The International VLBI Service for Geodesy and Astrometry (IVS): current capabilities and future prospects

Schlüter, Wolfgang; Behrend, Dirk

doi:10.1007/s00190-006-0131-z

Cited by 137 publications

(71 citation statements)

References 4 publications

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“…Doing so, one avoids contaminating the estimated nutation offsets by radio source instabilities. All the calculations used the Calc 10.0/Solve 2008.12.05 geodetic VLBI analysis software package developped and maintained at NASA/Goddard Space Flight Center, and were carried out at the Paris Observatory IVS Analysis Center as part of the International VLBI Service for Geodesy and Astrometry (IVS, Schlüter & Behrend 2007).…”

Section: Nutationmentioning

confidence: 99%

Free core nutation resonance parameters from VLBI and superconducting gravimeter data

Rosat¹,

Lambert²

2009

A&A

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Context. Free core nutation (FCN) can be observed by its associated resonance effects on the forced nutations of the Earth's figure axis, as observed by very long baseline interferometry (VLBI), or on the diurnal tidal waves, retrieved from the time-varying surface gravity recorded by superconducting gravimeters (SG). Aims. In this paper, we study the sensitivity of both techniques to FCN parameters. Methods. We analyze surface gravity data from 15 SG stations and VLBI delays accumulated over the last 24 years. Results. We obtain estimates of the FCN period and quality factor that are consistent for both techniques. The inversion leads to a quality factor centered on ∼16 600 with an uncertainty of ∼3500 from SG and of ∼900 from VLBI, and to a resonant period within [−423.3, −430.5] days for SG and [−427.8, −431.4] days for VLBI (3σ interval).

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Section: Nutationmentioning

confidence: 99%

Free core nutation resonance parameters from VLBI and superconducting gravimeter data

Rosat¹,

Lambert²

2009

A&A

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“…Finally, we evaluate the combinations in terms of signal and noise in both the spectral and the spatial domains. The study is performed in the frame of the project European Gravity Service for Improved Emergency Management (EGSIEM 1 ) in preparation of a future combination service comparable to the International GNSS Service (IGS; Dow et al 2009), the International VLBI Service (IVS; Schlüter and Behrend 2007), or the International Laser Ranging Service (ILRS; Pearlman et al 2002).…”

Section: Introductionmentioning

confidence: 99%

Combination of GRACE monthly gravity field solutions from different processing strategies

Jean

Meyer

Jäggi

2018

J Geod

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We combine the publicly available GRACE monthly gravity field time series to produce gravity fields with reduced systematic errors. We first compare the monthly gravity fields in the spatial domain in terms of signal and noise. Then, we combine the individual gravity fields with comparable signal content, but diverse noise characteristics. We test five different weighting schemes: equal weights, non-iterative coefficient-wise, order-wise, or field-wise weights, and iterative field-wise weights applying variance component estimation (VCE). The combined solutions are evaluated in terms of signal and noise in the spectral and spatial domains. Compared to the individual contributions, they in general show lower noise. In case the noise characteristics of the individual solutions differ significantly, the weighted means are less noisy, compared to the arithmetic mean: The non-seasonal variability over the oceans is reduced by up to 7.7% and the root mean square (RMS) of the residuals of mass change estimates within Antarctic drainage basins is reduced by 18.1% on average. The field-wise weighting schemes in general show better performance, compared to the order-or coefficient-wise weighting schemes. The combination of the full set of considered time series results in lower noise levels, compared to the combination of a subset consisting of the official GRACE Science Data System gravity fields only: The RMS of coefficient-wise anomalies is smaller by up to 22.4% and the non-seasonal variability over the oceans by 25.4%. This study was performed in the frame of the European Gravity Service for Improved Emergency Management (EGSIEM; http://www.egsiem.eu) project. The gravity fields provided by the EGSIEM scientific combination service (ftp://ftp.aiub.unibe.ch/EGSIEM/) are combined, based on the weights derived by VCE as described in this article.

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“…It also is a component of the Australian LBA and a vital geodetic antenna regularly participating in International VLBI Service (IVS; Schlüter & Behrend 2007) observations. Hobart uses a non traditional X-Y mount slewing at 40 degrees per minute on both axes to an elevation limit of 7 degrees (apart from a 17 degree limit in the keyhole) and can observe at all major astronomical frequencies from 1.4 through 22 GHz.…”

Section: Chi: the Ceduna Hobart Interferometermentioning

confidence: 99%

High resolution rapid response observations of compact radio sources with the Ceduna Hobart Interferometer (CHI)

Blanchard

Lovell

Ojha

et al. 2012

A&A

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Context. Frequent, simultaneous observations across the electromagnetic spectrum are essential to the study of a range of astrophysical phenomena including active galactic nuclei. A key tool of such studies is the ability to observe an object when it flares i.e. exhibits a rapid and significant increase in its flux density. Aims. We describe the specific observational procedures and the calibration techniques that have been developed and tested to create a single baseline radio interferometer that can rapidly observe a flaring object. This is the only facility that is dedicated to rapid high resolution radio observations of an object south of −30 degrees declination. An immediate application is to provide rapid contemporaneous radio coverage of AGN flaring at γ-ray frequencies detected by the Fermi Gamma-ray Space Telescope. Methods. A single baseline interferometer, the Ceduna Hobart Interferometer (CHI), was formed with radio telescopes in Hobart, Tasmania and Ceduna, South Australia. A software correlator was set up at the University of Tasmania to correlate these data. Results. Measurements of the flux densities of flaring objects can be made using our observing strategy within half an hour of a triggering event. These observations can be calibrated with amplitude errors better than 15%. Lower limits to the brightness temperatures of the sources can also be calculated using CHI.

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The International VLBI Service for Geodesy and Astrometry (IVS): current capabilities and future prospects

Cited by 137 publications

References 4 publications

Free core nutation resonance parameters from VLBI and superconducting gravimeter data

Free core nutation resonance parameters from VLBI and superconducting gravimeter data

Combination of GRACE monthly gravity field solutions from different processing strategies

High resolution rapid response observations of compact radio sources with the Ceduna Hobart Interferometer (CHI)

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