Long Coherence Intercontinental Interferometry

1972 ◽  
Vol 2 (2) ◽  
pp. 114-115 ◽  
Author(s):  
J. S. Gubbay
Keyword(s):  
Fine Structure ◽  
Flux Density ◽  
Total Flux ◽  
Radio Sources ◽  
Deep Space ◽  
Deep Space Network ◽  
Space Network ◽  
Order Of Magnitude

Compact radio sources have been observed over several years at 2.3 GHz by interferometers of the NASA-JPL Deep Space Network with trans- or inter-continental baselines to study the secular behaviour of fine structure appearing in these sources. A comparison of the variation in flux density of components of diameter < 0.001 arcsec with the corresponding variation in total flux density of the source at the same frequency indicated that variations could be wholly ascribed to components of this order of magnitude.

scholarly journals Radio Reference Frame Stability from VLBI Data

1988 ◽  
Vol 129 ◽  
pp. 331-332
Author(s):  
O. J. Sovers ◽  
R. N. Treuhaft
Keyword(s):  
Reference Frame ◽  
Independent Sets ◽  
Radio Sources ◽  
Deep Space ◽  
Deep Space Network ◽  
Space Network ◽  
Rates Of Change ◽  
Upper Limits ◽  
Vlbi Data ◽  
Almost All

Intercontinental radio interferometric measurements between NASA's Deep Space Network stations yield a catalog of positions of 106 extragalactic radio sources, uniformly distributed between −45° and +85° declination. Almost all of the source positions have formal uncertainties between 0.5 and 3 milliarcseconds. Estimates of three independent sets of 32 source coordinates at average epochs 1980.0, 1983.2, and 1984.5 assess the level of stability of the reference frame over a five-year period. Comparisons of the three sets of source coordinates show a number of cases of > 2σ differences, particularly betwen the 1984–85 and 1981–83 periods. No sources, however, show 2σ shifts among both pairs of epochs. Upper limits of the order of 1 mas/yr can be placed on the time rates of change of the 32 source coordinates.

scholarly journals The JPL/DSN J2000 Radio Reference Frame

1986 ◽  
Vol 109 ◽  
pp. 163-167 ◽  
Author(s):  
A. E. Niell ◽  
J. L. Fanselow ◽  
K. M. Liewer ◽  
O. J. Sovers ◽  
J. B. Thomas ◽  
...  
Keyword(s):  
Reference Frame ◽  
High Accuracy ◽  
Radio Sources ◽  
Deep Space ◽  
Deep Space Network ◽  
Extragalactic Radio Sources ◽  
Space Network ◽  
Spacecraft Navigation ◽  
Planetary Missions ◽  
Very High

Development of a radio reference frame of very high accuracy has become necessary in order to obtain the required accuracy in spacecraft navigation for current and future planetary missions. The antennas of the NASA Deep Space Network are being utilized on a regular basis to obtain the positions of over 100 compact extragalactic radio sources distributed over the sky down to a declination of −45 degrees with uncertainties of less than 0.005 arcseconds.

scholarly journals Accurate Positions of 120 Radio Sources with Declinations Above −45°

1984 ◽  
Vol 110 ◽  
pp. 363-364
Author(s):  
A. E. Niell ◽  
J. L. Fanselow ◽  
O. J. Sovers ◽  
J. B. Thomas ◽  
K. M. Liewer ◽  
...  
Keyword(s):  
Reference Frame ◽  
Radio Sources ◽  
Deep Space ◽  
Entry Angle ◽  
Positional Accuracy ◽  
Deep Space Network ◽  
Space Network ◽  
Vlbi Observations

Development of a catalogue of approximately 100 radio sources having positional accuracy of ~0.005 arcseconds is one goal of the DSN radio reference frame program. This objective is set by the navigation requirements of the Galileo Project for reconstruction of the probe entry angle into the atmosphere of Jupiter. These radio positions are determined by VLBI observations using the antennas of the NASA Deep Space Network on two intercontinental baselines – California-Spain and California-Australia. Since 1978, measurements have been made simultaneously at 2.3 and 8.4 Ghz. Sixteen to twenty-four hours of data on each of the two baselines are usually obtained within a few days of each other, and since mid-1982 these pairs of observations have been made at approximately six week intervals.

scholarly journals Scheduling the NASA Deep Space Network with Deep Reinforcement Learning

2021 ◽  
Author(s):  
Edwin Goh ◽  
Hamsa Shwetha Venkataram ◽  
Mark Hoffmann ◽  
Mark D. Johnston ◽  
Brian Wilson
Keyword(s):  
Reinforcement Learning ◽  
Deep Space ◽  
Deep Space Network ◽  
Space Network

scholarly journals Deep Space Network Scheduling via Mixed-Integer Linear Programming

IEEE Access ◽  
2021 ◽  
Vol 9 ◽  
pp. 39985-39994
Author(s):  
Alex Sabol ◽  
Ryan Alimo ◽  
Farhad Kamangar ◽  
Ramtin Madani
Keyword(s):  
Linear Programming ◽  
Integer Linear Programming ◽  
Mixed Integer Linear Programming ◽  
Mixed Integer ◽  
Deep Space ◽  
Network Scheduling ◽  
Deep Space Network ◽  
Space Network

Two Stage Gain Magnification in Beam Wave Guide Feed of Indian Deep Space Network (IDSN-32) Station

2012 ◽  
Vol 60 (7) ◽  
pp. 3481-3484
Author(s):  
V. V. Srinivasan ◽  
C. Kumar ◽  
D. Bhatnagar ◽  
V. K. Lakshmeesha ◽  
S. Pal
Keyword(s):  
Wave Guide ◽  
Deep Space ◽  
Two Stage ◽  
Deep Space Network ◽  
Beam Wave ◽  
Space Network

scholarly journals The JPL 1986–3 Extragalactic Reference Frame

1988 ◽  
Vol 133 ◽  
pp. 461-464
Author(s):  
O.J. Sovers ◽  
C.D. Edwards ◽  
C.S. Jacobs ◽  
G.E. Lanyi ◽  
R.N. Treuhaft
Keyword(s):  
Rotation Axis ◽  
Time Variability ◽  
Radio Sources ◽  
Dual Frequency ◽  
Deep Space Network ◽  
Space Network ◽  
Celestial Sphere ◽  
Almost All ◽  
Comparable Quality

Intercontinental dual-frequency radio interferometric measurements were carried out during 1978 to 1985 between NASA's Deep Space Network stations in California, Spain, and Australia. Analysis of 6800 pairs of delay and delay rate observations made during 51 sessions produced a catalog of positions of 106 extragalactic radio sources, fairly uniformly distributed over the celestial sphere between −45° and +85° declination. Almost all of the resulting source positions have formal uncertainties between 0.5 and 3 milliarcseconds, with their distributions peaking somewhat below 1 mas. Root-mean-square uncertainties are 2.1 and 2.0 mas for RA and declination, respectively. Evidence is found for a long-term drift of the Earth's rotation axis in inertial space, relative to the 1984 IAU precession and nutation models. Tests for time variability of positions of 32 frequently observed sources place limits at the 1 mas/yr level. Comparisons with independently determined source catalogs of comparable quality show differences of positions of common sources that amount to a few mas, and may indicate the level of systematic errors in VLBI source position measurements.

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