IVOA Interop meeting 05/17/2006 Victoria F.Bonnarel (CDS) Generic Data discovery, Cube acces: CGPS Archive browser F.Bonnarel,T.Boch,D.Durand (CDS, CADC)

IVOA Interop meeting 05/17/2006

Victoria F.Bonnarel (CDS)

Generic Data discovery, Cube acces: CGPS Archive browser

F.Bonnarel,T.Boch,D.Durand

(CDS, CADC)



Generic Dataset Discovery

• In the VO, there are complex data or data which require different acces modes or views.– Eg : Data Cubes, – Echelle spectra (?), – IFU data as a collection of Spectra, – Images with Previews and access to

associated catalog of sources, – etc…




• This was a strong motivation for some people in the VO to propose structuration in DAL protocols– AVO and CDS proposed and prototyped the IDHA interface still

used in the Aladin server– Several groups (ESAC, CDS, in 2004 IVOA notes ) proposed a

structuration of SIA Query response– ESAC and CDS posted an IVOA note on Extensions to SIA

query response in 2005

(complex data access has been a strong motivation for that, several presentations at IVOA interop meetings)




• Recently Doug Tody introduced the Generic DataSet Discovery concept taking into account this « one DataSet/Several Access and Views » requirement.– A Generic data set discovery is a DAL protocol (defining INPUT

PARAMETERS and Query Response) for all Kind of data (simple and complex)

– The query response includes curation metadata, characterization, and access reference to the Whole Dataset

– In addition: Description of Several acces (or views) for a given Dataset wil be done in a second Table, using standard simple acces DAL protocols interfaces, supposed to include Image Generation Parameters for all access modes.



Data Cubes in the VO(summary of recent DAL discussions)

• Assumption: Regurlaly sampled data cubes is an Image (full access relies on SIA, not on SSA)

• For large cubes there is a strong need for access to– global previews, – moment or segmentation maps, – 2 D slices excerpt, 1 D extracted spectra, 1D or 2D projections

on various directions, – Subcubes or resampled cubes of smaller size.

• Cubes are a Good testbed for Generic Dataset Discovery concept



CGPS Archive browser

• CGPS is a Radio Survey of the Galactic plane. It contains Radio continuum observations at several wavelengths and HI and CO lines 3D Radio Cubes

• The Archive is operated at CADC by D.Durand. It includes Access to the Radio observations and to Reprocessed Iras data for the FAR infrared.

• The CGPS Archive browser is an online service developped by CADC and CDS using Aladin and SIA + Extension query response description of the data.

• The prototype shown here adds an acces to 1D spectrum which is retrieved and visualized in SpecView.

•

















CGPS AB: How does it work?

• Main data set description: standard SIA query response description of the cube and Images.

• Full Retrieval as standard SIA access method

• Extension RESOURCE contains several access and views descriptions RECORDS for each dataset with ad hoc templated URLS



CGPS AB: How does it work?

• Interface uses this information – to customize the « 2D Slicer » and « 1D

spectrum position grabber » Windows, – to launch the appropriate request , – and to load the result in either Aladin,

theWebBrowser, or SpecView



Future plans

• Release this 1D spectrum facility in the online Browser (Specview or VOSPEC?)

• Other SIA + Extensions services implementations:– CFHTLS Archive Browser?

– Replace the current IDHA interface in Aladin • IVOA Dal protocols compatibility:

– When available, replace the SIA description by main Generic Dataset Discovery Query response

– Standardize the various access modes descriptions and Parameters according to IVOA DAL recommendations for SIA and SSA when available. See also our talk for a AccessAndViews DM (Friday morning)



Acknowledgments

• The Archive Browser (and SIA + Extensions prototypes) benefited from discussions with– P.Osuna , J.Salgado, (ESAC)– M.Louys, P.Fernique, (Strasbourg)– A.Richards, (AstroGrid)– A.Micol (ECF)– L.Simard, JJ Kavelaars, (CADC)– Doug Tody, (NVO)– etc …

Documents

IVOA Interop meeting 05/17/2006 Victoria F.Bonnarel (CDS) Generic Data discovery, Cube acces: CGPS Archive browser F.Bonnarel,T.Boch,D.Durand (CDS, CADC)