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Spectral analysis of Borowiec SLR data for spin determination of geodetic satellite EGP

Kucharski D., Schillak S., Lim H. C., Otsubo T.

Artificial Satellites : Journal of Planetary Geodesy

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2013

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Vol. 48, No. 1

15--23

EN

Borowiec 10 Hz Satellite Laser Ranging (SLR) station is capable to measure spin of the Japanese Experimental Geodetic Satellite (EGP). Spectral analysis of 391 passes measured from March 10, 1994 to November 27, 2009 gives frequency signal representing the 3rd and the 6th harmonics of the satellite spin rate. Analysis of this signal, corrected for the apparent effects, indicates en exponential slowing down of the satellite: the spin rate decreases according to the equation f = 671.115907 exp(-4.08324 x 10-5 D) [mHz], where D is a day after launch. More than 15 years of the SLR measurements allowed investigating the initial spin rate of the satellite fini = 671.116, RMS = 0.203 [mHz] (initial spin period Tini = 1.49006, RMS = 0.0007 [s]).

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Introduction to joint analysis of SLR and GNSS data

Szafranek K., Schillak S.

Reports on Geodesy

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2012

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z. 1/92

143--154

EN

The paper presents models, parameters and assumptions concerning Satellite Laser Ranging (SLR) and Global Navigation Satellite System (GNSS) data processing, which will be conducted in the frame of a project concerning comparison of the site coordinates determined using these two techniques. The analysis will be performed by two research units: the Space Research Center (Polish Academy of Science) and the Center of Applied Geomatics (Military University of Technology) and will take into account the data from all global stations adopting SLR and GNSS techniques that were operating in the same time (from 1996 to 2011). The main goal is to obtain exact coordinates and their changes in time (velocities) on the basis of both techniques and to compare the results. The stations’ coordinates will be determined for the common reference epoch - for the first day of each month. According to the recommendations of the Global Geodetic Observing System (GGOS), the same models and parameters from IERS Conventions 2010 will be used in both processing strategies (if possible). Monthly orbital arcs for laser observations will be created on the basis of solutions from several SLR sites providing best quality results and the highest number of observations. For GNSS coordinates determination of about 100 sites belonging to International GNSS Service (IGS) will be selected: 30 with local ties to SLR sites and others chosen on the basis of their localization and quality of time series.

3

Determination of the SLR stations coordinates in 1994-2008

Schillak S.

Reports on Geodesy

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2012

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z. 1/92

227-236

EN

The paper presents results of the determination of SLR stations coordinates from the observations of LAGEOS-1 and LAGEOS-2 satellites for 5 years spans from 1994 until 2008. The computations of the station positions were performed by NASA Goddard’s GEODYN-II orbital program with a new models and parameters. The main purpose of this work is estimation of the SLR station position accuracy and its stability in the long time period. The accuracy is presented in the form of the station position stability, range biases and RMS of fit per station. The best results are for the span 1999-2003. In 2004-2008 the results show deterioration in the position accuracy of the several important stations. This effect can be explained by smaller number of normal points for some stations and jumps in the vertical component.

4

Time transfer realized by PPP technique for TRIMBLE NetRS and TTS-4 receivers

Lejba P., Nawrocki J., Schillak S., Lemański D., Lehmann M., Nogaś P.

Artificial Satellites : Journal of Planetary Geodesy

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2011

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Vol. 46, No. 4

151--163

EN

This paper concerns determination of clock readings and position of two geodetic receivers: TRIMBLE NetRS and TTS-4, connected to the same antenna of Dorne Margolin choke ring type (IGS BOR1 point) with the usage of precise point positioning (PPP) technique. The TTS-4 receiver was constructed and provided with its software by the time and frequency team from Borowiec Astrogeodynamical Observatory (AOS). Parameters of the receiver clocks and antenna coordinates were determined for the period from 1 to 30 April 2011. The collected data in RINEX format include code and phase observations from GPS constellation recorded with 30 second interval. The computed positions of the antenna based on RINEX data files from TRIMBLE NetRS and TTS-4 receivers are practically the same. The differences of estimated coordinates are from 0.6 to 1.6 mm. However, the accuracy of the clock parameters computed for TRIMBLE NetRS receiver are by one order lower than for TTS-4. It means that TRIMBLE NetRS receiver synchronized with internal quartz oscillator can not be used for timing applications. Currently the AOS laboratory works on the realization and development of the PPP method are in progress. Ultimately, the method will allow very precise comparison of atomic clocks and atomic time scales over great distances based on GNSS phase measurements. This method will increase the quality of comparisons of the atomic time scales carried out in the world, as well as, significantly strengthen the quality of the Polish Atomic Time Scale - TA (PL).

5

International SLR service

Schillak S.

