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Authors: M. Carbillet, S. Correia, P. Boccacci, and M. Bertero
Abstract: This presentation reports the status of our study concerning the imaging properties of the Large Binocular Tele- scope (LBT) interferometer, and namely the effect of limited angular coverage and partial adaptive optics (AO) correction. The limitation in angular coverage, together with the correlated problem of angular smearing due to time-averaging of the interferometric images, is investigated for relevant cases depending on the declination of the observed object. Results are encouraging even in case of incomplete coverage. Partial AO-correction can result in a wide range of image quality, but can also create significative differences within a same field-of-view, especially between a suitable reference star to be used for post-observation multiple deconvolution and the observed object. Our study deals with both the problem of space-variance of the AO-corrected point-spread function, and that of global quality of the AO-correction. Uniformity, rather than global quality, is found to be the key-problem. After considering the single-conjugate AO case, we reach to some conclusions for the more interesting, and actually wide-field, case implying multi-conjugate AO. The whole study is performed on different types of object, from binary stars to diffuse objects, and a combined one with a high-dynamic range.

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Posted by: admin, on 11/1/2006, in category "2002"
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Authors: S. Correia, M. Carbillet, P. Boccacci, M. Bertero, and L. Fini
Abstract: The Sofware Package AIRY (Astronomical Image Restoration in interferometrY) described in this paper is designed for simulated and/or multiple deconvolution of interferometric images. It was conceived for application to the Large Binocular Telescope (LBT), but can also be used for future interferometers of the same class. AIRY is modular, IDL-based, and designed to be use together with the CAOS (Code for Adaptative Optics Systems) Application Builder. As concers mulpiple deconvolution AIRY includes an implementation of the method OS-EM (Ordered Subsets-Expectation Maximization) which is an accelerated version of the Lucy-Richardson method. After a description of the structure and modules of the software package, it use is illustrated with a few applications. In particular the intrinsic performance of the implemented restoration method is explored in the case of binary stars of different angular separations and magnitude differences, as well as in the case of a diffuse object. The possibility of obtaining super-resolved images of unresolved binary stars is also demonstrated.

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Posted by: admin, on 11/1/2006, in category "2002"
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Authors: M. Carbillet, S. Correia, P. Boccacci, and M. Bertero
Abstract: The Sofware Package AIRY (Astronomical Image Restoration in interferometrY), designed for multiple deconvolution of interferometric images and presented in the previous paper, is applied to the investigation of the imaging properties of the Large Binocular Telescope. For our analysis we use a simulated object consisting of a core binary star surrounded by a circumbinary ring "à la GG Tau". We first investigate the effect of angular coverage (linked to the problem of time-averaging smearing of the interferometric images), which depends on the declination of the observed object. The result are encouraging because we find that, even in the case of incomplete coverage, satisfactory estimations of the relevant astronomical parameters may be obtained. We then study two different adaptive optics (AO) correction schemes, namely classical AO and multi-conjugate AO. We find that the uniformity of the point spread functions (PSF) over the fiel-of-view, rather then the absolute quality of the AO-corrected reference PSFs, is fundamental for the quality of the restored images.

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Posted by: admin, on 11/1/2006, in category "2002"
Views: this article has been read 9896 times