Hello!

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International Virtual Observatory Alliance

Ajit Kembhavi, IUCAA, Pune

The Astronomer Vermeer 1632-1675

Data Storage and Retrieval

The Library of Alexandria 3rd Century BC

Star Positions

Stars in the Milky Way

The Hertzsprung-Russell Diagram

The Data Avalanche

• An increasing number of telescopes and large area detectors are producing immense amounts of data through imaging and spectroscopic surveys.

• Terabytes of data are now available, and Petabytes will soon be available from frequent all sky imaging.

• Vast databases are also being produced through simulations.

Wavelength Coverage

• The data spans the electromagnetic spectrum from the radio to the gamma-ray region.

• Obtaining, analysing and interpreting the data in different wavebands involves highly specialised instruments and techniques.

• The astronomer needs new tools for using this wealth of data in multiwavelength studies.

Virtual Observatories

• Manage vast data resources and provide these on-line to astronomers and other users.

• Provide tools for data analysis, visualization and mining.

• Develop interoperability concepts to make different databases seamless.

• Empower astronomers by providing sophisticated query and computational tools, and computing grids for producing new science.

VO Schema

Interactions

The Alliance

Members of the IVOA

IVOA Technology Initiatives

The IVOA has identified six major technical initiatives to fulfill the scientific goal of the VO concept.

IVOA-LISTS

• REGISTRIES: These collect metadata about about data resources and information services into a queryable database. The registry is distributed. A variety of industry standards are being investigated.

• DATA MODELS: This initiative aims to define the common elements of astronomical data structures and to provide a framework to describe their relationships.

• UNIFORM CONTENT DESCRIPTORS: These will provide the common language for for metadata definitions for the VO.

• DATA ACCESS LAYER: This provides a standardized access mechanisms to distributed data objects. Initial prototypes are a Cone Search Protocol and a simple Image Access Protocol.

• VO QUERY LANGUAGE: This will provide a standard query language which will go beyond the limitations of SQL.

• VOTable: This is an XML mark-up standard or astronomical tables.

VOTable

• This is a new data exchange standard produced through efforts led by Francois Ochsenbien of CDS, Strasbourg and Roy Williams of Caltech.

• VOTable is in XML format. Physical quantities come with sophisticated semantic information.

VOTable

• The format enables computers to easily parse the information and communicate it to other computers.

• Federation and joining of information become possible and Grid computing is easier.

• VOTable parsers have been developed in Perl, Java and C++.

• Enhancements and extensions are being considered.

VOTable Data

The data part in a VOTable may be represented using one of three different formats:

– FITS : VOTable can be used either to encapsulate FITS files, or to re-encode the metadata.

– BINARY : Supported for efficiency and ease of programming, no FITS library is required, and the streaming paradigm is supported.

– TABLEDATA : Pure XML format for small tables.

Science Initiatives

• Many IVOA projects have active Science Working Groups consisting of astronomers from a broad cross-section of the community representing all wavelengths.

• The focus here is to develop a clear perception of the scientific requirements of a VO.

• Projects within the working groups will develop new capabilities for VO based analysis.

• This will enable the community to create new research programs and to publish their data and research in a more pervasive and scientifically useful manner.

NVO-People

Caltech, Fermilab, JHU, NASA/HEARC, Microsoft, NCSA/UIUC, NOAO, NRAO, Raytheon ITS, SDSC/UCSD, SAO/CXC, STScI, UPenn, UPitts/CMU, UWis, USC, USNO, USRA, CVO

Registry and DIS

Terapix

Jodrell Bank

AVO Prototype Demo

Astrogrid:

Astronomy Catalogue Extractor

AVO: Aladin+SED

VO-India:VOPlot

CVO Collaborations

• There are three major projects at the CVO involving collaborations with other VO.

• CVO is collaborating with the German Astrophysical VO to incorporate ROSAT X-ray data and catalogues into the CVO system.

• CVO is collaborating with the Australian VO.to incorporate 2Qz and 2DF galaxy spectra into the CVO database.

• CVO is an associate member of NVO and is have put in place some components of the NVO galaxy morphology demo.

Australian –VO Collaborations

• The distributed volume renderer (dvr) software, is a tool for rendering large volumetric data sets using the combined memory and processing resources of Beowulf like clusters.

• A collaboration between the Melbourne site of Aus-VO and AstroGrid aims to develop the existing dvr software into a grid-based volume rendering service.

• Users will be able to select FITS-format cubes from a number of "Data Centres",have the data transferred to a chosen rendering cluster, and then proceed to visualise the volume of data remotely (See Demo).

Virtual Observatory - India

IUCAA

Persistent Systems

VO-India Projects

• VOTable Parser in C++; Streaming data• Web based FITS browser• Visualizer for VIZIER• Statistical packages for VIZIER and beyond• GALics data bases• Data mirror sites• Scientific data mining• Applications beyond astronomy

The VOPLOT Collaboration

The VOPlot Collaboration

• The idea for VOPlot was developed through a discussion between VO-I and CDS.

• VOPlot was developed by PSPL and IUCAA and was integrated into Vizier with the help of CDS.

• It was then decided to integrate VOPlot with Aladin, an interface was agreed on, and the integration is now complete.

• The collaboration was carried through a few short visits, phone calls and E-mail.

• Main persons: Sonali Kale et al (PSPL), Pierre Fernique and Francois Ochsenbien. (CDS).