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The milli-arcsecond images of Q0957 + 561
Gorenstein, M. V.; Shapiro, I. I.; Rogers, A. E. E.; Cohen, N. L.; Corey, B. E.; Porcas, R. W.; Falco, E. E.; Bonometti, R. J.; Preston, R. A.; Rius, A.; Whitney, A. R.
AA(Harvard-Smithsonian Center for Astrophysics; MIT, Cambridge, MA), AB(Harvard-Smithsonian Center for Astrophysics; MIT, Cambridge, MA), AC(Haystack Observatory, Westford, MA), AD(Harvard-Smithsonian Center for Astrophysics, Cambridge, MA; Cornell University, Ithaca, NY), AE(MIT, Cambridge; Haystack Observatory, Westford, MA), AF(Max-Planck-Institut für Radioastronomie, Bonn, Germany), AG(MIT, Cambridge, MA), AH(MIT, Cambridge, MA), AI(California Institute of Technology, Jet Propulsion Laboratory, Pasadena, CA), AJ(NASA Instituto Nacional de Tecnica Aeroespacial, Madrid, Spain)
Astrophysical Journal, Part 1 (ISSN 0004-637X), vol. 287, Dec. 15, 1984, p. 538-548. (ApJ Homepage)
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NASA/STI Keywords:
Brightness Distribution, Gravitational Fields, Quasars, Radio Sources (Astronomy), Very Long Base Interferometry, Centimeter Waves, Flux Density, Gravitational Lenses
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The authors detected similar compact radio structures in the A and B images of the quasar Q0957+561 from observations in 1980 February that utilized a three-element VLBI array operating at 13 cm (2292 MHz). The array included antennas at Goldstone, California, Effelsberg, Federal Republic of Germany, and Madrid, Spain. Data from the long baselines show that the A and B images contain core components with flux densities of 22±1 and 18±1 mJy, respectively. Data from the short Effelsberg-Madrid baseline suggest that additional correlated flux density, distributed over an angular scale of ≡20 mas, accompanies both cores. The observed brightness distributions of these cores are related by a linear magnification matrix, consistent with conservation of surface brightness, as expected for images produced by a transparent gravitational lens.

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