1. 25 Jan 20061 The Virtual Observatory: Core Capabilities and Support for Statistical Analyses in Astronomy T HE US N ATIONAL V IRTUAL O BSERVATORY Robert Hanisch US National Virtual Observatory Space Telescope Science Institute

2. 25 Jan 20062 Overview The objective of the Virtual Observatory is to enable new science by greatly enhancing access to data and computing resources. The VO is intended to make it easy to locate, retrieve, and analyze data from archives and catalogs worldwide. Motivation; who’s involved; technical challenges and approach; capabilities Statistics in the VO Future

3. 25 Jan 20063 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)

4. 25 Jan 20064 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

5. 25 Jan 20065 Threads of the the VO Fabric Multiwavelength astrophysics Archival Research Survey astronomy Temporal astronomy NGC3104 Moore’s LawDigital detectorsThe InternetData Standards

6. 25 Jan 20066 Who is the National Virtual Observatory? US NVO development project, funded by NSF Information Technology Program and managed by NSF Astronomy Division, is in final year of 5-year project Funding is $10M+ over the 5 years 17 organizations (astro, CS, IT) involved –JHU (PI Alex Szalay), STScI, Caltech (Astronomy, IPAC, CACR), HEASARC, SAO, NRAO, NOAO, NCSA, SDSC, FNAL, USNO, et al. Collaboration with Gemini, LSST, et al.

7. 25 Jan 20067 International collaboration NVO is co-founder of the International Virtual Observatory Alliance IVOA now has 16 member projects Adopted a standards process based on W3C Forum for discussion and sharing of experience http://ivoa.net

8. 25 Jan 20068 Interoperability VizieR: Contains more than 4000 astronomical catalogues consisting of one or several tables. Problem: as the catalogues come from many different sources, the original descriptions are very heterogeneous: “Give me all tables containing the V magnitude in the Johnson system.” 144 different names for Johnson V !

9. 25 Jan 20069 Interoperability challenges Metadata standards Data discovery Data requests Data delivery Units Database queries Distributed applications; web services Authentication and authorization

10. 25 Jan 200610 Registries NVO Resource Discovery Computational Services Virtual Data ConeSearch SIAP, SSAP VOTable FITS, GIF,… Catalogs, Archives, Collections, Models ADQL, OSQ NVO Data Access Layer Queries Responses Portals, User Interfaces, Tools HTTP, Web, & Grid Services Data Models, UCDs, Metadata Architecture

11. 25 Jan 200611 NVO Components Data discovery and location –Resource Registry: Organizations, archives, tables, databases, services –Footprint Services Data access –Simple tables and observation logs: Cone Search –Images: Simple Image Access Protocol (SIAP) –Spectra: Simple Spectrum Access Protocol (SSAP) VOTables and FITS used to exchange data throughout the VO –Databases: SkyNode, with Astronomical Data Query Language (ADQL) –Transient events: VOEvent protocol –Data models, Space-Time Coordinates (STC)

12. 25 Jan 200612 NVO Components Distributed data storage –VOStore, VOSpace –Authentication and authorization Distributed computing –Web services –Grid services –Scalability

13. 25 Jan 200613 NVO Applications Registry Interface DataScope Coverage Maps Open SkyQuery WESIX (SExtractor) WCS Fixer Spectrum Services VOEvent Net Montage mosaics Integration with legacy software systems

14. 25 Jan 200614 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.

15. 25 Jan 200615 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, find known interesting or peculiar Discover and explore data in the Virtual Observatory objects and survey datasets that cover the region. 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.

16. 25 Jan 200616 Open SkyQuery 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.

17. 25 Jan 200617 Spectrum Services Search, plot, and retrieve SDSS, 2dF, and other spectra The 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.

18. 25 Jan 200618 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.

19. 25 Jan 200619 Coverage Maps The NVO Sky Statistics Service generates source counts, coverage maps, and links to downloadable data for catalog holdings available through the NVO protocols, including IRSA, NED and CDS VizieR View catalog coverage maps and source inventories for a position or object of interest.

20. 25 Jan 200620 WCS Fixer Repair image coordinates in images with inaccurate or misaligned coordinate systems.

21. 25 Jan 200621 VOEvent Net Explore the multiwavelength sky in the vicinity of transient events.

22. 25 Jan 200622 Montage Mosaics Make mosaics from 2MASS, DPOSS, or SDSS images.

23. 25 Jan 200623 VO Tools VOTable display and analysis –VOPlot, TOPCAT, Mirage Image display and analysis –Aladin, OASIS –Other standard display tools for downloaded data Spectrum display and analysis –VOSpec, SpecView

24. 25 Jan 200624 Statistics and the VO…

25. 25 Jan 200625 From single objects… Observations of small, carefully selected samples (often with a priori prejudices) of objects in one or a few wavelength bands

26. 25 Jan 200626 …to large-scale statistical studies 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

27. 25 Jan 200627 VO-aware statistics tools: VOPlot

28. 25 Jan 200628 VO-aware statistics tools: VOPlot

29. 25 Jan 200629 VO-aware statistics tools: VOPlot

30. 25 Jan 200630 VO-aware statistics tools: TOPCAT

31. 25 Jan 200631 VO-aware statistics tools: TOPCAT

32. 25 Jan 200632 VO-aware statistics tools: TOPCAT

33. 25 Jan 200633 VO-aware statistics tools: TOPCAT

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36. 25 Jan 200636 Pairwise plots Box plots K-means

37. 25 Jan 200637 Statistics in the VO What more is needed? –Scalability: Extend analysis to 10^9 measurements or more –Operate on data where it resides –VOSpace Probabilistic cross-matching

38. 25 Jan 200638 Statistics in the VO Image stacking –White et al. (2006) detect radio counterparts to SDSS QSOs at level 30X below rms noise via median stacking of 41,000 FIRST images

39. 25 Jan 200639 Next steps NVO Facility –Joint NASA/NSF program, operations to begin in 2007 –Partnership between NASA data centers, major ground- based observatories, university research groups. Need to define the requirements for VO-enabled statistical analysis. VO concept is being adopted broadly –AGU special session on VOs –NASA solicitation for Virtual Observatories for Solar and Space Physics Data (VxOs); AISRP support for VO technology

40. 25 Jan 200640 http://us-vo.org/