1. Federated Discovery and Access in Astronomy Robert Hanisch (NIST), Ray Plante (NCSA)

2. 2 Data in astronomy 1-d, 2-d, 3-d: intensity/polarization vs. energy, time, position, velocity tables: catalogs, x-ray event lists, radio visibility measurements various data processing levels, from raw to “science-ready” 2

3. 3 Quantity and distribution  ~70 major data centers and observatories with substantial on-line data holdings  ~10,000 data “resources” (catalogs, surveys, archives)  Data centers host from a few to ~100 TB each, currently ~1+ PB total  Current growth rate ~0.5 PB/yr, expected to increase soon  Current request rate ~1 PB/yr 3

4. 4 The Virtual Observatory  The VO is a data discovery, access, and integration facility  International collaboration on metadata standards, data models, and protocols  Image, spectrum, time series data  Catalogs, databases  Transient event notices  Software and services  Distributed computing (authentication, authorization, process management)  Application inter-communication  International Virtual Observatory Alliance established in 2002, patterned on WorldWideWeb Consortium (W3C)  21 national and international participants 4

5. 5 VO architecture 5

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8. 8 Data discovery 8

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10. 10 Data discovery 10

11. 11 Data discovery 11

12. 12 Data discovery 12

13. 13 Data discovery 13

14. 14 Data discovery 14

15. 15 How does this work? Registry!  Used to discover and locate resources—data and services—that can be used in a VO application  Resource: anything that is describable and identifiable.  Besides data and services: organizations, projects, software, standards  Registry: a list of resource descriptions  Expressed as structured metadata in XML to enable automated processing and searching Metadata based on Dublin Core w/ astro-extensions 15

16. 16 Registry framework 16 Data Centers Local Publishing Registry Full Searchable Registry Local Publishing Registry Full Searchable Registry (pull) harvest replicate search queries Users, applications OAI/PMH