Operating two SLR systems at the Geodetic Observatory Wettzell: from local survey to space ties

Riepl, Stefan; Müller, Hendrik; Mähler, S.; Eckl, Johann; Klügel, Thomas; Schreiber, Ulrich; Schüler, Torben

doi:10.1007/s00190-019-01243-z

Cited by 11 publications

(16 citation statements)

References 6 publications

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“…Co-location of Space Geodetic Techniques: Studies on Intra-Technique Short Baselines Figure 9 shows the single-difference residuals grouped by constellation, allowing for mis-synchronisation of 3 h (quasisimultaneity). This analysis reveals that the residuals are evidently biased, with a mean value of 26.3 mm, a value related to the range biases of WLRS and SOS-W. An extensive analysis of these biases is discussed in details in Riepl et al (2019). Not only range biases can be observed within these differences, but, after removing the mean bias, errors associated to the orbits are also noticeable (Fig.…”

Section: Differencing Approaches For Slr Short Baselinesmentioning

confidence: 88%

Co-location of Space Geodetic Techniques: Studies on Intra-Technique Short Baselines

Herrera-Pinzón

Rothacher

2020

International Association of Geodesy Symposia

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The goal of the project "Co-location of Space Geodetic Techniques on Ground and in Space", in the DFG funded research unit on reference systems and founded by the Swiss National Foundation (SNF), is the improvement of existing and the establishment of new ties between the space geodetic techniques, together with the assessment and reduction of technique-specific biases. To achieve this, the wealth of co-located instruments at the Geodetic Observatory Wettzell (Germany) are used, where systematic errors in the space geodetic techniques can be detected, assessed and removed on very short, well-known baselines. Within this paper we summarise results for three intra-technique co-location experiments in Wettzell. Firstly, an assessment of the GNSS to GNSS baselines in relation to the surveyed local ties shows discrepancies of up to 9 mm, for solutions based on the ionosphere-free linear combination. Secondly, an analysis of the short VLBI baseline shows that the use of a clock tie achieves a sub-mm agreement with respect to the local tie. And finally, initial results on the usage of differencing approaches on the short SLR baseline show that double-difference residuals are within˙4 mm. The results of this work show the potential of intra-technique studies on short baselines for the understanding of techniquespecific biases and errors and for the monitoring of local ties.

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Section: Differencing Approaches For Slr Short Baselinesmentioning

confidence: 88%

Co-location of Space Geodetic Techniques: Studies on Intra-Technique Short Baselines

Herrera-Pinzón

Rothacher

2020

International Association of Geodesy Symposia

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“…The SOS-W is the modern SLR laser telescope at GOW. It operates with a two-color laser for daytime and nighttime conditions to mainly reduce atmospheric refraction uncertainties [43]. The telescope is enclosed by a turnable protecting dome, comparable to a sphere with a diameter of about 5 m and the telescope in its center, cf.…”

Section: Measurements and Configurationsmentioning

confidence: 99%

ILRS Reference Point Determination Using Close Range Photogrammetry

et al. 2021

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A global geodetic reference system (GGRS) is realized by physical points on the Earth’s surface and is referred to as a global geodetic reference frame (GGRF). The GGRF is derived by combining several space geodetic techniques, and the reference points of these techniques are the physical points of such a realization. Due to the weak physical connection between the space geodetic techniques, so-called local ties are introduced to the combination procedure. A local tie is the spatial vector defined between the reference points of two space geodetic techniques. It is derivable by local measurements at multitechnique stations, which operate more than one space geodetic technique. Local ties are a crucial component within the intertechnique combination; therefore, erroneous or outdated vectors affect the global results. In order to reach the ambitious accuracy goal of 1 mm for a global position, the global geodetic observing system (GGOS) aims for strategies to improve local ties, and, thus, the reference point determination procedures. In this contribution, close range photogrammetry is applied for the first time to determine the reference point of a laser telescope used for satellite laser ranging (SLR) at Geodetic Observatory Wettzell (GOW). A measurement campaign using various configurations was performed at the Satellite Observing System Wettzell (SOS-W) to evaluate the achievable accuracy and the measurement effort. The bias of the estimates were studied using an unscented transformation. Biases occur if nonlinear functions are replaced and are solved by linear substitute problems. Moreover, the influence of the chosen stochastic model onto the estimates is studied by means of various dispersion matrices of the observations. It is shown that the resulting standard deviations are two to three times overestimated if stochastic dependencies are neglected.

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“…5 bottom). For station Graz, a recently discovered pressure bias occurred since 2015 (Pavlis and Kuźmicz-Cieślak 2020); thus, this station will be analyzed in detail in subsequent parts of the paper together with the station Wettzell, where also a bias was discovered which could not be attributed to any specific parts of the SLR system (Riepl et al 2019). Figure 5 shows that the mean TRP value only marginally changes when adding the estimation of RGB, which means that RGB corrections absorb the TRP offsets only to a minor extent.…”

Section: Analysis Of Range Biases and Trp Correction For Slr Stationsmentioning

confidence: 99%

“…For the Wettzell observatory, a discrepancy in meteorological data has been found between the Satellite Observing System Wettzell (SOS-W, 7827) and the Wettzell Laser Ranging System (WLRS, 8834) (Riepl et al 2019;Pavlis and Kuźmicz-Cieślak 2020). Figure 7 shows a prominent negative secular rate of the TRP corrections, which substantially affect the vertical component of station coordinates in the STD solution in the form of large-scale positive drift.…”

Section: Analysis Of Range Biases and Trp Correction For Slr Stationsmentioning

confidence: 99%

Tropospheric and range biases in Satellite Laser Ranging

Drożdżewski

Sośnica

2021

J Geod

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The Satellite Laser Ranging (SLR) technique provides very accurate distance measurements to artificial Earth satellites. SLR is employed for the realization of the origin and the scale of the terrestrial reference frame. Despite the high precision, SLR observations can be affected by various systematic errors. So far, range biases were used to account for systematic measurement errors and mismodeling effects in SLR. Range biases are constant for all elevation angles and independent of the measured distance to a satellite. Recently, intensity-dependent biases for single-photon SLR detectors and offsets of barometer readings and meteorological devices were reported for some SLR stations. In this paper, we study the possibility of the direct estimation of tropospheric biases from SLR observations to LAGEOS satellites. We discuss the correlations between the station heights, range biases, tropospheric biases, and their impact on the repeatability of station coordinates, geocenter motion, and the global scale of the reference frame. We found that the solution with the estimation of tropospheric biases provides more stable station coordinates than the solution with the estimation of range biases. From the common estimation of range and tropospheric biases, we found that most of the systematic effects at SLR stations are better absorbed by elevation-dependent tropospheric biases than range biases which overestimate the total bias effect. The estimation of tropospheric biases changes the SLR-derived global scale by 0.3 mm and the geocenter coordinates by 1 mm for the Z component, causing thus an offset in the realization of the reference frame origin. Estimation of range biases introduces an offset in some SLR-derived low-degree spherical harmonics of the Earth’s gravity field. Therefore, considering elevation-dependent tropospheric and intensity biases is essential for deriving high-accuracy geodetic parameters.

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Operating two SLR systems at the Geodetic Observatory Wettzell: from local survey to space ties

Cited by 11 publications

References 6 publications

Co-location of Space Geodetic Techniques: Studies on Intra-Technique Short Baselines

Co-location of Space Geodetic Techniques: Studies on Intra-Technique Short Baselines

ILRS Reference Point Determination Using Close Range Photogrammetry

Tropospheric and range biases in Satellite Laser Ranging

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