Francois Bonnarel

The SIMBAD astronomical database - The CDS reference database for astronomical objects

Simbad is the reference database for identification and bibliography of astronomical objects. It contains identifications, “basic data”, bibliography, and selected observational measurements for several million astronomical objects. u2029Simbad is developed and maintained by CDS, Strasbourg. Building the database contents is achieved with the help of several contributing institutes. Scanning the bibliography is the result of the collaboration of CDS with bibliographers in Observatoire de Paris (DASGAL), Institut dAstrophysique de Paris, and Observatoire de Bordeaux.u2029When selecting catalogues and tables for inclusion, priority is given to optimal multi-wavelength coverage of the database, and to support of research developments linked to large projects. In parallel, the systematic scanning of the bibliography reflects the diversity and general trends of astronomical research.u2029A WWW interface to Simbad is available at:u2029http://simbad.u-strasbg.fr/Simbad.

The Aladin Interactive Sky Atlas

The subject of this symposium, Multi-Wavelength Sky Surveys naturally invokes a discussion of methods of astronomical object identification and classification: Given a set of objects detected at a certain waveband, how does one integrate the new sources with previous data? The ALADIN system (Paillou et al. 1994) of the CDS is a software package designed to tackle this problem: It provides simultaneous access to digitized sky photographs, catalogs and databases to facilitate direct, visual comparison of user data with previously classified data, as well as automatic source extraction and calibration tools.

Entropy and astronomical data analysis: Perspectives from multiresolution analysis

The Maximum Entropy Method is well-known and widely used in image analysis in astronomy. In its standard form it presents certain drawbacks, such an underestimation of the photometry. Various renements of MEM have been proposed over the years. We review in this paper the main entropy functionals which have been proposed and discuss each of them. We dene, from a conceptual point of view, what a good denition of entropy should be in the framework of astronomical data processing. We show how a denition of multiscale entropy fullls these requirements. We show how multiscale entropy can be used for many applications, such as signal or image ltering, multi-channel data ltering, deconvolution, background fluctuation analysis, and astronomical image content analysis.

The SPECFIND V2.0 catalogue of radio cross-identifications and spectra - SPECFIND meets the Virtual Observatory

The new release of the SPECFIND radio cross-identification catalogue, nSPECFIND V2.0, is presented. It contains 107488 cross-identified objects with at least three radio sources observed at three independent frequencies. Compared to the previous release the number of entry radio catalogues is increased from 20 to 97 containing 115 tables. This large increase was only made possible by the development of four tools at CDS which use the standards and infrastructure of the Virtual Observatory (VO). This was done in the framework of the VO-TECH European Design Study of the Sixth Framework Program. We give an overview of the different classes of radio sources that a user can encounter. Due to the increase of frequency coverage of the input radio catalogues, this release demonstrates that the SPECFIND algorithm is able to detect spectral breaks around a frequency of ~1 GHz.

Introduction to the CFHT Legacy Survey final release (CFHTLS T0007)

The Canada-France-Hawaii Telescope Legacy Survey (CFHTLS) is a high impact scientific program which will see its final official release open to the world in 2012. That release will seal the legacy aspect of the survey which has already produced a large collection of scientific articles with topics ranging from cosmology to the Solar system. The survey core science was focused on dark energy and dark matter: the full realization of the scientific potential of the data set gathered between 2003 and 2009 with the MegaCam wide-field imager mounted at the CFHT prime focus is almost complete with the Supernovae Legacy Survey (SNLS) team preparing its third and last release (SNLS5), and the CFHTLenS team planning the release based around the cosmic shear survey later this year. While the data processing center TERAPIX offered to the CFHTLS scientific community regular releases over the course of the survey in its data acquisition phase (T0001-T0006), the final release took three years to refine in order to produce a pristine data collection photometrically calibrated at better than the percent both internally and externally over the total survey surface of 155 square degrees in all five photometric bands (u*, g’, r’, i’, z’). This final release, called T0007, benefits from the various advances in photometric calibration MegaCam has benefited through the joint effort between SNLS and CFHT to calibrate MegaCam at levels unexplored for an optical wide-field imager. T0007 stacks and catalogs produced by TERAPIX will be made available to the world at CADC while the CDS will offer a full integration of the release in its VO tools from VizieR to Aladin. The photometric redshifts have been produced to be released in phase with the survey. This proceeding is a general introduction to the survey and aims at presenting its final release in broad terms.

On-demand delivery of large compressed images in astronomy : Computational requirements

Performance results using wavelet and other multiresolution transforms are described. The roles of information content, resolution scale, and image capture noise, are discussed. Delivery systems for a range of large image repositories from areas which include medical, astronomy and graphic arts are described, as standalone systems for use on portable platforms, and client-server systems for use on the web.

Virtual observatory standards in action

Interoperability in Virtual Observatories is based on standards for interchange formats, and protocols. Using real science cases, we present example VO tools based on the AVO prototypes and the CDS services, which implement the new and emerging VO standards. We discuss how these standards, such as VOTable, UCDs and data models enable interoperability between software components, and provide efficient and flexible means for data access. We show how UCDs are used in catalogue filtering and selection of relevant columns. We also demonstrate a simple yet powerful method for accessing data from image archives, customized data sets and local data within a single environment.

Compression of grayscale scientific and medical image data

A review of issues in image compression is presented, with a strong focus on the wavelet transform and other closely related multiresolution transforms. The roles of information content, resolution scale, and image capture noise, are discussed. Experimental and practical results are reviewed.

The CDS Information Hub: Interoperability with Bibliography and Archives

The Centre de Données astronomiques de Strasbourg (CDS) has been collecting and distributing astronomical data for more than 25 years. It develops and maintains several reference databases, mainly an object database (SIMBAD), a catalogue database (VizieR) and an image database (Aladin). An important aspect consists also in developing links between these databases and other on-line services provided by the astronomical community.

The Centre de Données Astronomiques de Strasbourg

The activities of the Centre de Données astronomiques de Strasbourg (CDS) are reviewed. They include: SIMBAD, the reference database for the identification and bibliography of astronomical objects, the catalog service with the new VizieR Catalogue Browser developed as a joint effort by CDS and ESA/ESRIN and the WWW server. The future evolution of these services, including the distribution of the ALADIN interactive sky atlas, is also assessed.