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Science 14 July 1967:
Vol. 157. no. 3785, pp. 189 - 191
DOI: 10.1126/science.157.3785.189
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Articles

Interferometer Experiment with Independent Local Oscillators

C. Bare 1, B. G. Clark 1, K. I. Kellermann 1, M. H. Cohen 2, and D. L. Jauncey 3

1 National Radio Astronomy Observatory, Green Bank, West Virginia
2 University of California, San Diego, La Jolla
3 Center for Radiophysics and Space Research, Cornell University, Ithaca, New York

We have operated an interferometer with independent local oscillators and without any communication link of wide bandwidth between the elements of the interferometer. This makes operation possible at very long base lines because, heretofore, construction of the communications link has been the factor limiting the separation of the elements. In our system, coherence at the two elements is maintained through the use of two highly stable, atomic oscillators. The intermediate-frequency output signals are recorded at each element on a high-speed digital tape recorder. Interference fringes are produced later by cross-correlating the two tape records in a digital computer.


THIS ARTICLE HAS BEEN CITED BY OTHER ARTICLES:
Very Long Baseline Interferometric Observations Made with an Orbiting Radio Telescope.
G. S. LEVY, R. P. LINFIELD, J. S. ULVESTAD, C. D. EDWARDS, J. F. JORDAN JR., S. J. DI NARDO, C. S. CHRISTENSEN, R. A. PRESTON, L. J. SKJERVE, L. R. STAVERT, et al. (1986)
Science 234, 187-189
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The Very Long Baseline Array.
K. I. Kellermann and A. R. Thompson (1985)
Science 229, 123-130
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Very-Long-Baseline Radio Interferometry: The Mark III System for Geodesy, Astrometry, and Aperture Synthesis.
A. E. E. Rogers, A. E. E. ROGERS, R. J. CAPPALLO, H. F. HINTEREGGER, J. I. LEVINE, E. F. NESMAN, J. C. WEBBER, A. R. WHITNEY, T. A. CLARK, C. MA, et al. (1983)
Science 219, 51-54
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Real-Time, Very-Long-Baseline Interferometry Based on the Use of a Communications Satellite.
J. L. YEN, K. I. KELLERMANN, B. RAYHRER, N. W. BROTEN, D. N. FORT, S. H. KNOWLES, W. B. WALTMAN, and G. W. SWENSON JR. (1977)
Science 198, 289-291
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Transcontinental Baselines and the Rotation of the Earth Measured by Radio Interferometry.
I. I. Shapiro, I. I. Shapiro, D. S. Robertson, C. A. Knight, C. C. Counselman III, A. E. E. Rogers, H. F. Hinteregger, S. Lippincott, A. R. Whitney, T. A. Clark, et al. (1974)
Science 186, 920-922
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Precision Geodesy via Radio Interferometry.
H. F. Hinteregger, H. F. Hinteregger, I. I. Shapiro, D. S. Robertson, C. A. Knight, R. A. Ergas, A. R. Whitney, A. E. E. Rogers, J. M. Moran, T. A. Clark, et al. (1972)
Science 178, 396-398
   Abstract »    PDF »
Radio Interferometry at One-Thousandth Second of Arc.
M. H. Cohen, D. L. Jauncey, K. I. Kellermann, and B. G. Clark (1968)
Science 162, 88-94
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Radio Method for the Precise Measurement of the Rotation Period of the Earth.
T. Gold and T. Gold (1967)
Science 157, 302-304
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