Federation and Fusion of astronomical information Daniel Egret & Françoise Genova, CDS, Strasbourg Standards and tools for the Virtual Observatories

Garching VO Conference - June Diversity and Heterogeneity Specific VO scenarios imply to: n cross-match surveys, mission logs, observational catalogues, personal files n collect all pieces of information about an object or a set of objects n build samples of astronomical objects n discover rare objects in a multiwavelength space…

Garching VO Conference - June A specificity of the VO will be to effectively collect data from several diverse and distributed systems: hence the need for data federation and data fusion.

Garching VO Conference - June Definitions (1): Data Federation nJoining data relevant to the same objects or phenomena, n extracted from archives and databases, n possibly heterogeneous and distributed.

Garching VO Conference - June Definitions (2): Data Fusion l... implies to go one step deeperin the semantic description of the data l so that relevant pieces of information can be immediately compared, merged and/or correlated.

Garching VO Conference - June Outline l We present an overview of current solutions, with examples mainly taken from CDS services and tools : n Interoperability tools for data federation n Metadata dictionaries and standards for data fusion

Garching VO Conference - June Solving a complex query may typically require many steps: n Step 1 : resource discovery : what are the resources that can provide relevant information ? n Step 2 : resource locator : address and query syntax of the resource ? n Step 3 : query processing n Step 4 : presentation of the federated answer (datasets, number of records, pages of information, documentation,...) n Step 5 : data fusion n Step 6 : data visualization.

Garching VO Conference - June Resource discovery l On-line archives: SDSS, EIS, 2MASS l Object databases : SIMBAD, NED l Federated database: VizieR l Data centres ; AstroBrowse ; l Resource lists: AstroWeb

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Garching VO Conference - June  Generic resource discovery services will be an essential part of the VO.

Garching VO Conference - June Resource locator Locating the most recent (and closest if mirrors) version of archive/survey/table/… l GLU dictionary : description of resource location and query language; astronomy service registry. l Web services (such as Universal Description, Discovery and Integration)... n but astronomy specific modules still needed.

Garching VO Conference - June Example of GLU records describing Aladin service

Garching VO Conference - June GLU records for SkyView

Garching VO Conference - June Query processing Submitting queries to several distributed heterogeneous systems n AstroBrowse, AstroGLU, ISAIA n Simple Cone search (NVO) n Distributed system vs central node ? n New protocols : SOAP and WSDL n New formats: XML / RPC  Towards distributed (data grid) query processing for the Virtual Observatory.

Garching VO Conference - June Interoperability l A central aspect of the VO is the interoperability : heterogeneous databases and information services do exchange information as part of the query processing. (see talk by Mark Allen)

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Garching VO Conference - June Data presentation Response from distributed queries: l Summary information and dataset descriptions l Providing multiple responses n showing all results n in normalized form (e.g. units…) n using standard format (FITS, XML) n together with documentation files.

Garching VO Conference - June Simbad

Garching VO Conference - June VizieR

Garching VO Conference - June Example of Vizier global search

Garching VO Conference - June Data Fusion l Needs a semantic description n VOTable format (XML) n and UCD (see poster by Sebastien Derriere) l Example of Aladin tools: n overlays, colour composition, n astrometric registration and resampling n see poster by Fernique et al.

Garching VO Conference - June The ALADIN data integrator NGC 5236 l DSS image l HST observation FOV l SIMBAD and NED l GSC, USNO A2 l IUE observations

Garching VO Conference - June GLU system

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Garching VO Conference - June Aladin: Chandra contours

Garching VO Conference - June Aladin: colour composition

Garching VO Conference - June MASS combined images

Garching VO Conference - June ( see poster by Louys et al.)

Garching VO Conference - June Multi-wavelength cross-identification lMulti-wavelength cross-identifications, at a massive scale, using reference surveys are a key to data fusion. l Interoperable data-mining services.

Garching VO Conference - June Data Visualization l Spectral Energy Distribution (NED) l Image contours (ALADIN) l Sky maps l Histograms l Colour-magnitude diagrams

Garching VO Conference - June NED: Spectral Energy distribution

Garching VO Conference - June Looking at the Virtual Sky

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Garching VO Conference - June Aladin : All sky

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Garching VO Conference - June Conclusion At the end of the current VO deployment, we expect VO portals to provide: l resource discovery tools l full documentation and library l metadata dictionaries l normalized query engines.  Data and Information fusion in action…