot Project

Advances in Space Research ◽

10.1016/j.asr.2005.08.051 ◽

2005 ◽

Vol 36 (3) ◽

pp. 369-375 ◽

Cited By ~ 18

Author(s):

Robert Weber ◽

James A. Slater ◽

Elisabeth Fragner ◽

Vladimir Glotov ◽

Heinz Habrich ◽

...

Keyword(s):

Orbit Determination ◽

Pilot Project

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Establishing the California Department of Transportation Accelerated Pavement Testing Program

Transportation Research Record Journal of the Transportation Research Board ◽

10.1177/0361198196154000113 ◽

1996 ◽

Vol 1540 (1) ◽

pp. 91-96 ◽

Cited By ~ 1

Author(s):

W. A. Nokes ◽

P. J. Stolarski ◽

C. L. Monismith ◽

J. T. Harvey ◽

N. Coetzee ◽

...

Keyword(s):

Laboratory Tests ◽

Pilot Project ◽

Status Report ◽

Department Of Transportation ◽

California Department ◽

Accelerated Pavement Testing ◽

Testing Program ◽

Testing Technology ◽

History Of ◽

Pavement Testing

How the California Department of Transportation Accelerated Pavement Testing (CAL/APT) Program was established is described. Discussion includes history of the program, search for full-scale pavement testing technology suitable to California, results of a pilot project conducted on test pavements built in South Africa, laboratory tests included in the CAL/APT program, and development of an organization to manage CAL/APT and implement its products. A status report on testing and planning is included.

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Precise Galileo orbit determination using combined GNSS and SLR observations

10.5194/egusphere-egu2020-340 ◽

2020 ◽

Author(s):

Grzegorz Bury ◽

Krzysztof Sośnica ◽

Radosław Zajdel ◽

Dariusz Strugarek

Keyword(s):

Orbit Determination ◽

Reference Frames ◽

European Space Agency ◽

Pilot Project ◽

Laser Ranging ◽

Navigation Satellite ◽

International Gnss Service ◽

Terrestrial Reference Frames ◽

Gnss Data ◽

The Impact

The European navigation system Galileo is on its final stretch to become a fully operational capability (FOC) Global Navigation Satellite System (GNSS). The current constellation consists of 24 healthy satellites decomposed into three Medium Earth Orbits and since late 2016 is considered as an operational system. So far, the official Galileo orbits are provided by the European Space Agency and in the frame of the International GNSS Service (IGS) Multi-GNSS pilot project (MGEX) whose one of the goals is to develop orbit determination strategies for all new emerging navigation satellite systems.All the Galileo satellites are equipped with Laser Retroreflector Arrays (LRA) for Satellite Laser Ranging (SLR). As a result, a number of Galileo satellites is tracked by laser stations of the International Laser Ranging Service (ILRS). SLR measurements to GNSS, such as Galileo, comprise a valuable tool for the validation of the orbit products as well as for an independent orbit solution based solely on laser ranging data. However, the SLR data may be used together along with the GNSS observations for the determination of the combined GNSS orbit using the two independent space techniques co-located onboard the Galileo satellites. The Galileo orbit determination strategies, as well as the usage of laser ranging to the navigation satellites, is crucial, especially in the light of the discussion concerning possible usability of the Galileo observation in the future realizations of the International Terrestrial Reference Frames.&#160;&#160; &#160;In this study, we present results from the precise Galileo orbit determination using the combined GNSS data transmitted by the Galileo satellites and the range measurements performed by the ILRS stations. We test different weighting strategies for GNSS and SLR observations. We test the formal errors of the Keplerian elements which significantly decrease when we apply the same weights for SLR &#160;and GNSS data. However, in such a manner, we deteriorate the internal consistency of the solution, i.e., the orbit misclosures. &#160;For the solution with optimal weighting strategy, we present results of the quality of Galileo orbit predictions based on the combined solutions, as well as the SLR residuals. The combined GNSS+SLR solution seems to be especially favorable for the Galileo In-Orbit Validation (IOV) satellites, for which the standard deviation (STD) of the SLR residuals decreases by 13% as compared to the microwave solutions, whereas for the Galileo-FOC satellite the improvement of the STD of SLR residuals is at the level of 9%. Finally, we test the impact of adding SLR observations to the LAGEOS satellites which stabilizes the GNSS solutions, especially in terms of the realization of terrestrial reference frame origin.&#160;

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Progress in the compilation of the FK5

International Astronomical Union Colloquium ◽

10.1017/s0252921100074388 ◽

1978 ◽

Vol 48 ◽

pp. 421-432 ◽

Cited By ~ 7

Author(s):

W. Fricke ◽

W. Gliese

Keyword(s):

Status Report ◽

Magnitude Range

Abstract:Presented is a status report on work on FK5 giving information on the following items: (a) the intended increase of the number of fundamental stars and their magnitude range in FK5, (b) available material for the improvement of the system, (c) methods for the determination of systematic differences, (d) the determination of equator and equinox of FK5, and (e) the elimination of the motion of the FK4 equinox.

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Scanning tunneling microscopy of polymers: A status report

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100153622 ◽

1989 ◽

Vol 47 ◽

pp. 330-331

Author(s):

P.E. Russell ◽

I.H. Musselman

Keyword(s):

High Resolution ◽

Scanning Tunneling Microscopy ◽

Sample Surface ◽

Atomic Scale ◽

Constant Current ◽

Scanning Tunneling ◽

Status Report ◽

Tunneling Microscopy ◽

Research Issues ◽

Wide Range

Scanning tunneling microscopy (STM) has evolved rapidly in the past few years. Major developments have occurred in instrumentation, theory, and in a wide range of applications. In this paper, an overview of the application of STM and related techniques to polymers will be given, followed by a discussion of current research issues and prospects for future developments. The application of STM to polymers can be conveniently divided into the following subject areas: atomic scale imaging of uncoated polymer structures; topographic imaging and metrology of man-made polymer structures; and modification of polymer structures. Since many polymers are poor electrical conductors and hence unsuitable for use as a tunneling electrode, the related atomic force microscopy (AFM) technique which is capable of imaging both conductors and insulators has also been applied to polymers.The STM is well known for its high resolution capabilities in the x, y and z axes (Å in x andy and sub-Å in z). In addition to high resolution capabilities, the STM technique provides true three dimensional information in the constant current mode. In this mode, the STM tip is held at a fixed tunneling current (and a fixed bias voltage) and hence a fixed height above the sample surface while scanning across the sample surface.

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