The International Celestial Reference Frame as Realized by Very Long Baseline Interferometry

Ma, C.; Arias, E. F.; Eubanks, T. M.; Fey, A. L.; Gontier, A. M.; Jacobs, Christopher S.; Sovers, O. J.; Archinal, B. A.; Charlot, P.

doi:10.1086/300408

Cited by 709 publications

(569 citation statements)

References 26 publications

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“…complete Table 3) is only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/520/A113 radio sources (Ma et al 1998), with supplementary positions for 109 sources added in a second stage (Fey et al 2004). The coordinates of these radio sources were estimated through Very Long Baseline Interferometry (VLBI) measurements, from dual-frequency S /X observations (2.3 and 8.4 GHz), with a noise floor of 250 microarcseconds (μas).…”

Section: Introductionmentioning

confidence: 99%

VLBI observations of optically-bright extragalactic radio sources for the alignment of the radio frame with the future Gaia frame

Bourda

Charlot

Porcas

et al. 2010

A&A

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Context. The European space astrometry mission Gaia will construct a dense optical QSO-based celestial reference frame. For consistency between optical and radio positions, it will be important to align the Gaia and VLBI frames with the highest possible accuracy. It has been found that only 70 (10%) of the sources from the International Celestial Reference Frame (ICRF) are suitable for establishing this link, either because they are not bright enough at optical wavelengths or because they have significant extended radio emission which precludes reaching the highest astrometric accuracy. Aims. In order to improve the situation, we have initiated a VLBI survey dedicated to finding additional suitable radio sources for aligning the two frames. Methods. The sample consists of 447 optically-bright (magnitude ≤18) extragalactic radio sources, typically 20 times weaker than the ICRF sources, which have been selected by cross-correlating an optical quasar catalog with the NRAO VLA Sky Survey (NVSS).Results. This paper presents the observing strategy to detect, image, and measure accurate radio positions for these sources. It also provides results on the VLBI detectability of the sources, as derived from initial observations with the European VLBI Network in June and October 2007. Based on these observations, a high detection rate of 89% is found, which is promising for the continuation of this project. This high VLBI detection rate for sources from the NVSS catalog is probably due to the selection process, suggesting that optically-bright quasars have compact radio structures.

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Section: Introductionmentioning

confidence: 99%

VLBI observations of optically-bright extragalactic radio sources for the alignment of the radio frame with the future Gaia frame

Bourda

Charlot

Porcas

et al. 2010

A&A

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“…It has 212 defining (setting the ICRF axes) sources with individual positions better than 1mas that were chosen based on their observing history, the stability, and accuracy of their position estimates. In the original realization ICRF also included positions for 396 sources to make the frame denser (Ma et al 1998). Later ICRF was extended to include an additional 109 sources (Fey et al 2004).…”

Section: Quasarsmentioning

confidence: 99%

Apparent close approaches between near-Earth asteroids and quasars

Nedelcu

Birlan

Souchay³

et al. 2009

A&A

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Aims. We investigate the link between the International Celestial Reference Frame (ICRF) and the dynamical reference frame realized by the ephemerides of the Solar System bodies. Methods. We propose a procedure that implies a selection of events for asteroids with accurately determined orbits crossing the CCD field containing selected quasars. Using a Bulirsch-Stoer numerical integrator, we constructed 8-years (2010-2018) ephemerides for a set of 836 numbered near-Earth asteroids (NEAs). We searched for close encounters (within a typical field of view of groundbased telescopes) between our selected set of asteroids and quasars with high-accuracy astrometric positions extracted from the Large Quasars Astrometric Catalog (LQAC). Results. In the designated period (2010-2018), we found a number of 2924, 14 257, and 6972 close approaches (within 10 ) between asteroids with a minimum solar elongation value of 60 • and quasars from the ICRF-Ext2, the Very Large Baseline Array Calibrator Survey (VLBA-CS), and the Very Large Array (VLA), respectively. This large number of close encounters provides the observational basis needed to investigate the link between the dynamical reference frame and the ICRF.

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“…The fundamental properties of the ICRS, which has been adopted as the International Celestial Reference System (Ma et al 1998), are the absence of global rotation and the abandonment of the link with the motion of the Earth. It is thus necessary to abandon the current parameters in the FK5 System which combine the motions of the equator and the ecliptic and to replace them by a minimal number of parameters, based on the location and motion of the rotation pole only without any relation to the orbital motion of the Earth.…”

Section: Definition and Use Of The Celestial And Terrestrial Ephemerimentioning

confidence: 99%

New Definition for the Celestial Pole and the Celestial Origin in the ICRS

Capitaine

2002

Highlights astron.

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Abstract. Two Resolutions have been submitted to the 24 th General Assembly of the IAU concerning the definition and use of the celestial pole of reference and the celestial origin. The aim of both resolutions is to provide new parameters for Earth rotation which are consistent with the properties of the International Celestial Reference System (ICRS), adopted from 1 January 1998 as the IAU celestial reference system. The definition of the parameters have also to be consistent with the precision and the temporal resolution of the current Earth rotation measurements as well as with the theory for nutation and polar motion at the microarcsecond level. This paper explains the basis of the resolutions as well as their practical application. One of the resolutions defines the "Celestial Intermediate Pole" (CIP) in order to replace the "Celestial Ephemeris Pole" (CEP) for the new IAU precession-nutation model; its specifies the way for taking into account the constant offset from the ICRS and the high frequency terms in polar motion and nutation. The other resolution recommends the use of the "non-rotating origin" (Guinot 1979) on the moving equator, for defining Earth rotation and UT1; it also recommends the use of the celestial and terrestrial coordinates of the CIP in the transformation from the celestial to the terrestrial systems.

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The International Celestial Reference Frame as Realized by Very Long Baseline Interferometry

Cited by 709 publications

References 26 publications

VLBI observations of optically-bright extragalactic radio sources for the alignment of the radio frame with the future Gaia frame

VLBI observations of optically-bright extragalactic radio sources for the alignment of the radio frame with the future Gaia frame

Apparent close approaches between near-Earth asteroids and quasars

New Definition for the Celestial Pole and the Celestial Origin in the ICRS

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