A radio optical reference frame. II - Additional radio and optical source positions in the Northern Hemisphere

1991 ◽  
Vol 101 ◽  
pp. 2266 ◽  
Author(s):  
J. L. Russell ◽  
K. J. Johnston ◽  
C. Ma ◽  
D. Shaffer ◽  
C. de Vegt
Keyword(s):  
Reference Frame ◽  
Northern Hemisphere ◽  
Optical Source ◽  
Optical Reference

scholarly journals Interrelation of Present Optical and Radio Reference Frames

1984 ◽  
Vol 110 ◽  
pp. 357-360
Author(s):  
Chr. de Vegt
Keyword(s):  
Reference Frame ◽  
Northern Hemisphere ◽  
Reference Frames ◽  
Systematic Errors ◽  
Future Developments ◽  
Optical Reference

Comparison of optical and radio positions in the northern hemisphere yields local systematic differences up to 0″.2, mainly due to combined systematic errors of current optical reference frame and contributing main catalogues. Interrelations of radio/optical frame and future developments are discussed.

Radio optical reference frame. 6: Additional source positions in the northern hemisphere

1994 ◽  
Vol 107 ◽  
pp. 385 ◽  
Author(s):  
A. L. Fey ◽  
J. L. Russell ◽  
C. de Vegt ◽  
N. Zacharias ◽  
K. J. Johnston ◽  
...  
Keyword(s):  
Reference Frame ◽  
Northern Hemisphere ◽  
Additional Source ◽  
Optical Reference

A radio optical reference frame. IV - Additional radio source positions in the Northern Hemisphere

1992 ◽  
Vol 104 ◽  
pp. 891 ◽  
Author(s):  
A. L. Fey ◽  
J. L. Russell ◽  
C. Ma ◽  
K. J. Johnston ◽  
B. A. Archinal ◽  
...  
Keyword(s):  
Radio Source ◽  
Reference Frame ◽  
Northern Hemisphere ◽  
Optical Reference

scholarly journals Linking the FK5 to the ICRF

1998 ◽  
Vol 11 (1) ◽  
pp. 313-316
Author(s):  
F. Mignard ◽  
M. Froeschile
Keyword(s):  
Reference Frame ◽  
Proper Motion ◽  
Harmonic Functions ◽  
Optical Reference ◽  
Precessional Motion ◽  
Precession Constant

Abstract The Hipparcos optical reference frame is compared to the basic FK5 in order to determine the orientation at T0 = 1991.25 and the global spin between the two frames. The components of the spin are significant and suggest a correction the IAU76 value of the precession constant and to a possible non-precessional motion of the equinox of the FK5. The regional errors are analysed with harmonic functions and found to be as large as 150 mas in position and 3 mas/yr in proper motion.

scholarly journals Contributions of the USNO to the Optical Reference Frame

1997 ◽  
Vol 165 ◽  
pp. 453-462
Author(s):  
Thomas Corbin
Keyword(s):  
Reference Frame ◽  
Reverse Order ◽  
Good Working ◽  
Working Definition ◽  
Optical Reference ◽  
Definition Of ◽  
Celestial Sphere ◽  
Celestial Reference Frame ◽  
Frame Rigidity ◽  
Zero Points

A good, working definition of what is required in a celestial reference frame is that it must provide observable fiducial points on the Celestial Sphere with internally consistent positions that are referred to coordinate axes of known direction. In reality, this statement gives the goals in the reverse order from that in which each must be achieved, the definition of the axes, or zero points of the system give orientation to the observationally defined set of primary objects whose coordinate relation to each other must give the frame rigidity. Finally, the primary objects are generally too sparse to define the frame within areas of less than tens of square degrees, and so additional objects must be related to the frame to increase the density. This last step is required to make the frame useful for most observational applications.

scholarly journals Astrometric Programs by the New Hamburg Plate Measuring Machine

