Showing papers by "Baptiste Cecconi published in 2015"

NenUFAR: Instrument description and science case

Abstract: NenuFAR is both a giant extension of the LOFAR and a large standalone instrument in the low-frequency range (10–85 MHz). It was designed in Nancay with national and international collaboration. Antenna radiators were modeled on the LWA antenna design whereas preamplifiers were designed in France. Antennas will be distributed in 96 mini-arrays of 19 dual-polarized elements, densely covering a disk of 400 m in diameter. A few mini-arrays are expected to lie at distances of 2–3 km. A silent control-command system was designed, and the computer dialog with LOFAR defined. Receivers will include the LOFAR backend, a local beamformer and a local correlator. NenuFAR is in construction in Nancay and it was recently granted by the SKA office the official label of SKA pathfinder. Its exploitation will expand the scope of LOFAR scientific studies as well as permit new studies, preparing for SKA science. The NenuFAR concept has many points in common with GURT (the Giant Ukrainian Radio Telescope), with which it shares some technical studies, an its exploitation will benefit from a coordination with UTR-2. We describe the instrument, technical developments and science case.

Planetary GIS and EuroPlanet-RI H2020

Abstract: Community building is a key part of VESPA [5], but also independently followed by other actors like ESA PSA [9]. Recently a workshop on Planetary GIS in broad sense and with particular reference to ESA data archives has been organized [10]. Such workshop has been strongly supported by ESA and the broad planetary community, both directly and through its official channel for Planetary Science archive science access and exploitation-related needs, the PSA User Group [11]. Its outcomes, also in terms of use case development, might be instrumental to VESPA GIS/VO future activities. References

In-flight calibration of STEREO-B/WAVES antenna system

Abstract: The STEREO/WAVES (SWAVES) experiment on board the two STEREO spacecraft (Solar Terrestrial Relations Observatory) launched on 25 October 2006 is dedicated to the measurement of the radio spectrum at frequencies between a few kilohertz and 16 MHz. The SWAVES antenna system consists of 6 m long orthogonal monopoles designed to measure the electric component of the radio waves. With this configuration direction finding of radio sources and polarimetry (analysis of the polarization state) of incident radio waves is possible. For the evaluation of the SWAVES data the receiving properties of the antennas, distorted by the radiation coupling with the spacecraft body and other onboard devices, have to be known accurately. In the present context, these properties are described by the antenna effective length vectors. We present the results of an in-flight calibration of the SWAVES antennas using the observations of the nonthermal terrestrial auroral kilometric radiation (AKR) during STEREO roll maneuvers in an early stage of the mission. A least squares method combined with a genetic algorithm was applied to find the effective length vectors of the STEREO Behind (STEREO-B)/WAVES antennas in a quasi-static frequency range ($L_{antenna} \ll \lambda_{wave}$) which fit best to the model and observed AKR intensity profiles. The obtained results confirm the former SWAVES antenna analysis by rheometry and numerical simulations. A final set of antenna parameters is recommended as a basis for evaluations of the SWAVES data.

The VO: A Powerful Tool for Global Astronomy

Abstract: Since its inception in the early 2000's, the Virtual Observatory (VO), developed as a collaboration of many national and international projects, has become a major factor in the discovery and dissemination of astronomical information worldwide. The International Virtual Observatory Alliance (IVOA) has been coordinating all these efforts worldwide to ensure a common VO framework that enables transparent access to and interoperability of astronomy resources (data and software) around the world. The VO is not a magic solution to all astronomy data management challenges but it does bring useful solutions in many areas borne out by the fact that VO interfaces are broadly found in astronomy's major data centres and projects worldwide. Astronomy data centres have been building VO services on top of their existing data services to increase interoperability with other VO-compliant data resources to take advantage of the continuous and increasing development of VO applications. VO applications have made multi-instrument and multi-wavelength science, a difficult and fruitful part of astronomy, somewhat easier. More recently, several major new astronomy projects have been directly adopting VO standards to build their data management infrastructure, giving birth to ‘VO built-in' archives. Embracing the VO framework from the beginning brings the double gain of not needing to reinvent the wheel and ensuring from the start interoperability with other astronomy VO resources. Some of the IVOA standards are also starting to be used by neighbour disciplines like planetary sciences. There is still quite a lot to be done on the VO, in particular tackling the upcoming big data challenge and how to find interoperable solutions to the new data analysis paradigm of bringing and running the software close to the data. We report on the current status and also desire to encourage others to adopt VO technology and engage them in the effort of developing the VO. Thus, we wish to ensure that the VO standards fit new astronomy projects requirements and needs.

