The Celestial Reference Frame Defined by VLBI

VLBI currently produces the most accurate positions of celestial objects. From 1979 to 1987, 114 extragalactic radio sources have been observed with dual-frequency Mark III VLBI as part of the NASA Crustal Dynamics Project and the NGS POLARIS/IRIS program. The formal statistical errors of conventional celestial coordinates are as small as 0.3 milliarcseconds. The fundamental quantity measured by VLBI is the arc length between radio sources. Thus, we suggest that VLBI be used to establish a coordinate reference frame based solely on radio positions, and that this system not necessarily be coupled to right ascension and declination.

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The VLBI celestial reference frame of the NASA Crustal Dynamics Project

Symposium - International Astronomical Union ◽

10.1017/s0074180900119308 ◽

1988 ◽

Vol 128 ◽

pp. 73-81 ◽

Cited By ~ 2

Author(s):

C. Ma

Keyword(s):

Reference Frame ◽

Weighted Average ◽

Radio Sources ◽

Extragalactic Radio Sources ◽

Statistical Errors ◽

Crustal Dynamics ◽

Vlbi Data ◽

Celestial Reference Frame ◽

Right Ascension ◽

Average Position

A celestial reference frame can be defined by precise positions of extragalactic radio sources using Mark III VLBI data available to the NASA Crustal Dynamics Project for geodynamic research. Seven years of such data have been analyzed to generate a catalogue of 101 sources with formal statistical errors between 0.01 and 0.77 ms in right ascension and between 0.2 and 9.3 mas in declination. In order to achieve such precision it is necessary to adjust the standard IAU nutation model. The rotations and scatter of the positions from year to year are generally less than 1 mas. A comparison of this catalogue with a completely independent catalogue derived from Mark II data shows a weighted average position difference, after a rotation, of 1.9 mas.

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Stability of the Extragalactic Reference Frame Realized by VLBI

International Astronomical Union Colloquium ◽

10.1017/s0252921100063685 ◽

1991 ◽

Vol 127 ◽

pp. 135-144 ◽

Cited By ~ 1

Author(s):

C. Ma ◽

D.B. Shaffer

Keyword(s):

Reference Frame ◽

Radio Sources ◽

Dual Frequency ◽

Real Motion ◽

Rates Of Change ◽

Upper Limits ◽

Crustal Dynamics ◽

Vlbi Data ◽

Celestial Reference Frame ◽

Right Ascension

AbstractThe 318 compact extragalactic radio sources with positions derived from dual frequency Mark III VLBI data acquired by the geodetic and astrometric programs of NASA, NOAA, NRL and USNO form a celestial reference frame with stability in orientation and relative position at the 1 mas level. This paper examines the reference frame realized using 461,000 observations from 1021 observing sessions between 1979 August and 1990 August in the NASA Crustal Dynamics Project VLBI data base. Catalogs of positions estimated from subsets of data (annual, seasonal, network) show differences in orientation typically less than 1 mas provided precession and nutation are adjusted using a reference day. For 17 sources with >5 year time span and >200 one-day position estimates, the rates of change of right ascension and declination are generally less than 5 mas/century, giving upper limits on real motion.

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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.

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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).

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Realization of an Inertial Reference Frame From Mark III VLBI

Symposium - International Astronomical Union ◽

10.1017/s0074180900086927 ◽

1990 ◽

Vol 141 ◽

pp. 271-280 ◽

Cited By ~ 2

Author(s):

C. Ma

Keyword(s):

Reference Frame ◽

Standard Errors ◽

Radio Sources ◽

Inertial Reference Frame ◽

Dual Frequency ◽

Extragalactic Radio Sources ◽

Vlbi Observations

Over 350 000 dual frequency Mark III VLBI observations from several geodetic and astrometric observing programs have been used to realize an inertial reference frame through the positions of 325 compact extragalactic radio sources uniformly distributed over the sky with standard errors typically under 1 milliarcsecond (mas). Internal and external tests indicate that the reference frame defined by the relative positions of these radio sources should be accurate and stable at the 1-2 mas level. Because the conventional precession and nutation models are adjusted in the estimation of the source positions, the positions and relative angles are not degraded over the interval of observations or at epochs away from the reference epoch.

