Presentation is loading. Please wait.

Presentation is loading. Please wait.

VO-DAS Chenzhou CUI Chao LIU, Haijun TIAN, Yang YANG, etc National Astronomical Observatories, CAS.

Similar presentations


Presentation on theme: "VO-DAS Chenzhou CUI Chao LIU, Haijun TIAN, Yang YANG, etc National Astronomical Observatories, CAS."— Presentation transcript:

1 VO-DAS Chenzhou CUI Chao LIU, Haijun TIAN, Yang YANG, etc National Astronomical Observatories, CAS

2 VO Data Access Service (VO-DAS)  An OGSA-DAI based service system to provide unified access to astronomy data, including catalogs, images and spectra.  Goals of VO-DAS  Supporting high volume data query  Interlinking distributed and heterogeneous archives catalogs, images, spectrums works for astronomers  Providing a software that works for astronomers

3 First Science Paper from China-VO  Candidate Milky Way satellites in the Galactic halo ( Liu et al., 2008, A&A)  SDSS DR5 photometric data were searched for new Milky Way companions or substructures in the Galactic halo.  Data analysis procedures were based on the VO-DAS.  Five candidates are identified as over-dense faint stellar sources that have color-magnitude diagrams similar to those of known globular clusters, or dwarf spherical galaxies.

4 Predicted Features  Goals: Uniform access to heterogeneous distributed datasets, bulk of data support  Functions  Catalog, image, and spectrum support  Dataset encapsulating and registry  Data discovery  Metadata description  Jointed query on heterogeneous databases  Bulk of data transfer support  Sync and async queries  Query status tracer  ADQL support

5 Architecture  Components  VO-DAS server  DataNode  Clients  Registry  Data storage

6 Technical Highlights  OGSA-DAI based data node  Asynchronous query and cross match on distributed databases  Extended ADQL, supporting catalog, image and spectrum at the same time

7 Async Query  Query segmented into sub- queries  Queries assigned to specific DataNodes  Query results transfer among DataNodes  Final results sent to data storage service (VOSpace, FTP, etc)  VO-DAS server supervises the whole process  No data exchange between DataNode and VO-DAS server

8 Extended ADQL  SELECT s.ra, s.dec, s.g-s.i gi, s.i FROM SDSSDR5:star s WHERE s.ra>=120 AND s.ra =25 AND s.dec =19 AND s.i =0 AND s.g- s.i<=1  SELECT f.Access_reference FROM SDSSDR6:specfile f, SDSSDR6:sspParams s WHERE s.specID=f.specID AND f.SNR>10 AND s.alphafea -0.9

9 VO-DAS Clients  GUI  CLI  WebBrowser  MATLAB Client

10 Interoperability PLASTIC, SAMP

11 MATLAB based DM environments VO-DAS MATLAB VO-DAS Client MATLAB Database Toolbox Local DB Java Libraries VOTables PLASTIC VO Tools (Aladin, TOPCAT) Astrobox

12 AstroBox  A plug-in package for MATLAB to provide an astronomical data mining application service, supporting VO protocols and tools.  A high-level data analysis environment supporting:  PLASTIC  VOTable  Local DB  VO-DAS client  Astronomical algorithms VO-DAS MATLAB VO-DAS Client MATLAB Database Toolbox Local DB Java Libraries VOTables PLASTIC VO Tools (Aladin, TOPCAT) AstroBox

13 MATLAB based DM environments (cont.)

14 Science case : Sub-structure study for the Galaxy

15 Methodology  Density count in area (ra=120~270deg, dec=25~70deg) where i=19~22 and g-i=0~1 in the SDSS DR5 (bin=0.2x0.2deg)  Obtained 524 over density area  Calculate CMD for each area  Identify these CMDs by hands

16 Results

17 Work done by VO-DAS  70 millions records queried from SDSS DR7 database  Calculate CMD for each over density area Other tasks done by MATLAB

18 Lessons learned  Grid and SOAP based data access solution is feasible  Too complex to control  Low performance

19 Current: RESTful TAP DAS

20 Collaboration Environment  CSCW (computer supported cooperative work)  e-Science  VO

21


Download ppt "VO-DAS Chenzhou CUI Chao LIU, Haijun TIAN, Yang YANG, etc National Astronomical Observatories, CAS."

Similar presentations


Ads by Google