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See detail8ème Cours de Mécanique Analytique II (2016-17), Bac3 phys, Master 1 Sc. Sp.
Surdej, Jean ULg

Learning material (2016)

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See detail7ème Cours de Mécanique Analytique II (2016-17), Bac3 phys, Master 1 Sc. Sp.
Surdej, Jean ULg

Learning material (2016)

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See detail6ème Cours de Mécanique Analytique II (2016-17), Bac3 phys, Master 1 Sc. Sp.
Surdej, Jean ULg

Learning material (2016)

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See detailCours No 3: Astrophysique et Techniques Spatiales: Ingés aéro/ Ingés Phys 2016-2017 (Fichier PDF + vidéos: mov)
Surdej, Jean ULg

Learning material (2016)

In this course of Astronomy and space techniques, we introduce all the necessary concepts that enable us to understand basic observational data as well as modern ground-based and space telescopes and ... [more ▼]

In this course of Astronomy and space techniques, we introduce all the necessary concepts that enable us to understand basic observational data as well as modern ground-based and space telescopes and their instrumentation. This course has been designed for future engineers willing to understand and communicate with other people basic concepts of astronomy as well as to those wishing to pursue more specialized studies in astrophysics (cf. end-of-year thesis oriented towards astrophysics, master in space sciences, PhD in astrophysics, ...) or a future career in this field. In the first part of this course, we present the main discoveries in astrophysics already known by the antique greek astronomers, including an introduction to the different spherical coordinate systems and to photometry. [less ▲]

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See detailCours No 2: Astrophysique et Techniques Spatiales: Ingés aéro/ Ingés Phys 2016-2017 (Fichier PDF + vidéos: mov)
Surdej, Jean ULg

Learning material (2016)

In this course of Astronomy and space techniques, we introduce all the necessary concepts that enable us to understand basic observational data as well as modern ground-based and space telescopes and ... [more ▼]

In this course of Astronomy and space techniques, we introduce all the necessary concepts that enable us to understand basic observational data as well as modern ground-based and space telescopes and their instrumentation. This course has been designed for future engineers willing to understand and communicate with other people basic concepts of astronomy as well as to those wishing to pursue more specialized studies in astrophysics (cf. end-of-year thesis oriented towards astrophysics, master in space sciences, PhD in astrophysics, ...) or a future career in this field. In the first part of this course, we present the main discoveries in astrophysics already known by the antique greek astronomers, including an introduction to the different spherical coordinate systems and to photometry. [less ▲]

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See detailCours No 1: Astrophysique et Techniques Spatiales: Ingés aéro/ Ingés Phys 2016-2017 (Fichier PDF + vidéos: mov)
Surdej, Jean ULg

Learning material (2016)

In this course of Astronomy and space techniques, we introduce all the necessary concepts that enable us to understand basic observational data as well as modern ground-based and space telescopes and ... [more ▼]

In this course of Astronomy and space techniques, we introduce all the necessary concepts that enable us to understand basic observational data as well as modern ground-based and space telescopes and their instrumentation. This course has been designed for future engineers willing to understand and communicate with other people basic concepts of astronomy as well as to those wishing to pursue more specialized studies in astrophysics (cf. end-of-year thesis oriented towards astrophysics, master in space sciences, PhD in astrophysics, ...) or a future career in this field. In the first part of this course, we present the main discoveries in astrophysics already known by the antique greek astronomers, including an introduction to the different spherical coordinate systems and to photometry. [less ▲]

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See detailSmart co-phasing system for segmented mirror telescopes
Simar, Juan Felipe ULg; Stockman, Yvan ULg; Surdej, Jean ULg

in SPIE 9906, Ground-based and Airborne Telescopes VI (2016, July 27)

Space observations of fainter and more distant astronomical objects constantly require telescope primary mirrors with a larger size. The diameter of monolithic primary mirrors is limited to 10 m because ... [more ▼]

Space observations of fainter and more distant astronomical objects constantly require telescope primary mirrors with a larger size. The diameter of monolithic primary mirrors is limited to 10 m because of manufacturing and logistics limitations. For space telescopes, monolithic primary mirrors are limited to less than 5 m due to fairing capacity. Segmented primary mirrors thus constitute an alternative solution to deal with the steadily increase of the primary mirror size. The optical path difference between the individual segments must be close to zero (few nm) in order to be diffraction limited over the full telescope aperture. In this paper a new system that may co-phase 7 segments at once with the light of a star and without artificial one is proposed. First the measuring methods and feedback system is explained, then the breadboard setup is presented and the results are analyzed and discussed, finally a comparison with Keck telescope is performed. This system can be adapted in order to be used in the co-phasing system of future segmented mirrors, its dynamic range starts from several hundred of microns till some tenths of nanometers [less ▲]

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See detailSmart co-phasing system for segmented mirror telescopes
Simar, Juan Felipe ULg; Stockman, Yvan ULg; Surdej, Jean ULg

Poster (2016, June 30)

One of the main challenges in space observations is to observe always fainter and more compact objects. This can be achieved by increasing the telescope diameters. So, increasing the primary mirror ... [more ▼]

