Linking the Dynamical Reference frame to
                                                  the ICRF

Abstract The latest JPL planetary and lunar ephemerides, DE405, are referenced to the International Celestial Reference Frame (ICRF) with an accuracy that approaches 1 mas for the four innermost planets, the sun, and the moon. This has been accomplished mainly by 18 VLBI observations of the Magellan Spacecraft in orbit around Venus. The ephemeris of Jupiter, however, is not well-determined since the various observations are not consistent within each other. The outer four planets continue to rely almost entirely upon optical observations; their ephemeris uncertainties lie in the 100-200 mas range.

Download Full-text

Astrometry and Geodesy from VLBI

Symposium - International Astronomical Union ◽

10.1017/s0074180900173140 ◽

1993 ◽

Vol 156 ◽

pp. 159-171

Author(s):

C. Ma ◽

J. L. Russell

Keyword(s):

Reference Frame ◽

Reference Frames ◽

Radio Sources ◽

Dual Frequency ◽

Terrestrial Reference Frames ◽

Vlbi Observations ◽

Using Data ◽

Celestial Reference Frame ◽

Right Ascension ◽

Better Than

Dual frequency Mark III VLBI observations acquired since 1979 by several geodetic and astrometric observing programs have been used to establish precise celestial and terrestrial reference frames. The program to establish a uniformly distributed celestial reference frame of ∼400 compact radio sources with optical counterparts was begun in 1987. Some 700 sources have been considered as part of this effort and a preliminary list of ∼400 has been observed. At present, 308 sources have formal 1σ errors less than 1 mas in right ascension and 308 have similar precision in declination. The astrometric results include some data acquired for geodetic purposes. The geodetic results using data to September, 1992 include the positions of 105 sites with formal 1σ horizontal errors generally less than 1 cm at 1992.6 and the velocities of 64 sites with formal 1σ horizontal errors generally better than 2 mm/yr.

Download Full-text

On the Geodetic Rotation of the Major Planets, the Moon and the Sun

Artificial Satellites ◽

10.2478/v10018-009-0018-3 ◽

2009 ◽

Vol 44 (2) ◽

pp. 43-52

Author(s):

G. Eroshkin ◽

V. Pashkevich

Keyword(s):

Angular Velocity ◽

Reference Frame ◽

Velocity Vector ◽

Previous Investigation ◽

The Body ◽

The Other ◽

The Sun ◽

The Moon ◽

Angular Velocity Vector

On the Geodetic Rotation of the Major Planets, the Moon and the SunThe problem of the geodetic (relativistic) rotation of the major planets, the Moon and the Sun was studied in the paper by Eroshkin and Pashkevich (2007) only for the components of the angular velocity vectors of the geodetic rotation, which are orthogonal to the plane of the fixed ecliptic J2000. This research represents an extension of the previous investigation to all the other components of the angular velocity vector of the geodetic rotation, with respect to the body-centric reference frame from Seidelmann et al. (2005).

Download Full-text

Models for Source Structure Corrections

International Astronomical Union Colloquium ◽

10.1017/s0252921100000075 ◽

2000 ◽

Vol 180 ◽

pp. 29-39

Author(s):

P. Charlot

Keyword(s):

Reference Frame ◽

Very Long Baseline Interferometry ◽

Radio Sources ◽

Time Varying ◽

Long Baseline ◽

Vlbi Observations ◽

Spatially Extended ◽

Astrometric Data ◽

Celestial Reference Frame ◽

Source Structure

AbstractAt the milliarcsecond scale, most of the extragalactic radio sources exhibit spatially-extended intrinsic structures which are variable in both time and frequency. Such radio structures set limits on the accuracy of source positions determined with the Very Long Baseline Interferometry (VLBI) technique unless their effects in the astrometric data can be accounted for. We review the modeling scheme for calculating source structure corrections and discuss the magnitude and impact of these effects for the sources that are part of the International Celestial Reference Frame (ICRF). Results obtained by applying source structure corrections to actual VLBI observations on the time-varying source 4C39.25 (0923 + 392) are also presented.

Download Full-text

Formation of The International Celestial Reference Frame

Highlights of Astronomy ◽

10.1017/s153929960002075x ◽

1998 ◽

Vol 11 (1) ◽

pp. 281-286

Author(s):

C. Ma ◽

E.F. Arias ◽

T.M. Eubanks ◽

A.L. Fey ◽

A.-M. Gontier ◽

...