VESPA: Developing the Planetary Science Virtual Observatory in H2020

Abstract: In the frame of the Europlanet-RI program, a prototype Virtual Observatory dedicated to Planetary Science has been set up. Most of the activity was dedicated to the definition of standards to handle data in this field. The aim was to facilitate searches in big archives as well as sparse databases, to make on-line data access and visualization possible, and to allow small data providers to make their data available in an interoperable environment with minimum effort. This system makes intensive use of studies and developments led in Astronomy (IVOA), Solar Science (HELIO), and space archive services (IPDA). A general standard has been devised to handle the specific complexity of Planetary Science, e.g. in terms of measurement types and coordinate frames [1]. A procedure has been identified to install small data services, and several hands-on sessions have been organized already. A specific client (VESPA) has been developed at VO-Paris (http://vespa.obspm.fr), using a resolver for target names. Selected data can be sent to VO visualization tools such as TOPCAT or Aladin though the SAMP protocol. The Europlanet H2020 program started in Sept 2015 will provide support to new data services in Europe (30 to 50 expected), and focus on the improvement of the infrastructure. Future steps will include the development of a connection between the VO world and GIS tools, and integration of heliophysics, planetary plasma and reference spectroscopic data. The Europlanet H2020 project is funded by the European Commission under the H2020 Program, grant 654208. [1] Erard et al Astron & Comp 2014

Planetary Sciences Interoperability at VO Paris Data Centre

Abstract: P. Le Sidaner(1), J. Aboudarham (2), M. Birlan (3), J. Berthier (3), D. Briot (4), X. Bonnin (2), B. Cecconi (2) , C. Chauvin (1), S. Erard (2), F. Henry (2), L. Lamy (2), M. Mancini (5), J. Normand (3), M. Popescu (3), F. Roques (2), R. Savalle (1), J. Schneider (5), A. Shih (1), W. Thuillot (3), S. Vinatier (2) (1) DIO-VO, UMS2201 Obs. Paris/CNRS, Fr (pierre.lesidaner@obspm.fr), (2) LESIA, Obs. Paris/CNRS/UPMC/U. ParisDiderot, Fr, (3) IMCCE/Obs. Paris/CNRS, Fr, (4) GEPI, Obs. Paris/CNRS/U. Paris 7, Fr, (5)LUTH, Obs. Paris/CNRS/U. Paris-Diderot, Fr

Updated modeling of Io and non-Io Radio Auroral Emissions of Jupiter

Abstract: The radio auroral emissions produced by the Jupiter’s magnetosphere between a few kHz and 40MHz, the most intense of our Solar System, are known since half a century, but they still drive many questions, and their deepened study is one of the main aim of the JUNO missions (arrival in July 2016). Jovian auroral radio emissions are thought to be produced through the Cyclotron Maser Instability (CMI), from non-maxwellian weakly relativistic electrons gyrating along high-latitude magnetic fields lines (Zarka, 1998). These emissions divide in different spectral components, driven or not by the moon Io. The origin and the relationship between kilometric, hectometric and decametric non-Io emissions in particular remains poorly understood. To investigate these emissions, we simulated numerical dynamic spectra with the most recent version of the ExPRES code Exoplanetary and Planetary Radio Emission Simulator, available at http://maser.obspm.fr already used to successfully model Io decametric and Saturn’s kilometric arcshaped emissions (Hess et al., 2008, Lamy et al., 2008) and predict exoplanetary radio emissions (Hess et al., 2011). Such simulations bring direct constraints on the locus of active magnetic field lines and on the nature of CMI-unstable electrons (Hess et al., submitted). We validated the new theoretical calculation of the beaming angle used by ExPRES, which now includes refraction at the source. We then built updated simulations of Io and non-Io emissions which were compared to the radio observations acquired by the Cassini spacecraft (Jupiter flyby in 2000) and the Nançay decameter array (routines observations of Jupiter). 1. Figure Figure 1: (a, b, c) Dynamic spectra of typical IoJupiter arcs observed by Wind/Waves and the Nancay decameter array. (d, e, f) Dynamic spectra of IoJupiter emissions for the same t-f intervals as in Figures 3a, 3b, and 3c, simulated by the ExPRES code using actual observing geometries (Black arcs are generated in the northern hemisphere and grey in the southern one. Labels in italics indicate weak or unobserved arcs. EPSC Abstracts Vol. 10, EPSC2015-830, 2015 European Planetary Science Congress 2015 c © Author(s) 2015 EPSC European Planetary Science Congress