Radio-source positions from VLBI

Ma, C.; Clark, T. A.; Ryan, J.; Herring, T. A.; Shapiro, I. I.; Corey, B. E.; Hinteregger, H. F.; Rogers, A. E. E.; Whitney, A. R.; Knight, C. A.; Lundqvist, G.; Shaffer, D. B.; Vandenberg, N. R.; Pigg, J.C.; Schupler, B. R.; Ronnang, B. O.

doi:10.1086/114232

Cited by 62 publications

(21 citation statements)

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“…Catalogs using Mark III technology achieved an accuracy of less than 0.5 mas for the best positions (Ma et al 1986, Robertson et al 1986; Mark II measurement by Sovers et al (1988) achieved the same level of accuracy.…”

Section: The Radio Reference Framementioning

confidence: 94%

“…The MERIT standards were brought forth to update the 1976 IAU standards (Melborne et al 1983). Two different software analysis systems evolved for the reduction of VLBI data: MASTERFIT (Sovers & Fanselow 1987), developed by the Jet Propulsion Laboratory, and CALC /SOLVE/GLOBL, developed jointly by the Goddard Space Flight Center, the Harvard-Smithsonian Center for Astrophysics, and the National Geodetic Survey (Robertson 1975, Ma 1978, Gordon 1985, Ma et al 1986. Both sets of software were found to deviate in theoretical delays by 1.5 to 50 picoseconds, not including the comparison of the different tropospheric and relativistic models used by each (Sovers and Ma 1985).…”

Section: The Radio Reference Framementioning

confidence: 99%

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Reference Frames in Astronomy

Johnston¹,

Vegt²

1999

Annu. Rev. Astron. Astrophys.

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Key Words astrometry, reference frames, reference systems s Abstract Advances in wide-angle astrometric measurements of three to four orders of magnitude in the last thirty years have resulted in a redefinition of the fundamental astronomical reference frame. This new frame, the International Celestial Reference Frame (ICRF), is based on the radio positions of 212 compact extragalactic radio sources. The ICRF defines the direction of the axes of the International Celestial Reference System (ICRS) with a precision of approximately 20 µas. At optical wavelengths, the Hipparcos catalog is the realization of this frame. The precision with which the ICRF is now determined requires that the ICRS models for precession, nutation, and others, be revised. Increases in the precision of measurements from astrometric space missions will further improve the celestial reference frame and may require its redefinition within the next ten years. These improvements will again challenge the models for the celestial reference system.

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Section: The Radio Reference Framementioning

confidence: 94%

Section: The Radio Reference Framementioning

confidence: 99%

Reference Frames in Astronomy

Johnston¹,

Vegt²

1999

Annu. Rev. Astron. Astrophys.

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“…The catalogues used and their intemal abbreviations are: Q17 (Fanselow et al, 1984), Q19B (Ma et al, 1986), Q22A , Q23 (Ma, 1988), Q27 (Sovers et al, 1989), and Q28 (Ma et al, 1990). These catalogues have in common that the positions of the extragalactic objects are given by right ascension (RA) and declination (Dec) referring to the coordinate system J2000.0, and in most of the cases the origin of RA is adopted from the predefined RA of the source 3C273B = 1226 + 023.…”

Section: Observational Datamentioning

confidence: 99%

Corrections to the luni-solar precession derived from a compilation catalogue of extragalactic radio sources

Walter¹

1992

Celestial Mech Dyn Astr

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Observation catalogues of extragalactic radio sources obtained by Very long Baseline Interferometry during the last decade agree in the mean to a few milliarcseconds (mas). Within this range the position differences show constant, linear and periodic offsets. To reduce the influence of individual catalogue properties the construction of a compilation catalogue seems to be the appropriate procedure. In some detail the compilation method is described providing simultaneous adjustment of source positions and catalogue corrections. The compilation catalogue consists of 40 objects having positional errors of 0.2 mas in right ascension (RA) and 0.3 mas in declination (Dec). Comparing this catalogue with the IERS Celestial Reference Frame compiled by means of other precepts yields weighted root-mean-square differences of 0.7 mas in RA and 1.3 mas in Dec. Finally, the terms of general precession in RA and Dec are included in the adjustment process giving estimates of the correction to the luni-solar precession between -1 and -3 mas/yr, the latter figure applying when some early data are added.

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“…The reduction software system is CALC/SOLVE/GLOBL (Ma et al, 1986). The basic models used to calculate the VLBI delays are generally consistent with the 1996 IERS Conventions (McCarthy, 1996).…”

Section: Introductionmentioning

confidence: 99%

Global solution of VLBI observations and assessments

Wang

2014

Earth Planet Sp

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Mark III VLBI observations between August 1979 and December 1998 were analyzed to yield the terrestrial and celestial reference frames (TRF and CRF) and the Earth Orientation Parameters (EOP). Comparisons with ITRF96, RSC (WGRF) 95 R01 and EOP (IERS) 97 C04 are performed. For CRF, the three orientation angles are not significant at the level of precision of 0.1 mas. Though no significant values are found for the three deformation parameters, coordinate drifts up to 0.5 mas are identifiable for some sources in the southern hemisphere. The relative rotation angles and their rates of change for TRF are not significant respectively at the precision level of 0.2 mas and 0.1 mas/yr. Detailed comparisons however show that the differences in the velocity field are obvious for the eastern part of Eurasian plate and Australian plate. About EOP series, the systematic differences and the relative drifts are not significant respectively at the level of 0.4 mas and 0.1 mas/yr.

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Radio-source positions from VLBI

Cited by 62 publications

References 0 publications

Reference Frames in Astronomy

Reference Frames in Astronomy

Corrections to the luni-solar precession derived from a compilation catalogue of extragalactic radio sources

Global solution of VLBI observations and assessments

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