Keyword(s):

Reference Frame ◽

Reference Frames ◽

Terrestrial Reference Frame ◽

Naval Research ◽

Dual Frequency ◽

Cooperative Effort ◽

Space Navigation ◽

Vlbi Observations ◽

Crustal Dynamics ◽

Celestial Reference Frame

The goal of the work described here is to create the definitive catalogue for the new International Celestial Reference Frame (ICRF) using the best data and methods available at the time the work was done. This work is the joint cooperative effort of a subgroup of the IAU Working Group on Reference Frames which was formed expressly for this purpose in February 1995. The authors of this report constituted the subgroup. A fuller account of this report can be found in the introduction to the ICRF catalog (IERS 1997). The ICRF of 608 sources presented here is based on essentially all the VLBI observations accu-mulated over about 15 years in several worldwide programs. Dual frequency Mark III data have both geodetic and astrometric applications. Most of the data (95% of nearly 2 million observations) were acquired primarily for geodetic purposes. The major geodetic programs include: NASA’s Crustal Dynamics Project/Space Geodesy Program and USNO’s NAVEX sessions for the terrestrial reference frame, as well as IRIS, NAVNET and NEOS sessions for monitoring Earth rotation. The geodetic programs have used the brightest radio sources, gradually concentrating on the most com-pact as sensitivity improved. These geodetic sources were also the foundation of astrometric work because of the large number of observations for the ~150 most commonly used. The astrometric programs which densify the sky include the Radio-Optical Reference Frame sessions done by US Naval Research Laboratory (NRL) and USNO and the space navigation efforts of Jet Propulsion Laboratory (JPL).

Download Full-text

CQSSP: A New Technique for Establishing the Tie Between the Stellar and Quasar Celestial Reference Frames

International Astronomical Union Colloquium ◽

10.1017/s0252921100064174 ◽

1991 ◽

Vol 127 ◽

pp. 341-347

Author(s):

T. Schildknecht ◽

I. Bauersima ◽

U. Hugentobler ◽

A. Verdun ◽

G. Beutler

Keyword(s):

Reference Frame ◽

Earth Rotation ◽

Reference Frames ◽

Terrestrial Reference Frame ◽

Optical Observations ◽

Artificial Satellites ◽

Satellite Orbits ◽

Earth Rotation Parameters ◽

A New Technique ◽

Celestial Reference Frame

AbstractUsing artificial satellites as transfer objects the project “Coupled Quasar-Satellite-Star Positioning” represents an independent method for linking quasar and stellar reference frames. Optical observations of close approaches between reference stars and satellites yield satellite positions in the stellar reference frame. On the other hand high precision satellite orbits in the International Earth Rotation Service (IERS) terrestrial reference frame are obtained from laser or radiometric observations. Using IERS earth rotation parameters and adopted transformation models the satellite and eventually the star positions can be expressed in the IERS quasar celestial reference frame. In this paper we describe the CQSSP project and assess its capability for providing an accurate tie between tho two metioned celestial reference frames.

Download Full-text

Carlsberg Positions of Planets Compared with JPL DE403

International Astronomical Union Colloquium ◽

10.1017/s0252921100047084 ◽

1997 ◽

Vol 165 ◽

pp. 541-546

Author(s):

L.V. Morrison ◽

M.E. Buontempo

Keyword(s):

Solar System ◽

Reference Frame ◽

Systematic Difference ◽

Outer Solar System ◽

Vlbi Observations ◽

Solar System Objects ◽

Hipparcos Catalogue ◽

Preliminary Version ◽

Celestial Reference Frame

AbstractThe Carlsberg meridian telescope has made nearly 20 000 observations of outer Solar System objects since it began operation in 1984. A preliminary version of the Hipparcos catalogue has been used to refer the positions to the International Celestial Reference Frame (ICRF). The observed positions of the major planets are compared with JPL DE403 which is also referred to the ICRF. The agreement with DE403 is good, except for the declination of Jupiter where there is a systematic difference reaching 015 in 1995. The cause of this discrepancy is being investigated at JPL with recent VLBI observations of Galileo.

