22 research outputs found
The ALADIN Interactive Sky Atlas
The Aladin interactive sky atlas, developed at CDS, is a service providing
simultaneous access to digitized images of the sky, astronomical catalogues,
and databases.
The driving motivation is to facilitate direct, visual comparison of
observational data at any wavelength with images of the optical sky, and with
reference catalogues.
The set of available sky images consists of the STScI Digitized Sky Surveys,
completed with high resolution images of crowded regions scanned at the MAMA
facility in Paris.
A Java WWW interface to the system is available at:
http://aladin.u-strasbg.fr/Comment: 8 pages, 3 Postscript figures; to be published in A&
The SIMBAD astronomical database
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. Simbad 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 d'Astrophysique de
Paris, and Observatoire de Bordeaux. When 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.
A WWW interface to Simbad is available at: http://simbad.u-strasbg.fr/SimbadComment: 14 pages, 5 Postscript figures; to be published in A&A
IVOA Recommendation: Data Model for Astronomical DataSet Characterisation
This document defines the high level metadata necessary to describe the
physical parameter space of observed or simulated astronomical data sets, such
as 2D-images, data cubes, X-ray event lists, IFU data, etc.. The
Characterisation data model is an abstraction which can be used to derive a
structured description of any relevant data and thus to facilitate its
discovery and scientific interpretation. The model aims at facilitating the
manipulation of heterogeneous data in any VO framework or portal. A VO
Characterisation instance can include descriptions of the data axes, the range
of coordinates covered by the data, and details of the data sampling and
resolution on each axis. These descriptions should be in terms of physical
variables, independent of instrumental signatures as far as possible.
Implementations of this model has been described in the IVOA Note available
at: http://www.ivoa.net/Documents/latest/ImplementationCharacterisation.html
Utypes derived from this version of the UML model are listed and commented in
the following IVOA Note:
http://www.ivoa.net/Documents/latest/UtypeListCharacterisationDM.html
An XML schema has been build up from the UML model and is available at:
http://www.ivoa.net/xml/Characterisation/Characterisation-v1.11.xsdComment: http://www.ivoa.ne
Acp et aci pour la reduction de données en imagerie astronomique multispectrale
Une technique de réduction de données astronomiques comme étape préliminaire à une classification d'images de galaxies lointaines est présentée. Le classifieur retenu est basé sur une modélisation markovienne causale en échelle sur le quadarbre. Ce papier présente les résultats encourageants obtenus par cette approche
IVOA Recommendation: Simple Spectral Access Protocol Version 1.1
The Simple Spectral Access (SSA) Protocol (SSAP) defines a uniform interface
to remotely discover and access one dimensional spectra. SSA is a member of an
integrated family of data access interfaces altogether comprising the Data
Access Layer (DAL) of the IVOA. SSA is based on a more general data model
capable of describing most tabular spectrophotometric data, including time
series and spectral energy distributions (SEDs) as well as 1-D spectra; however
the scope of the SSA interface as specified in this document is limited to
simple 1-D spectra, including simple aggregations of 1-D spectra. The form of
the SSA interface is simple: clients first query the global resource registry
to find services of interest and then issue a data discovery query to selected
services to determine what relevant data is available from each service; the
candidate datasets available are described uniformly in a VOTable format
document which is returned in response to the query. Finally, the client may
retrieve selected datasets for analysis. Spectrum datasets returned by an SSA
spectrum service may be either precomputed, archival datasets, or they may be
virtual data which is computed on the fly to respond to a client request.
Spectrum datasets may conform to a standard data model defined by SSA, or may
be native spectra with custom project-defined content. Spectra may be returned
in any of a number of standard data formats. Spectral data is generally stored
externally to the VO in a format specific to each spectral data collection;
currently there is no standard way to represent astronomical spectra, and
virtually every project does it differently. Hence spectra may be actively
mediated to the standard SSA-defined data model at access time by the service,
so that client analysis programs do not have to be familiar with the
idiosyncratic details of each data collection to be accessed
IVOA Recommendation: Observation Data Model Core Components and its Implementation in the Table Access Protocol Version 1.0
This document defines the core components of the Observation data model that
are necessary to perform data discovery when querying data centers for
observations of interest. It exposes use-cases to be carried out, explains the
model and provides guidelines for its implementation as a data access service
based on the Table Access Protocol (TAP). It aims at providing a simple model
easy to understand and to implement by data providers that wish to publish
their data into the Virtual Observatory. This interface integrates data
modeling and data access aspects in a single service and is named ObsTAP. It
will be referenced as such in the IVOA registries. There will be a separate
document to cover the full Observation data model. In this document, the
Observation Data Model Core Components (ObsCoreDM) defines the core components
of queryable metadata required for global discovery of observational data. It
is meant to allow a single query to be posed to TAP services at multiple sites
to perform global data discovery without having to understand the details of
the services present at each site. It defines a minimal set of basic metadata
and thus allows for a reasonable cost of implementation by data providers. The
combination of the ObsCoreDM with TAP is referred to as an ObsTAP service. As
with most of the VO Data Models, ObsCoreDM makes use of STC, Utypes, Units and
UCDs. The ObsCoreDM can be serialized as a VOTable. ObsCoreDM can make
reference to more complete data models such as ObsProvDM (the Observation
Provenance Data Model, to come), Characterisation DM, Spectrum DM or Simple
Spectral Line Data Model (SSLDM).Comment: About the IVOA: http://www.ivoa.net; editors: Doug Tody, Alberto
Micol, Daniel Durand, Mireille Louy