www.g-vo.org

The Virtual ObservatoryThe Virtual Observatoryin Germany and abroadin Germany and abroad

A status report with examples/demos from GAVO

and other national VOs

www.g-vo.org

OverviewOverview

• The Virtual Observatory– Motivation– Approach

• The IVOA– Standards– Examples, demos

private demos are always possible !

• GAVO– Project– Results– Outlook

• Theory in the VO: – The Millennium Simulation database

www.g-vo.org

Astronomical data sets are Astronomical data sets are large, and getting largerlarge, and getting larger

Simulations as well(courtesy Simon White)

(courtesy Alex Szalay)(courtesy Alex Szalay)

www.g-vo.org

Most data is (or could be) onlineMost data is (or could be) online

Google(http://www.google.com/Top/

Science/Astronomy/Data_Archives/)

MPE (http://www.mpe.mpg.de/AstR/ )

www.g-vo.org

OpportunitiesOpportunities

• So, the Internet is (or could be) the world’s best telescope:– It has data on every part of the sky– In every measured spectral band:

optical, x-ray, radio..– As deep as the best instruments (2

years ago).– It is up when you are up– It’s a smart telescope: links objects

and data to literature on them– It even contains truly virtual data

(courtesy Alex Szalay)(courtesy Alex Szalay)

www.g-vo.org

www.g-vo.org

ProblemsProblems

• Data formats not uniform• Interfaces not uniform• Data sets very large• Data set far away (makes them larger)• How to find data of interest?• Computers have difficulty

understanding web pages

www.g-vo.org

Promises (/hopes) of the VO.Promises (/hopes) of the VO.

• To make results of astronomical research, more readily available to the community– data and applications

• To facilitate their– communication, reuse, comparison,

combination , checking

www.g-vo.org

How ?How ?

Online availability of datasets and applications

• Standardisation of – publication and discovery mechanisms– description/meta-data (FITS++)– selection mechanisms– form(at)s of transmitted data– data access protocols

• Why standardisation?

www.g-vo.org

Babylonian confusionBabylonian confusion

SDSS

ROSAT

2MASS

FIRST GAIA

N x M

www.g-vo.org

Why standardisationWhy standardisation

www.g-vo.org

We need a common We need a common languagelanguage

ROSATFIRST GAIA

SDSS2MASS

N + M

www.g-vo.org

Standardise on:Standardise on:

• Discovery• Data description (“meta-data”) • Data formats• Protocols• (Web) Application Interfaces• Query language

www.g-vo.org

Why (standardised) Why (standardised) protocolsprotocols??

• VO service oriented.• Data sets too large to move :

– You can FTP 1 MB in 1 sec (optimistically)– You can FTP 1 GB in min (= 1 $/GB)– You can FTP 1 TB in 2 days and 1K$– You can FTP 1 PB in 3 years and 1M$(numbers from Alex Szalay)

– SFTP even slower

• Remote filtering required to reduce size data sets

• “Move analysis to data”: services• Allow programmatic access to services

www.g-vo.org

www.g-vo.org

VO’s esperantoVO’s esperanto

www.g-vo.org

WarningWarning

• VO can not (and does not aim to) be everything to everyone

• Users will have to be able to visit the underlying data in all gory detail: provenance

• Even then standardisation helps• Agreement is hard to come by (see FITS)• Problems are hard ! • VO is still partially a research project.

www.g-vo.org

The International Virtual The International Virtual Observatory Alliance (IVOA)Observatory Alliance (IVOA)

Facilitate the international coordination and collaboration necessary for the development and deployment of the tools, systems and organizational structures necessary to enable the international utilization of astronomical archives as an integrated and interoperating virtual observatory.

www.g-vo.org

Alliance of national VOsAlliance of national VOs

www.g-vo.org

Working and Interest GroupsWorking and Interest Groups

• WGs– Standards and Process: how the IVOA works– Resource registry: where to register and discover

resources– Data Modeling: how to describe data sets– Semantics: how to understand one another– VOTable: standard format for tabular data sets– Data Access Layer: very simple data access services– VO Query Language: more sophisticated data access– Grid and web services: programmatic accessibility– Applications: stand alone, and together– VOEvent: astronomical telegrams in XML

• IGs– Theory: virtual observations for virtual universes– Open GridForum Astro-RG: VObs and virtual organisations– Data Curation and Preservation: how not to loose your data

www.g-vo.org

Publication standard:Publication standard:Resource RegistryResource Registry

• Implementations:– Searchable Registry at STScI – NCSA Publishing Registry – ESAVO Full Registry