Download Full-text

Residual rotation of the FK5 from optical observations of the planets 1960–1994

Symposium - International Astronomical Union ◽

10.1017/s0074180900127913 ◽

1996 ◽

Vol 172 ◽

pp. 477-480

Author(s):

Yu. B. Kolesnik

Keyword(s):

Reference Frame ◽

World Wide ◽

Stellar System ◽

Optical Observations ◽

The Sun

In the interval covering last three decades optical observations of the Sun and major planets have been produced with an unprecedented intensity. Most of the published world-wide observations of the Sun, Mercury, Venus and Mars made from 1960 to 1994 with transit circles, astrographs and astrolabes are incorporated here for investigation of the residual rotation of the stellar system with respect to the dynamical reference frame.

Download Full-text

Analysis of the Secular Variations of Longitudes of the Sun, Mercury and Venus from Optical Observations

Highlights of Astronomy ◽

10.1017/s1539299600013678 ◽

2002 ◽

Vol 12 ◽

pp. 330-333

Author(s):

Y.B. Kolesnik

Keyword(s):

Secular Variation ◽

Optical Observations ◽

Lunar Theory ◽

The Sun ◽

The Moon ◽

Significant Discrepancy ◽

Secular Variations ◽

Tidal Acceleration

AbstractAbout 240 000 optical observations of the Sun, Mercury and Venus, accumulated during the era of classical astrometry from Bradley up to our days, are incorporated to analyse the secular variation of the longitudes of innermost planets. A significant discrepancy between modern ephemerides and optical observations is discovered. The possible sources of discrepancy are discussed. The tidal acceleration of the Moon has been revised to conform the lunar theory with the ephemerides of the planets. The offset and residual rotation of Hipparcos-based system with respect to the dynamical equinox is determined. Interpretation of this rotation is given.

Download Full-text

Video Grazing Occultations

International Astronomical Union Colloquium ◽

10.1017/s0252921100092447 ◽

1988 ◽

Vol 98 ◽

pp. 120-121

Author(s):

David W. Dunham

Keyword(s):

Reference Frame ◽

Solar Eclipse ◽

Close Binaries ◽

Galactic Rotation ◽

The Sun ◽

The Moon ◽

The Earth

Grazing occultations are always visible at the projections onto the surface of the Earth of the lines tangent to the lunar limb that are created by the motion of the Moon relative to the star being occulted.Most information about the lunar profile continues to be provided by visual observers using simple equipment. Everyone is to be encouraged to join expeditions to observe grazes, because the accuracy of the observed profile is proportional to the number of stations. The use of grazes improves knowledge of the lunar profile (needed for the analysis of solar eclipse timings), data about close binaries, and galactic rotation from stellar reference-frame determination. Contact timings made near the edges of a solar eclipse track, for example, enable the diameter of the Sun to be derived relative to the lunar diameter, the latter being determined from occultations.

Download Full-text

VLBI observations of weak extragalactic radio sources for the alignment of the future Gaia frame with the ICRF

Proceedings of the International Astronomical Union ◽

10.1017/s1743921308019467 ◽

2007 ◽

Vol 3 (S248) ◽

pp. 324-325

Author(s):

G. Bourda ◽

P. Charlot ◽

R. Porcas ◽

S. Garrington

Keyword(s):

Radio Emission ◽

Reference Frame ◽

Radio Sources ◽

High Quality ◽

Preliminary Results ◽

Vlbi Observations ◽

Extended Radio ◽

Optical Wavelengths ◽

Space Astrometry ◽

Celestial Reference Frame

AbstractThe space astrometry mission Gaia will construct a dense optical QSO-based celestial reference frame. For consistency between the optical and radio positions, it will be important to align the Gaia frame and the International Celestial Reference Frame (ICRF) with the highest accuracy. Currently, it is found that only 10% of the ICRF sources are suitable to establish 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. In order to improve the situation, we have initiated a VLBI survey dedicated to finding additional high-quality radio sources for aligning the two frames. The sample consists of about 450 sources, typically 20 times weaker than the current ICRF sources, which have been selected by cross-correlating optical and radio catalogues. This paper presents the observing strategy and includes preliminary results of observation of 224 of these sources with the European VLBI Network in June 2007.

Download Full-text