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Structure Effects for 3417 Celestial Reference Frame Radio Sources

The Astrophysical Journal Supplement Series ◽

10.3847/1538-4365/ab16ea ◽

2019 ◽

Vol 242 (1) ◽

pp. 5 ◽

Cited By ~ 6

Author(s):

M. H. Xu ◽

J. M. Anderson ◽

R. Heinkelmann ◽

S. Lunz ◽

H. Schuh ◽

...

Keyword(s):

Reference Frame ◽

Radio Sources ◽

Celestial Reference Frame

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The Possibility to Link Radio and Optical Reference Frames With Artificial Satellites

Symposium - International Astronomical Union ◽

10.1017/s0074180900086794 ◽

1990 ◽

Vol 141 ◽

pp. 194-194

Author(s):

Tong Fu

Keyword(s):

Reference Frame ◽

Reference Frames ◽

Artificial Satellites ◽

Radio Sources ◽

Bl Lac Objects ◽

Extragalactic Radio Sources ◽

Bl Lac ◽

Optical Reference ◽

Radio Stars ◽

Fundamental Reference

Based on extragalactic radio sources, a new high precision extragalactic radio reference frame can be established from radio interferometric measurements. To link the optical fundamental reference frame presently represented by the FK4/5 to the extragalactic radio frame, the optical counterparts of extragalactic radio sources (quasars, BL Lac objects etc.) and radio stars are the most important classes of objects. Besides these two classes of objects, are there any other objects which can be used to link the optical and radio frames? A posible answer is that artificial satellites could be a candidate class of objects contributing to this subject.

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An Extragalactic Reference Frame From DSN VLBI Measurements–1989

Symposium - International Astronomical Union ◽

10.1017/s0074180900086915 ◽

1990 ◽

Vol 141 ◽

pp. 261-270 ◽

Cited By ~ 4

Author(s):

O. J. Sovers

Keyword(s):

Reference Frame ◽

Systematic Errors ◽

Radio Sources ◽

Dual Frequency ◽

Source Position ◽

Deep Space Network ◽

Space Network ◽

Data Analyses ◽

Accuracy Level ◽

The Impact

Assessment of the impact of recent improvements in Deep Space Network (DSN) instrumentation, as well as of joint data analyses, provide a prognosis for the accuracy level to be expected in future realizations of an inertial radio reference frame. Intercontinental dual-frequency radio interferometric measurements during 68 sessions (including two recent sessions employing Mark III instrumentation) from 1978 to 1989 using NASA's DSN stations in California, Spain, and Australia give 8900 pairs of delay and delay rate observations. Analysis yields a catalog of positions of 200 extragalactic radio sources north of —45° declination. The resulting source position formal uncertainty distributions peak below 1 milliarcsecond, with three fourths being smaller than 2 mas. Comparison with independent measurements shows some evidence for systematic errors at the milliarcsecond level.

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OPTICAL SPECTRA OF CANDIDATE SOUTHERN HEMISPHERE INTERNATIONAL CELESTIAL REFERENCE FRAME (ICRF) RADIO SOURCES

The Astronomical Journal ◽

10.1088/0004-6256/142/5/165 ◽

2011 ◽

Vol 142 (5) ◽

pp. 165 ◽

Cited By ~ 14

Author(s):

O. Titov ◽

D. L. Jauncey ◽

H. M. Johnston ◽

R. W. Hunstead ◽

L. Christensen

Keyword(s):

Reference Frame ◽

Southern Hemisphere ◽

Optical Spectra ◽

Radio Sources ◽

Celestial Reference Frame

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Instability of the celestial reference frame and effect on UT1

Proceedings of the International Astronomical Union ◽

10.1017/s1743921310008793 ◽

2009 ◽

Vol 5 (H15) ◽

pp. 209-209

Author(s):

Vladimir E. Zharov

Keyword(s):

Reference Frame ◽

Apparent Motion ◽

Radio Sources ◽

Secular Variations ◽

Celestial Reference Frame

AbstractIt was shown that the ICRF radio sources including the defining sources have significant apparent motion that leads to rotation of the ICRF. This rotation is transformed to secular variations of EOP that is decreased or removed if motion of sources is took into account.

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