• Client tools:– VOExplorer (AstroGrid)– Splat, SpecView, Aladin

www.g-vo.org

Messaging standard: Messaging standard: VOTableVOTable

• http://www.ivoa.net/twiki/bin/view/IVOA/IvoaVOTable

• XML format for tabular data• Column definitions included with data• Binary streams and FITS included• Understood by many client tools (see applications

set)– TOPCAT– VOPlot– Aladin– Many others

www.g-vo.org

VOTable exampleVOTable example

www.g-vo.org

Data Access Protocols IData Access Protocols I

• Simple protocols for discovering and retrieving data sets

• Generally HTP-GET based:– Base url:

http://www.g-vo.org/ssa?action=doQuery&archiveid=ssa.service.cdfs

– Query parameters:POS=53.161,-27.832&SIZE=0.2&BAND=0/&TIME=,&FORMAT=ALL

• Returns (heavily) annotated list of spectra with access URL for retrieving them.

www.g-vo.org

Data Access Protocols IIData Access Protocols II

• Examples from GAVO, for more usage examples see tool demos– Simple cone search (source catalogues)

• ROSAT source catalogues and photon event lists)

– Simple Image Access• ROSAT pointed observations and All-Sky

Survey fields

– Simple Spectral Access• Chandra Deep Field South optical follow up

www.g-vo.org

Registry + DAL protocols:Registry + DAL protocols:InteroperabilityInteroperability

Standard services, once registered,

can be found by client tools …

www.g-vo.org

InteroperabilityInteroperability

….and executedtogether (too

many ROSAT results to show all here!)

www.g-vo.org

InteroperabilityInteroperability

… and shown together

www.g-vo.org

Applications, toolsApplications, tools

• VO aware tools:– Images: Aladin– Source lists and tables: TOPCAT, VOPlot– Spectra: Splat, SpecView, VOSpec– 3D: VisIVO

• Application interoperability: Plastic– Messaging standard– Tying TOPCAT to Aladin to Splat to …– Uses VOTable to send data from one app to

another – All on your desktop

www.g-vo.org

GAVOGAVO

www.g-vo.org

GAVO: VO in GermanyGAVO: VO in Germany

• BMBF funded• In 2nd phase of financing• Institutes/people

– AIP: M. Steinmetz (Co-I), I. Nickelt– ARI-ZAH: PI J. Wambsganss (PI),

M. Demleitner, U. Stampa– MPE: W. Voges (Co-I), J.Kim, G.Lemson– Uni Tϋbingen: T. Rauch– TUM-Informatik: B. Gufler

www.g-vo.org

GAVO tasksGAVO tasks

• Investigate archiving and IVOA compatible publication

• Investigate data mining techniques• Participate in -, and represent IVOA efforts• Special emphasis on theory in the VO• GAVO-expertise center and archive @ARI• Support for custom services• Info/help on all things VO for Germany

(Please come by !)

www.g-vo.org

GAVO services, GAVO services, standard and customstandard and custom

• SCS and SIAP for ROSAT results (J.Zuther)• Cross matcher tool (used by S. Komossa)• SSA for CDFS spectra (G. Szokoly)• Publication A. Finoguenov’s A3266 data.• SSA for TMAP synthetic spectra (T. Rauch,

Tubingen)• Various virtual telescopes (Planck@MPA, K.Dolag,

J. Blaizot)• RASS source classifier (Class-X team)• Cluster finder (P. Schuecker et al)

– Now in AstroGrid-D (A. Carlson)

www.g-vo.org

GAVO current and planned GAVO current and planned projectsprojects

• GAVO@ARI– Archive for small science results– Feedback on all things GAVO– Hopefully long term

• Collaborative tool– Automated upload and annotation of

data– Wrap with IVOA protocols– Pre-publication collaboration capabilities

• Simulation registry

www.g-vo.org

Theory in the VOTheory in the VO

www.g-vo.org

Observations in the VOObservations in the VO

• Most VO efforts concentrate on observational data sets– simple observables: photons detected at a certain

time from a certain area on the sky– long history of archiving– pre-existing standards (FITS)– valuable over long time (digitising 80 yr old

plates)

• Standards observationally biased– common sky: cone search, SIAP, region– common objects: XMatch– data models: characterisation of

sky/time/energy(/no polarisation yet)

www.g-vo.org

Theory in the VO: issuesTheory in the VO: issues

• Simulations not so simple– complex observables– no standardisation (not even HDF5)– archiving ad hoc, for local use

• Moore’s law makes useful lifetime relatively short: few years later can do better

• Current IVOA standards somewhat irrelevant– no common sky– no common objects– requires data models for content, physics, code

www.g-vo.org

The The MillenniumMillennium database database + web server+ web server

• Post-processing results only• SQLServer database• Web application

– portal: http://www.mpa-garching.mpg.de/millennium/

– public DB access: http://www.g-vo.org/Millennium– private access: http://www.g-vo.org/MyMillennium

• Access methods– browser with plotting capabilities through VOPlot

applet– wget + IDL or R– TOPCAT plugin

www.g-vo.org

Usage statisticsUsage statistics