1994 ◽  
Vol 161 ◽  
pp. 173-176
Author(s):  
Chr. de Vegt ◽  
L. Winter ◽  
N. Zacharias
Keyword(s):  
Reference Frame ◽  
Northern Hemisphere ◽  
High Accuracy ◽  
Proper Motions ◽  
Sky Surveys ◽  
Unique Data ◽  
Large Sets ◽  
Measuring Machine ◽  
First Time

With the new Hamburg astrometric measuring machine, large sets of plates can be digitized very quickly with submicrometer accuracy. In particular about 2000 plates of the AGK2-catalog, mean epoch 1930, can be remeasured now for the first time to their limiting magnitude, about B = 11. The new AGK2-data therefore will cover practically the whole AC-catalog and TYCHO-stars in the northern hemisphere. All plates will be reduced using the HIPPARCOS results as the reference frame when available in 1996. The new AGK2-data will provide a unique data base for the determination of high accuracy proper motions (about 2 mas/yr) of all TYCHO stars in the northern hemisphere. Furthermore, for the first time a dense reference frame for a final reduction of the Astrographic Catalog (AC) and the large deep sky surveys will be generated by this catalog. The inferior situation in the southern hemisphere will be addressed briefly.

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

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.

scholarly journals RORF - A Radio Optical Reference Frame

1995 ◽  
Vol 166 ◽  
pp. 381-381
Author(s):  
N. Zacharias ◽  
A.L. Fey ◽  
J.L. Russell ◽  
K.J. Johnston
Keyword(s):  
Reference Frame ◽  
Group Delay ◽  
Phase Delay ◽  
Dual Frequency ◽  
Radio Observations ◽  
Optical Reference ◽  
Vlbi Data

The radio observations are based on more than one million pairs of group delay and phase delay rate observations from all applicable dual frequency Mark–III VLBI data from 1979 until the end of 1993.

scholarly journals Fundamental radio reference frame from VLA observations of minor planets

1988 ◽  
Vol 128 ◽  
pp. 97-97 ◽  
Author(s):  
G. H. Kaplan ◽  
K. J. Johnston ◽  
P. K. Seidelmann ◽  
C. M. Wade ◽  
T. S. Carroll
Keyword(s):  
Reference Frame ◽  
Reference Frames ◽  
Thermal Emission ◽  
Optical Observations ◽  
Minor Planets ◽  
Very Large Array ◽  
Test Particles ◽  
Optical Reference ◽  
Microwave Regime

The weak thermal emission from the largest minor planets can be detected in the microwave regime by the Very Large Array (VLA). Signal-to-noise ratios are sufficiently high to permit precise measurement of the positions of these objects at all points in their orbits with respect to background extragalactic sources. We are in the process of obtaining observations of astrometric accuracy for minor planets 1 Ceres, 2 Pallas, 4 Vesta, and 10 Hygeia.Minor planets have historically served as “test particles” in the solar system, and optical observations of these objects have been valuable in the determination of fundamental astronomical constants. In particular, optical observations of minor planets have played an important role in the establishment of the fundamental optical reference frame by permitting the determination of the orientation of the Earth's orbit relative to the stars defining the frame.Similarly, radio observations of these bodies can play a corresponding role in the establishment of a fundamental radio reference frame. Our observations will provide a direct link between the dynamical and radio reference frames, and provide important information on the relationship between the radio and optical reference frames.

scholarly journals Towards the Definition of a Unified Celestial Optical/Radio Reference Frame

1988 ◽  
Vol 129 ◽  
pp. 317-318
Author(s):  
K. J. Johnston ◽  
J. Russell ◽  
Ch. de Vegt ◽  
J. Hughes ◽  
D. Jauncey ◽  
...  
Keyword(s):  
Reference Frame ◽  
Reference Frames ◽  
Radio Observations ◽  
Minimum Density ◽  
Optical Reference ◽  
Definition Of ◽  
Celestial Reference Frame

An almost inertial celestial reference frame based upon extragalactic sources is in the process of being established. This reference frame is to be global with a minimum density of one source/100 square degrees. The source positions will be based upon radio observations and will allow optical reference frames to be related to this frame at the 0.03 arc second level.

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