Visualization of Complex Observational and Theoretical Datasets in the Virtual Observatory
aa r X i v : . [ a s t r o - ph ] N ov Astronomical Data Analysis Software and Systems XVII
P2.12
ASP Conference Series, Vol. XXX, 2008J. Lewis, R. Argyle, P. Bunclarck, D. Evans, and E. Gonzales-Solares, eds.
Visualization of Complex Observational and TheoreticalDatasets in the Virtual Observatory
Igor Chilingarian , Ivan Zolotukhin Abstract.
Our presentation is aimed at data centers providing access tocomplex observational and theoretical data and to the users of these resources.We show how to visualize complex datasets stored in the VO enabled dataarchives using existing VO client software and PLASTIC, a prototype of anapplication messaging protocol, for interaction between archive query resultsand tools. We demonstrate how to display and explore observable IFU datasets,provided within the ASPID-SR archive, using CDS Aladin, ESA VOSpec, andVO-Paris Euro3D Client. In the second part of the paper we show how touse TOPCAT for displaying results of N-body simulations of galaxy mergersavailable in the HORIZON GalMer database.
1. Introduction
At present the International Virtual Observatory has become a rapidly growinginitiative. Recently, several VO resources providing access to complex observa-tional and theoretical datasets have appeared. Providing the transparent andefficient data access and visualization mechanisms are the crucial points for datasources to be used by the scientific community.In this paper we demonstrate how to visualize complex observable and the-oretical datasets stored in the VO-enabled data archives using a WEB-browser,existing VO client software and PLASTIC (PLatform for Astronomical ToolsInter-Connection), a prototype of an application messaging protocol, for inter-action between archive query results and tools. The technical details of themiddle layer software implementation are given in a paper “Middleware for datavisualization in VO-enabled data archives” by Zolotukhin & Chilingarian (thisvolume).
2. ASPID-SR Archive
ASPID-SR (Chilingarian et al. 2007a) is a prototype of an archive of heteroge-neous science ready data, containing observations obtained at the Russian 6-m Observatoire de Paris-Meudon, VO-Paris Data Centre; LERMA, UMR 8112, 61 Av. del’Observatoire, Paris, 75014, France Sternberg Astronomical Institute, Moscow State University, 13 Universitetsky prospect,Moscow, 119992, Russia Chilingarian & Zolotukhin
Figure 1. Interaction between the ASPID-SR web-interface, CDS Aladin,ESA VOSpec, and VO-Paris Euro3D Client. telescope. This resource provides the world largest collection of science-ready 3Dspectroscopic data, including about a hundred integral-field unit (IFU) datasetsmostly for extragalactic objects and scanning Fabry-Perot interferometric ob-servations (about 70 data-cubes for nearby galaxies in H α and [OIII] emissionlines).ASPID-SR provides implementation for several existing IVOA standards:Characterisation Data Model (Louys et al. 2007, one of the reference implemen-tations), Spectrum Data Model (McDowell et al. 2007) Simple Spectral AccessProtocol (Tody et al. 2007).Interaction between VO client applications and the ASPID-SR archive in-terface is implemented in several stages:1. Querying the XML characterisation metadata (Zolotukhin et al. 2007)using the web interface.2. Light-weight Java applet is integrated into the HTML pages, containingthe query response; it detects a PLASTIC hub, connects to it, and checkswhether other tools (Aladin, VOSpec, VO Paris Euro3D Client) are regis-tered within it. If the applications are not detected, they are started usingJavaScript and Java WebStart.3. As soon as all the used applications have been started and registered withinthe PLASTIC hub, a small script is sent to CDS Aladin to display the DSS2image of the area, corresponding to the position of the IFU field of view.At the same time, the IFU dataset in the Euro3D FITS format (Kissler- isualization of Complex Datasets in the VO Figure 2. This figure demonstrates interaction between the Horizon GalMerDatabase, containing the results of N-body simulations, and TOPCAT usedfor visualization. Two snapshots of a merger of giant Sa and Sc galaxies areshown.
Patig et al. 2004) is loaded into VO Paris Euro3D Client (Chilingarian etal. 2007b).4. Positions of IFU fibers are sent from VO Paris Euro3D Client to CDSAladin and overplotted on the DSS2 image.5. User can interactively select either groups of fibers or individual ones usingCDS Aladin. An extracted spectrum (or co-added spectra of several fibers)is sent to ESA VOSpec using PLASTIC by clicking on the correspondingbutton in the user interface of VO Paris Euro3D Client.This implementation follows the principles of handling 3D spectral datasets,proposed and described in Chilingarian et al. (2006)
3. The Horizon GalMer Database
The Horizon GalMer database (Di Matteo et al. 2007a) contains results of N-body simulations of mergers of galaxies (Di Matteo et al. 2007b) of differentmorphological types. To model the galaxy evolution, the Tree-SPH code is used,where gravitational forces are calculated using a hierarchical tree method andgas evolution is followed by means of smoothed particle hydrodynamics. Thefirst release of the data contains about 900 simulations (with limited inclinationangles of the orbits), in 50 to 70 snapshots each, representing mergers of giantgalaxies of different morphological types (E0 to Sd).The web-based access to the simulation results is provided. The middle-ware described in Zolotukhin & Chilingarian (this conference) is used to providePLASTIC based communication between archive web-pages and TOPCAT usedas a tool for displaying the 3-dimensional snapshot datasets, as well as starformation histories of the merging galaxies.
Chilingarian & Zolotukhin
The Horizon GalMer database implements a prototype of IVOA SimpleNumeric Access Protocol Data Model (Lemson et al., in prep.) serialized as therelational database schema.
4. Summary
The two implementations described above demonstrate that the observable andtheoretical datasets having complex structure can be discovered and accessedat the present stage of the Virtual Observatory development, when not all theinteroperability standards are yet established. A WEB-browser and existingclient applications interacting via simple application messaging protocol such asPLASTIC provide an infrastructure powerful enough for scientific usage of thedata sources in a VO framework.
Acknowledgments.
Authors wish to thank ADASS organizing committeefor the financial support provided. Travel of IZ is also supported via RFBRgrant 07-02-08846.