Aladin, VO standards, spectra and datacubes

Aladin, VO standards, spectra and datacubes

T.Boch, F.Bonnarel, P.Fernique

(CDS, Aladin development group)

SIA and SSA in Aladin• SIA is not dealing with spectra but with 2D images or

cubes.• Major breakthrough to access all registered services ( MAST, SDSS, CADC, VO_Paris MAMA…)• Different of older Aladin or Skyview or SUPERCOSMOS

accesses• In Aladin it’s possible to

– retrieve an SSA query response around a position, – visualize where it is on the screen …– load the spectrum into VOSPEC (or SPLAT or SPECVIEW)

using PLASTIC protocol (or ad hoc protocols)

IFU, Euro3D data• An IFU is a set of spatially evenly distributed spectra.• Euro3D is a FITS format for such IFU data where each

spectrum is a strongly standardized raw… (all the data points are in a cell) ASPID-SR, Giraffe are on line databases of such IFU – (ASPID-SR uses characterization internally, collaboration with

IgorChilingarian, Ivan Zolothukin and Mireille Louys)

• VO-Paris EuroVO 3D can send the positions of the spectra to Aladin and selected spectra to VOSPEC (using Plastic) see demo tommorrow by Igor.

• Interaction with EURO 3D tool using PLASTIC ?

Data Cubes• Evenly sampled data in 3 directions : extended WCS.

• Most common: x,y,lambda. Result of extended processing: – Radio Interferometry (NRAO, IRAM,JB, Westerbork…), – Fabry Perot (CIGALE, Scorpio,etc …,) in optical, – Processed IFU (Symphony, …)

• Aladin can load cubes, display them in blinking mode , extract some slice, show lambda profile.

• For VO access:– standard SIA is fine to query/retrieve small cubes,– for large ones we need an extended facility: several access

modes to the same dataset…

Multi access and views of a dataset

(preliminary generic dataset discovery )• Add several records in a DAL Extension RESOURCE

hooked to each observation description in the main query response RESOURCE:

• full download, preview, slice , « sub-cube », 1D spectrum at a given position.

• CGPS Archive navigator (collaboration with D.Durand/CADC) illustrates the Generic Dataset discovery concept of DAL (for complex data « tree of DAL protocols « 

Standards used

• Official standards: SIA, SSA, VOTABLE

• Emerging protocols:– DAL Extensions, – Characterization DM, – VO application communication (PLASTIC?)