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NVO Science Applications

THE US NATIONAL VIRTUAL OBSERVATORY

Robert HanischUS NVO Project Manager

Space Telescope Science Institute

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Astronomy is facing a data avalanche

Multi-Terabyte (soon: multi-Petabyte) sky surveys and archives over a broad range of wavelengths

Billions of sources, hundreds of attributes per source

1 nanoSky (HDF-S)

1 microSky (DPOSS)

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The changing face of observational astronomy

• Large digital sky surveys are becoming dominant source of data in astronomy: > 100 TB, growing rapidly– SDSS, 2MASS, DPOSS, GSC, FIRST, NVSS, RASS, IRAS,

QUEST, GALEX, SST; CMBR experiments; Microlensing experiments; NEAT, LONEOS, and other searches for Solar system objects

– Digital libraries: ADS, astro-ph, NED, CDS, NSSDC– Observatory archives: HST, CXO, space and ground-based– Future: PanSTARRS, LSST, and other synoptic surveys;

astrometric missions, GW detectors

• Data sets orders of magnitude larger, more complex, more homogeneous than in the past

• Roughly 1 TB/Sky/band/epoch– Human Genome is < 1 GB, Library of Congress ~ 20 TB

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Toward a “new astronomy”

• Past: Observations of small, carefully selected samples (often with a priori prejudices) of objects in one or a few wavelength bands

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Toward a “new astronomy”

• Future: Multi-wavelength data for millions of objects, allowing us to:– Discover significant patterns from the analysis of

statistically rich and unbiased image/catalog databases

– Understand complex astrophysical systems via confrontation between data and sophisticated numerical simulation

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Toward a “new astronomy”

• Discovering new phenomena and patterns in these datasets will require simultaneous access to multi-wavelength archives, advanced visualization and statistical analysis tools

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The Virtual Observatory is…

• A set of international standards to share complex data• A modular set of tools to work with distributed data• A simple environment to publish data to• An essential part of the research astronomer’s toolkit• A catalyst for world-wide access to astronomical

archives• A vehicle for education and public outreach

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The Virtual Observatory is not…

• A replacement for building new telescopes and instruments

• A centralized repository for data• A data quality enforcement organization

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Science prototypes

• Science demonstrations show capabilities of new infrastructure, motivate and guide technical developments. For example:– Data discovery, multi-λ comparisons– Search for brown dwarfs– Galaxy morphologies in clusters– Globular cluster simulations

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Science results

• Padovani et al. (2004)) demonstrates that VO tools are mature enough to produce cutting-edge science results by exploiting astronomical data beyond classical identification limits (R 25)

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Science results

• McGlynn et al. (2004) classified all unidentified ROSAT WGACAT objects using VO data access methods to cross-correlate multi-wavelength catalogs– Technique applied to

find candidate X-ray binaries and now to SDSS photometric catalog

• More than 400 papers related to “virtual observatory” in ADS

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Science results

• AAS Special Session papers– de Mello, D.; Sosey, M. “Environments of Starburst

Galaxies Diagnosed with the NVO”– Van Duyne, J.; Lucas, R.; Tamura, T.; Rohde, D.

“Searching for Distant Galaxy Clusters: Utilizing the Virtual Observatory for Multiwavelength Images and Survey Cross-correlation”

– Miller, C. J.; Krughoff, K. S.; Ho, T. K. “A Dust Extinction Web Service in the VO Framework”

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NVO Registry Portal

Find source catalogs, image archives, and other astronomical resources registered with the NVO

A Registry is a distributed database of Virtual Observatory resources: primarily access services for catalog, image, and spectral data, but also descriptions of organizations and data collections. There are several coordinated registry implementations that share information by harvesting each other's resources. This registry is at STScI in Baltimore, MD.Searches for resources can be done by keyword, or advanced queries can be expressed in the SQL language. The registry is open for humans through web forms, or machines through SOAP web services.

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DataScope

Using the NVO DataScope scientists can discover and explore hundreds of data resources available in the Virtual Observatory. DataScope uses the VO registry and VO access protocols to link to archives and catalogs around the world. Users can immediately discover what is known about a given region of the sky: they can view survey images from the radio through the X-ray, explore archived observations from multiple archives, find recent articles describing analysis of data in the region,

Discover and explore data in the Virtual Observatory

A summary page provides a quick précis of all of the available data. Users can download images and tables for further analysis on their local machines, or they can go directly to a growing set of VO enabled analysis tools, including Aladin, OASIS, VOPlot and VOStat.

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OpenSkyQuery

Cross-match your data with numerous catalogs

OpenSkyQuery allows you to cross-match astronomical catalogs and select subsets of catalogs with a general and powerful query language. You can also import a personal catalog of objects and cross-match it against selected databases.

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Spectrum Services

Search, plot, and retrieve SDSS, 2dF, and other spectraThe Spectrum Services web site is dedicated to spectrum related VO services. On this site you will find tools and tutorials on how to access close to 500,000 spectra from the Sloan Digital Sky Survey (SDSS DR1) and the 2 degree Field redshift survey (2dFGRS). The services are open to everyone to publish their own spectra in the same framework. Reading the tutorials on XML Web Services, you can learn how to integrate the 45 GB spectrum and passband database with your programs with few lines of code.

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Web Enabled Source Identification with Cross-Matching (WESIX)

Upload images to SExtractor and cross-correlate the objects found with selected survey catalogs.

This NVO service does source extraction and cross-matching for any astrometric FITS image. The user uploads a FITS image, and the remote service runs the SExtractor software for source extraction. The resulting catalog can be cross-matched with any of several major surveys, and the results returned as a VOTable. The web page also allows use of Aladin or VOPlot to visualize results.

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How to Publish to the NVO

Make your data collection available to others

"how-to" document is aimed anyone who has data and would like to share it with the astronomy community through the NVO. Remember, though, data is not the only thing you can publish—you can also publish services. That is, if you have a piece of software that might be useful to others and would like to make it accessible over the network, publishing it as a service makes it possible for other NVO applications to make use of it.

The NVO is a powerful environment for locating and integrating a wide variety of data originating from many different instruments and exploring many different research questions in astronomy. But how does data get into that environment in the first place? Data is exposed to the NVO environment through a process called publishing. This

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Future VO-enabled applications

• NVO applications for 2005-2006 TBD in consultation with Science Steering Committee– Fast data inventory service– Sky coverage footprint services– WCS fixer– Integration of DataScope with VOEvent notifications– Forms-based interfaces for database queries and

cross-correlations

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Frequently used tools

• Aladin (CDS, Strasbourg); http://aladin.u-strasbg.fr/aladin.gml

• VOPlot (VO India); http://vo.iucaa.ernet.in/~voi/voplot.htm

• Mirage (Lucent); http://cm.bell-labs.com/who/tkh/mirage/index.html

• TOPCAT (Starlink); http://www.star.bris.ac.uk/~mbt/topcat/

• Specview (STScI); http://www.stsci.edu/resources/software_hardware/specview

• VOSpec (ESAC); http://esavo.esa.int/vospec/