On comparison of the Earth orientation parameters obtained from different VLBI networks and observing programs

Malkin, Zinovy

doi:10.1007/s00190-008-0265-2

Cited by 34 publications

(32 citation statements)

References 11 publications

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“…The volume of the spanned network correlates with the expected accuracy of measured Earth orientation parameters (Malkin 2009), and uneven antenna distribution makes the results prone to systematic errors (Böckmann et al 2010). Traditionally, the Northern Hemisphere is much more strongly represented than the Southern Hemisphere.…”

Section: Introductionmentioning

confidence: 97%

The AUSTRAL VLBI observing program

Plank

Lovell

McCallum

et al. 2016

J Geod

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The AUSTRAL observing program was started in 2011, performing geodetic and astrometric very long baseline interferometry (VLBI) sessions using the new Australian AuScope VLBI antennas at Hobart, Katherine, and Yarragadee, with contribution from the Warkworth (New Zealand) 12 m and Hartebeesthoek (South Africa) 15 m antennas to make a southern hemisphere array of telescopes with similar design and capability. Designed in the style of the nextgeneration VLBI system, these small and fast antennas allow for a new way of observing, comprising higher data rates and more observations than the standard observing sessions coordinated by the International VLBI Service for Geodesy and Astrometry (IVS). In this contribution, the continuous development of the AUSTRAL sessions is described, leading to an improvement of the results in terms of baseline length repeatabilities by a factor of two since the start of this program. The focus is on the scheduling strategy and increased number of observations, aspects of automated operation, and data logistics, as well as results of the 151 AUSTRAL sessions performed so far. The high number of the AUSTRAL

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Section: Introductionmentioning

confidence: 97%

The AUSTRAL VLBI observing program

Plank

Lovell

McCallum

et al. 2016

J Geod

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“…Although EOP estimates tend to be slightly worse than the results from reference solutions, the identified decrease in accuracy is rather small when comparing against the performance of actual VLBI sessions, especially in the case of UT1-UTC estimates. As stated by Malkin (2009), the precision of the latter parameter and pole coordinates, both derived based on the IVS-R1 sessions, amounts to 3 μs and 60 μas, respectively.…”

Section: Earth Orientation Parametersmentioning

confidence: 95%

Geodetic VLBI with an artificial radio source on the Moon: a simulation study

Kłopotek

Hobiger

Haas

2017

J Geod

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We perform extensive simulations in order to assess the accuracy with which the position of a radio transmitter on the surface of the Moon can be determined by geodetic VLBI. We study how the quality and quantity of geodetic VLBI observations influence these position estimates and investigate how observations of such near-field objects affect classical geodetic parameters like VLBI station coordinates and Earth rotation parameters. Our studies are based on today's global geodetic VLBI schedules as well as on those designed for the next-generation geodetic VLBI system. We use Monte Carlo simulations including realistic stochastic models of troposphere, station clocks, and observational noise. Our results indicate that it is possible to position a radio transmitter on the Moon using today's geodetic VLBI with a two-dimensional horizontal accuracy of better than one meter. Moreover, we show that the nextgeneration geodetic VLBI has the potential to improve the two-dimensional accuracy to better than 5 cm. Thus, our results lay the base for novel observing concepts to improve both lunar research and geodetic VLBI.

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“…For uniformly optimistic and Gaussian errors, the GSFC Ȥ 2 value is consistent with a smaller error rescaling factor of 1.61 assuming no common-mode VLBI errors shared by the two UT1 series. But Malkin (2009) has recently examined VLBI polar motion precision and accuracy, relative to the IGS multi-center estimates, and found inaccuracies for the most sensitive networks that are larger than the formal errors by 1.6 to 1.9 times. So we opt for a rescaling factor of 2.…”

Section: Input Data Setsmentioning

confidence: 99%

Status and Prospects for Combined GPS LOD and VLBI UT1 Measurements

Senior¹,

Kouba²,

Ray³

2010

Artificial Satellites

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ABSTRACT.A Kalman filter was developed to combine VLBI estimates of UT1-TAI with biased length of day (LOD) estimates from GPS. The VLBI results are the analyses of the NASA Goddard Space Flight Center group from 24-hr multi-station observing sessions several times per week and the nearly daily 1-hr single-baseline sessions. Daily GPS LOD estimates from the International GNSS Service (IGS) are combined with the VLBI UT1-TAI by modeling the natural excitation of LOD as the integral of a white noise process (i.e., as a random walk) and the UT1 variations as the integration of LOD, similar to the method described by Morabito et al. (1988). To account for GPS technique errors, which express themselves mostly as temporally correlated biases in the LOD measurements, a Gauss-Markov model has been added to assimilate the IGS data, together with a fortnightly sinusoidal term to capture errors in the IGS treatments of tidal effects. Evaluated against independent atmospheric and oceanic axial angular momentum (AAM + OAM) excitations and compared to other UT1/LOD combinations, ours performs best overall in terms of lowest RMS residual and highest correlation with (AAM + OAM) over sliding intervals down to 3 d. The IERS 05C04 and Bulletin A combinations show strong high-frequency smoothing and other problems. Until modified, the JPL SPACE series suffered in the high frequencies from not including any GPS-based LODs. We find, surprisingly, that further improvements are possible in the Kalman filter combination by selective rejection of some VLBI data. The best combined results are obtained by excluding all the 1-hr single-baseline UT1 data as well as those 24-hr UT1 measurements with formal errors greater than 5 μs (about 18% of the multi-baseline sessions). A rescaling of the VLBI formal errors, rather than rejection, was not an effective strategy. These results suggest that the UT1 errors of the 1-hr and weaker 24-hr VLBI sessions are non-Gaussian and more heterogeneous than expected, possibly due to the diversity of observing geometries used, other neglected 58 systematic effects, or to the much shorter observational averaging interval of the single-baseline sessions. UT1 prediction services could benefit from better handling of VLBI inputs together with proper assimilation of IGS LOD products, including using the Ultra-rapid series that is updated four times daily with 15 hr delay.

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On comparison of the Earth orientation parameters obtained from different VLBI networks and observing programs

Cited by 34 publications

References 11 publications

The AUSTRAL VLBI observing program

The AUSTRAL VLBI observing program

Geodetic VLBI with an artificial radio source on the Moon: a simulation study

Status and Prospects for Combined GPS LOD and VLBI UT1 Measurements

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