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Abstract: This course describes the data reduction process of the AMBER instrument, the three beam-recombiner of the very large telescope interferometer (VLTI). In body of this paper, we develop its principles from a theoretical point of view and we illustrate the main points with examples taken from the practical AMBER data reduction session given during school. The detailed practical application making use of the ESO gasgano tool is then presented. In this lecture, we particularly emphasize what the AMBER data reduction process is (i) a fit of the interferogram in the detector plane, (ii) using an a priori calibration of the instrument, where (iii) the complex visibility of the source is estimated from a least-square determination of a linear inverse problem, and where (iv) the derived AMBER observables are the squared visibility, the closure phase, and the spectral differential phase. [Copyright &y& Elsevier]

Future and planned optical long-baseline interferometers will allow rapid spectro-imaging at high angular resolution. A non-homothetic Fizeau instrument using optical fibres is one of the most promising concepts because it combines good sensitivity and high spectral resolution capabilities. However, when increasing the number of input telescopes, one critical issue is the design of the beam recombination scheme, at the heart of the instrument. Extending our previous analysis on the multi-axial ‘all-in-one’ recombination, where the beams are mixed all together, in this paper we tackle the possibility of reducing the number of pixels that are coding the fringes by compressing the pupil plane from a partially redundant output pupils configuration. Shrinking the number of pixels, which drastically increases with the number of recombined telescopes, is indeed a key issue that enables one to reach a higher limiting magnitude, but also allows one to lower the required spectral resolution and fasten the fringe reading process. By means of numerical simulations, we study the performances of existing estimators of the squared visibility with respect to the compression process. We show that not only does the model-based estimator lead to better signal-to-noise ratio (S/N) performances than the Fourier ones, but above all it is the only one that prevents the introduction of baseline mixing biases in the visibilities as the pupil plane compression rate increases. Furthermore, we show that moderate compression allows one to keep the S/N of the visibilities unaffected. In light of these conclusions, we propose an optimized pupil arrangement for six- and eight-beam recombiners. [ABSTRACT FROM AUTHOR]

There are several solutions to code the signal arising from optical long-baseline multi-aperture interferometers. In this paper, we focus on the non-homothetic spatial coding scheme (multi-axial) with the fringe pattern coded along one dimension on one detector (all-in-one). After describing the physical principles governing single-mode interferometers using that sort of recombination scheme, we analyse two different existing methods that measure the source visibility. The first technique, the so-called Fourier estimator, consists of integrating the high-frequency peak of the power spectral density of the interferogram. The second method, the so-called model-based estimator, has been specifically developed for the Astronomical Multi-BEam combineR (AMBER) instrument of the Very Large Telescope Interferometer (VLTI) and deals with directly modelling the interferogram recorded on the detector. Performances of both estimators are computed in terms of the signal-to-noise ratio (S/N) of the visibility, assuming that the interferograms are perturbed by photon and detector noises. Theoretical expressions of the visibility S/N are provided, validated through numerical computations and then compared. We show that the model-based estimator offers up to 5 times better performances than the Fourier one. [ABSTRACT FROM AUTHOR]

We present a review of the interplay between the evolution of circumstellar disks and the formation of planets, both from the perspective of theoretical models and dedicated observations. Based on this, we identify and discuss fundamental questions concerning the formation and evolution of circumstellar disks and planets which can be addressed in the near future with optical and infrared long-baseline interferometers. Furthermore, the importance of complementary observations with long-baseline (sub)millimeter interferometers and high-sensitivity infrared observations is outlined. [ABSTRACT FROM AUTHOR]

Aims. We study the sub-AU-scale circumstellar environment of the Herbig Ae star HD 144432 with near-infrared VLTI/AMBER observations to investigate the structure of its inner dust disk. Methods. The interferometric observations were carried out with the AMBER instrument in the H and K band. We interpret the measured H- and K-band visibilities, the near- and mid-infrared visibilities from the literature, and the spectral energy distribution (SED) of HD 144432 by using geometric ring models and ring-shaped temperature-gradient disk models with power-law temperature distributions. Results. We derive a K-band ring-fit radius of 0.17 ± 0.01 AU and an H-band radius of 0.18 ± 0.01 AU (for a distance of 145 pc). This measured K-band radius of ∼0.17 AU lies in the range between the dust sublimation radius of ∼0.13 AU (predicted for a dust sublimation temperature of 1500 K and gray dust) and the prediction of models including backwarming (∼0.27 AU). We find that an additional extended halo component is required in both the geometric and temperature-gradient modeling. In the best-fit temperaturegradient model, the disk consists of two components. The inner part of the disk is a thin ring with an inner radius of ∼0.21 AU, a temperature of ∼1600 K, and a ring thickness ∼0.02 AU. The outer part extends from ∼1 AU to ∼10 AU with an inner temperature of ∼400 K. We find that the disk is nearly face-on with an inclination angle of <28°. Conclusions. Our temperature-gradient modeling suggests that the near-infrared excess is dominated by emission from a narrow, bright rim located at the dust sublimation radius, while an extended halo component contributes ∼6% to the total flux at 2 μm. The mid-infrared model emission has a two-component structure with ∼20% of the flux originating from the inner ring and the rest from the outer parts. This two-component structure is indicative of a disk gap, which is possibly caused by the shadow of a puffed-up inner rim. [ABSTRACT FROM AUTHOR]

Purpose. The present three pilot studies assessed the effectiveness of verbal instructions, presented automatically through simple technology, in helping persons with mild-to-moderate Alzheimer's disease recapture basic daily activities. The activities were morning bathroom routine, dressing, and table-setting. Method. The studies that focused on morning bathroom routine and on table-setting included three participants each, while the study that focused on dressing involved four participants. A non-concurrent multiple baseline design across participants was used for each study. The instructions and technology were available only during the intervention phases. Results. Data showed that the intervention strategy involving verbal instructions for the single activity steps presented automatically through technology was effective in helping all participants on each of the activities. The participants' mean percentages of correct steps across activities raised from 13 - 54 during the baseline periods to above 80 or 90 during the intervention periods. Conclusions. The results suggest that the intervention strategy reported may represent a suitable approach for helping persons with mild or moderate Alzheimer's disease to recapture basic daily activities. New research should target other activities and check maintenance and generalization issues. [ABSTRACT FROM AUTHOR]