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Proceedings Paper

Phase referencing in optical interferometry
Author(s): Mercedes E. Filho; Paulo Garcia; Gilles Duvert; Gaspard Duchene; Eric Thiebaut; John Young; Olivier Absil; Jean-Phillipe Berger; Thomas Beckert; Sebastian Hoenig; Dieter Schertl; Gerd Weigelt; Leonardo Testi; Eric Tatuli; Virginie Borkowski; Michaël de Becker; Jean Surdej; Bernard Aringer; Joseph Hron; Thomas Lebzelter; Andrea Chiavassa; Romano Corradi; Tim Harries
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Paper Abstract

One of the aims of next generation optical interferometric instrumentation is to be able to make use of information contained in the visibility phase to construct high dynamic range images. Radio and optical interferometry are at the two extremes of phase corruption by the atmosphere. While in radio it is possible to obtain calibrated phases for the science objects, in the optical this is currently not possible. Instead, optical interferometry has relied on closure phase techniques to produce images. Such techniques allow only to achieve modest dynamic ranges. However, with high contrast objects, for faint targets or when structure detail is needed, phase referencing techniques as used in radio interferometry, should theoretically achieve higher dynamic ranges for the same number of telescopes. Our approach is not to provide evidence either for or against the hypothesis that phase referenced imaging gives better dynamic range than closure phase imaging. Instead we wish to explore the potential of this technique for future optical interferometry and also because image reconstruction in the optical using phase referencing techniques has only been performed with limited success. We have generated simulated, noisy, complex visibility data, analogous to the signal produced in radio interferometers, using the VLTI as a template. We proceeded with image reconstruction using the radio image reconstruction algorithms contained in aips imagr (clean algorithm). Our results show that image reconstruction is successful in most of our science cases, yielding images with a 4 milliarcsecond resolution in K band. We have also investigated the number of target candidates for optical phase referencing. Using the 2MASS point source catalog, we show that there are several hundred objects with phase reference sources less than 30 arcseconds away, allowing to apply this technique.

Paper Details

Date Published: 28 July 2008
PDF: 12 pages
Proc. SPIE 7013, Optical and Infrared Interferometry, 70131F (28 July 2008); doi: 10.1117/12.787908
Show Author Affiliations
Mercedes E. Filho, Ctr. de Astrofisica, Univ. do Porto (Portugal)
Paulo Garcia, Ctr. de Astrofisica, Univ. do Porto (Portugal)
Univ. do Porto (Portugal)
Gilles Duvert, Lab. d'Astrophysique, Observatoire de Grenoble (France)
Gaspard Duchene, Univ. of California, Berkeley (United States)
Eric Thiebaut, Observatoire de Lyon (France)
John Young, Cavendish Lab. (United Kingdom)
Olivier Absil, Univ. Joseph Fourier, CNRS, Lab. d'Astrophysique de Grenoble (France)
Jean-Phillipe Berger, Univ. Joseph Fourier, CNRS, Lab. d'Astrophysique de Grenoble (France)
Thomas Beckert, Max-Planck Institute for Radioastronomy (Germany)
Sebastian Hoenig, Max-Planck Institute for Radioastronomy (Germany)
Dieter Schertl, Max-Planck Institute for Radioastronomy (Germany)
Gerd Weigelt, Max-Planck Institute for Radioastronomy (Germany)
Leonardo Testi, INAF, Osservatorio di Astrofisica di Arcetri (Italy)
Eric Tatuli, INAF, Osservatorio di Astrofisica di Arcetri (Italy)
Virginie Borkowski, Institute of Astrophysics and Geophysics (Belgium)
Michaël de Becker, Institute of Astrophysics and Geophysics (Belgium)
Jean Surdej, Institute of Astrophysics and Geophysics (Belgium)
Bernard Aringer, Institute of Astrophysics, Univ. of Wien (Austria)
Joseph Hron, Institute of Astrophysics, Univ. of Wien (Austria)
Thomas Lebzelter, Institute of Astrophysics, Univ. of Wien (Austria)
Andrea Chiavassa, Astrophysique du Languedoc (France)
Romano Corradi, Astrophysique du Languedoc (France)
Tim Harries, Univ. of Exeter (United Kingdom)

Published in SPIE Proceedings Vol. 7013:
Optical and Infrared Interferometry
Markus Schöller; William C. Danchi; Françoise Delplancke, Editor(s)

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