Artificial Satellites : Journal of Planetary Geodesy

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2011

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Vol. 46, No. 4

119--126

EN

The paper presents the current state of the International Laser Ranging Service (ILRS): distribution of the SLR stations, data centers, analysis centers. The paper includes also the information about the last International Workshop on Laser Ranging in Bad Koetzting, 16-20 May, 2011. The problems of quality of the SLR data are presented. The list of parameters which can be used for estimation of the accuracy of the SLR data for each station is given. Results of determination of the station position stabilities over long term period (from 1994 up to 2008) for the selected few main stations are presented in the five years blocks. The results show slight deterioration of accuracy observed for the last several years and the reasons for this effect are indicated.

6

Wyznaczanie współrzędnych i prędkości stacji na podstawie obserwacji laserowych niskich satelitów

Lejba P., Schillak S.

Biuletyn Wojskowej Akademii Technicznej

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2010

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Vol. 59, nr 2

27-69

PL

W pracy przedstawiono wyniki wyznaczania orbit trzech niskich satelitów Ajisai, Starlette i Stella na podstawie obserwacji laserowych 14 stacji SLR wykonanych w latach 2001-2005. Ponadto wyznaczono geocentryczne i topocentryczne współrzędne oraz prędkości w płaszczyźnie horyzontu i przestrzeni 3D czterech stacji Yarragadee (7090), Greenbelt (7105), Graz (7839) i Herstmonceux (7840). Otrzymane wyniki porównano z wynikami otrzymanymi dla satelitów LAGEOS, układu ITRF2005 oraz dla modelu geologicznego NNR-NUVEL1A. Wszystkie obliczenia przeprowadzono w oparciu o model pola grawitacyjnego Ziemi EIGEN-GRACE02S. Przedstawione rezultaty pokazują, że wyniki obserwacji laserowych niskich satelitów takich jak Ajisai, Starlette, Stella mogą być z powodzeniem wykorzystane do wyznaczania współrzędnych i prędkości stacji SLR.

EN

In this work, the results of satellites orbit determination of three low satellites Ajisai, Starlette, and Stella on the laser observations of 14 SLR stations performed in the years 2001-2005 were presented. The geocentric and topocentric positions and velocities in horizontal plane and in 3-D space of four stations Yarragadee (7090), Greenbelt (7105), Graz (7839), and Herstmonceux (7840) were determined. The received results were compared with the results obtained for LAGEOS and with the ITRF2005 and the geological model NNR-NUVEL1A. All calculations have been made assuming the model of the Earth gravity field EIGEN-GRACE02S. The results presented in this work show that the laser data of low satellites such as Ajisai, Starlette or Stella can be successfully applied for determination of the SLR station positions and velocities.

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Porównanie wyników wyznaczania współrzędnych technikami GPS i SLR

Schillak S., Lehmann M.

Biuletyn Wojskowej Akademii Technicznej

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2010

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Vol. 59, nr 2

117-134

PL

Przedstawiono wyniki porównania współrzędnych stacji dla dwóch technik satelitarnych: laserowej i GPS. Współrzędne były wyznaczane dla wspólnych momentów w układzie współrzędnych ITRF2005. Porównanie wykonano dla wszystkich stacji wyposażonych w systemy SLR i GPS w okresie jedenastu lat od 1993.0 do 2004.0 bez uwzględnienia stacji laserowych, które zmieniły system w tym czasie. W sumie obliczenia wykonano dla 12 stacji. Współrzędne zostały obliczone dla okresów miesięcznych dla pierwszego dnia każdego miesiąca. Analiza wyników obejmowała ocenę stabilności pozycji stacji, różnice z ITRF2005, porównanie prędkości stacji dla obu technik. Prędkości porównano także z modelem ruchu płyt tektonicznych NNR-NUVEL1A i ITRF2005. Stwierdzono dobrą zgodność pozycji i prędkości stacji dla obu technik. Dla kilku stacji występują znaczne (1-3 cm) różnice w składowej pionowej.

EN

The paper presents results of the comparison of the station positions and velocities between two satellite techniques: Satellite Laser Ranging (SLR) and Global Positioning System (GPS). The coordinates were calculated for common epochs in the International Terrestrial Reference Frame 2005. The comparisons were performed for all stations equipped with the SLR and GPS systems in the period of time from 1993.0 to 2004.0 without SLR stations which changed the system in that time. Finally, calculations were performed for 12 stations. The coordinates were determined for epochs in the first day of each month. The analysis included estimation of the station positions stability, comparison with ITRF2005, station velocities comparison between both techniques. The tectonic plates model NNR-NUVEL1A and ITRF2005 velocities were used for verification of station velocities. Generally, with some exceptions, is a good agreement of the station positions and velocities between results for both techniques. For several stations, significant (1-3 cm) differences between vertical components were detected.