Mael Valais | Searcharxiv

arXiv2019

The solar survey at Pic du Midi: calibrated data and improved images

At Pic du Midi observatory we carry out a solar survey with images of the photosphere, prominences and corona. This survey, named CLIMSO (CLIchés Multiples du SOleil), is in the following spectral lines: Fe XIII corona (1.075 micron), H-alpha (656.3 nm) and He I (1.083 micron) prominences, H-alpha and Ca II (393.4 nm) photosphere. All frames cover 1.3 times the diameter of the Sun with an angular resolution approaching one arc second. The frame rate is one per minute per channel (weather permitting) for the prominences and chromosphere, and one per hour for the Fe XIII corona. This survey started in 2007 for the disk and prominences, and in 2015 for the corona. We have almost completed one solar cycle, and hope to cover several more, keeping the same wavelengths or adding others. Aims: Make the CLIMSO images easier to use and more profitable for the scientific community. Methods: Providing 'science-ready' data. We have improved the contrast capabilities of our coronagraphs, which now provide images of the Fe XIII corona, in addition to the previous spectral channels. We have also implemented an autoguiding system based on a diffractive Fresnel array for precise positioning of the Sun behind the coronagraphic masks. Results: The data (images and films) are publicly available and downloadable through virtual observatories and dedicated sites: e.g. http://climso.irap.omp.eu. For the H-alpha and and Ca II channels we calibrate the data into physical units, independent of atmospheric or instrumental conditions: we provide solar maps of spectral radiances inW m^-2 sr^-1 nm^-1. The instrumental improvements and the calibration process are presented in this paper.

astro-ph.IM↗

arXiv2015

Twist your logic with TouIST

SAT provers are powerful tools for solving real-sized logic problems, but using them requires solid programming knowledge and may be seen w.r.t.\ logic like assembly language w.r.t.\ programming. Something like a high level language was missing to ease various users to take benefit of these tools. {\sc \texttt {TouIST}}\ aims at filling this gap. It is devoted to propositional logic and its main features are 1) to offer a high-level logic langage for expressing succintly complex formulas (e.g.\ formulas describing Sudoku rules, planification problems,\ldots) and 2) to find models to these formulas by using the adequate powerful prover, which the user has no need to know about. It consists in a friendly interface that offers several syntactic facilities and which is connected with some sufficiently powerful provers allowing to automatically solve big instances of difficult problems (such as time-tables or Sudokus). It can interact with various provers: pure SAT solver but also SMT provers (SAT modulo theories - like linear theory of reals, etc) and thus may also be used by beginners for experiencing with pure propositional problems up to graduate students or even researchers for solving planification problems involving big sets of fluents and numerical constraints on them.

cs.CY↗