One of the main challenges in space observations is to observe always fainter and more compact objects. This can be achieved by increasing the telescope diameters. So, increasing the primary mirror diameters of the telescopes is the challenge solution but it is technically impossible to manufacture monolithic mirrors larger than 10m in diameter. The use of segmented mirrors thus becomes mandatory. This paper describes the results of a light co-phasing setup mounted in laboratory. This setup is able to correct a piston from 200μm to 15 nm based on coarse (200μm to 300nm) and fine (300nm to 15nm) measurement methods. Both measurements are then chained in a feedback system in order to completely co-phase and keep the segments aligned. [less ▲]

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See detailVortex Image Processing (VIP) package for high-contrast direct imaging
Gómez González, Carlos ULg; Absil, Olivier ULg; Wertz, Olivier ULg et al

Poster (2016, May 16)

VIP is a Python instrument-agnostic toolbox featuring a flexible framework for reproducible and robust data reduction. VIP currently supports three high-contrast imaging observational techniques: angular ... [more ▼]

VIP is a Python instrument-agnostic toolbox featuring a flexible framework for reproducible and robust data reduction. VIP currently supports three high-contrast imaging observational techniques: angular, reference-star and multi-spectral differential imaging. The code can be downloaded from our git repository on Github: http://github.com/vortex-exoplanet/VIP [less ▲]

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Peer Reviewed
See detailLow-rank plus sparse decomposition for exoplanet detection in direct-imaging ADI sequences. The LLSG algorithm
Gómez González, Carlos ULg; Absil, Olivier ULg; Absil, P.-A. et al

in Astronomy and Astrophysics (2016), 589

Context. Data processing constitutes a critical component of high-contrast exoplanet imaging. Its role is almost as important as the choice of a coronagraph or a wavefront control system, and it is ... [more ▼]

Context. Data processing constitutes a critical component of high-contrast exoplanet imaging. Its role is almost as important as the choice of a coronagraph or a wavefront control system, and it is intertwined with the chosen observing strategy. Among the data processing techniques for angular differential imaging (ADI), the most recent is the family of principal component analysis (PCA) based algorithms. It is a widely used statistical tool developed during the first half of the past century. PCA serves, in this case, as a subspace projection technique for constructing a reference point spread function (PSF) that can be subtracted from the science data for boosting the detectability of potential companions present in the data. Unfortunately, when building this reference PSF from the science data itself, PCA comes with certain limitations such as the sensitivity of the lower dimensional orthogonal subspace to non-Gaussian noise. <BR /> Aims: Inspired by recent advances in machine learning algorithms such as robust PCA, we aim to propose a localized subspace projection technique that surpasses current PCA-based post-processing algorithms in terms of the detectability of companions at near real-time speed, a quality that will be useful for future direct imaging surveys. <BR /> Methods: We used randomized low-rank approximation methods recently proposed in the machine learning literature, coupled with entry-wise thresholding to decompose an ADI image sequence locally into low-rank, sparse, and Gaussian noise components (LLSG). This local three-term decomposition separates the starlight and the associated speckle noise from the planetary signal, which mostly remains in the sparse term. We tested the performance of our new algorithm on a long ADI sequence obtained on β Pictoris with VLT/NACO. <BR /> Results: Compared to a standard PCA approach, LLSG decomposition reaches a higher signal-to-noise ratio and has an overall better performance in the receiver operating characteristic space. This three-term decomposition brings a detectability boost compared to the full-frame standard PCA approach, especially in the small inner working angle region where complex speckle noise prevents PCA from discerning true companions from noise. [less ▲]

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See detailLarger and faster: revised properties and a shorter orbital period for the WASP-57 planetary system from a pro-am collaboration
Southworth, John; Mancini, L.; Tregloan-Reed, J. et al

in Monthly Notices of the Royal Astronomical Society (2015), 454

Transits in the WASP-57 planetary system have been found to occur half an hour earlier than expected. We present 10 transit light curves from amateur telescopes, on which this discovery was based, 13 ... [more ▼]

Transits in the WASP-57 planetary system have been found to occur half an hour earlier than expected. We present 10 transit light curves from amateur telescopes, on which this discovery was based, 13 transit light curves from professional facilities which confirm and refine this finding, and high-resolution imaging which show no evidence for nearby companions. We use these data to determine a new and precise orbital ephemeris, and measure the physical properties of the system. Our revised orbital period is 4.5 s shorter than found from the discovery data alone, which explains the early occurrence of the transits. We also find both the star and planet to be larger and less massive than previously thought. The measured mass and radius of the planet are now consistent with theoretical models of gas giants containing no heavy-element core, as expected for the subsolar metallicity of the host star. Two transits were observed simultaneously in four passbands. We use the resulting light curves to measure the planet's radius as a function of wavelength, finding that our data are sufficient in principle but not in practise to constrain its atmospheric properties. We conclude with a discussion of the current and future status of transmission photometry studies for probing the atmospheres of gas-giant transiting planets. [less ▲]

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