GRAVITY: microarcsecond astrometry and deep interferometric imaging with the VLTI

Eisenhauer, F.; Perrin, Guillaume; Straubmeier, C.; Brandner, W.; Boehm, Armin; Cassaing, F.; Clénet, Y.; Dodds-Eden, K.; Eckart, A.; Fédou, P.; Gendron, É.; Genzel, R.; Gillessen, S.; Graeter, A.; Gueriau, C.; Hamaus, Nico; Haubois, X.; Haug, M.; Henning, Th.; Hippler, S.; Hofmann, R.; Hormuth, F.; Houairi, K.; Kellner, S.; Kervella, P.; Klein, Ralf; Kolmeder, J.; Laun, W.; Léna, Pierre; Lenzen, R.; Marteaud, M.; Meschke, Daniel; Naranjo, V.; Neumann, Uwe; Paumard, T.; Perger, M.; Perret, D.; Rabien, S.; Ramos, J.; Reess, J. M.; Rohloff, R.-R.; Rouan, D.; Rousset, G.; Ruyet, Bertrand Le; Schropp, M.; Talureau, B.; Thiel, Markus; Ziegleder, J.; Ziegler, D.

doi:10.1017/s1743921308018723

Cited by 5 publications

(3 citation statements)

References 3 publications

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“…The ASTRA upgrade of the Keck Interferometer will enable soon narrow-angle astrometry with an anticipated accuracy of ≈ 100 µas on star pairs with separations and brightness limits similar to PRIMA [32]. GRAVITY, an interferometric imager for the VLTI with astrometric capability, but with a total field of view of only 1.7 ′′ , is currently being developed and will enable 10 µas very narrow-angle astrometry on galactic center stars after 2012 [10]. The most important upcoming astrometric space missions, Gaia and SIM Lite, will not rely on real narrow-angle (dual star) astrometry, but shall be mentioned here because in particular SIM also addresses similar scientific questions as PRIMA and my thus be relevant to extent the time baseline for certain PRIMA targets.…”

Section: Narrow-angle Astrometry With Other Instrumentsmentioning

confidence: 99%

Exoplanet search with astrometry

Launhardt

2009

New Astronomy Reviews

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Searching for extrasolar planets by direct detection is extremely challenging for current instrumentation. Indirect methods, that measure the effect of a planet on its host star, are much more promising and have indeed led to the discovery of nearly all extrasolar systems known today. While the most successful method thus far is the radial velocity technique, new interferometric instruments like PRIMA at the VLTI will enable us to carry out astrometric measurements accurate enough to detect extrasolar planets and to determine all orbital parameters, including their orbit inclination and true mass. In this article I describe the narrow-angle astrometry technique, how it will be realized with PRIMA, what kind of planets we can find, and what kind of preparatory observations are required.Comment: 20 pages, 7 figures, contribution to the summerschool "Astrometry and Imaging with the Very Large Telescope Interferometer", 2 - 13 June, 2008, Keszthely, Hungar

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Section: Narrow-angle Astrometry With Other Instrumentsmentioning

confidence: 99%

Exoplanet search with astrometry

Launhardt

2009

New Astronomy Reviews

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“…In order to exploit the spectrum of the source, modern optical interferometers are paving the way for multi-wavelength imaging. Instruments such as AMBER (Petrov et al 2000), GRAVITY (Eisenhauer et al 2007) and MATISSE (Lopez et al 2009), can take measurements at multiple wavelength channels. This necessitates the progression of imaging techniques from monochromatic to hyperspectral case.…”

Section: Introductionmentioning

confidence: 99%

A regularized tri-linear approach for optical interferometric imaging

Birdi¹,

Repetti²,

Wiaux³

2017

Monthly Notices of the Royal Astronomical Society

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In the context of optical interferometry, only undersampled power spectrum and bispectrum data are accessible. It poses an ill-posed inverse problem for image recovery. Recently, a trilinear model was proposed for monochromatic imaging, leading to an alternated minimization problem. In that work, only a positivity constraint was considered, and the problem was solved by an approximated Gauss-Seidel method. In this paper, we propose to improve the approach on three fundamental aspects. First, we define the estimated image as a solution of a regularized minimization problem, promoting sparsity in a fixed dictionary using either an ℓ 1 or a (re)weighted-ℓ 1 regularization term. Secondly, we solve the resultant non-convex minimization problem using a block-coordinate forward-backward algorithm. This algorithm is able to deal both with smooth and non-smooth functions, and benefits from convergence guarantees even in a non-convex context. Finally, we generalize our model and algorithm to the hyperspectral case, promoting a joint sparsity prior through an ℓ 2,1 regularization term. We present simulation results, both for monochromatic and hyperspectral cases, to validate the proposed approach.

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“…Nowadays, modern OI is however polychromatic (see for instance AMBER [20], PIONIER [21], or VEGA [22]) and more powerful polychromatic instruments are in development (like MATISSE [23] and GRAVITY [24]). In such devices, interference fringes are simultaneously recorded in a number of wavelength channels that can reach several hundreds.…”

Section: Introductionmentioning

confidence: 99%

PAINTER: a spatiospectral image reconstruction algorithm for optical interferometry

et al. 2014

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Astronomical optical interferometers sample the Fourier transform of the intensity distribution of a source at the observation wavelength. Because of rapid perturbations caused by atmospheric turbulence, the phases of the complex Fourier samples (visibilities) cannot be directly exploited. Consequently, specific image reconstruction methods have been devised in the last few decades. Modern polychromatic optical interferometric instruments are now paving the way to multiwavelength imaging. This paper is devoted to the derivation of a spatio-spectral ("3D") image reconstruction algorithm, coined PAINTER (Polychromatic opticAl INTErferometric Reconstruction software). The algorithm relies on an iterative process, which alternates estimation of polychromatic images and of complex visibilities. The complex visibilities are not only estimated from squared moduli and closure phases, but also differential phases, which helps to better constrain the polychromatic reconstruction. Simulations on synthetic data illustrate the efficiency of the algorithm and in particular the relevance of injecting a differential phases model in the reconstruction.

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GRAVITY: microarcsecond astrometry and deep interferometric imaging with the VLTI

Cited by 5 publications

References 3 publications

Exoplanet search with astrometry

Exoplanet search with astrometry

A regularized tri-linear approach for optical interferometric imaging

PAINTER: a spatiospectral image reconstruction algorithm for optical interferometry

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