Dear All,
I just read the dataService metadata document Anita circulated earlier today, and I have a counter proposal, far from being complete, but trying to visualise a hierarchical approach whereby the registry would try to answer a query not in a single step, but by scanning the repository at different level of complexity and details. Also, I tried to homogenise the naming convention onto different axes.
I just hope to generate ideas ... (will somebody read it ? Come on, it is not too long!)
Suppose the question is:
which space observatory instrument could provide calibrated
images in both B and V bands with a field of view of at least 2 arcmin,
and a resolution better than 0.2 arcsec ?
I will take the HST/WFPC2 as an example (am I biased ? maybe... )
The process obviously starts with the zero-order which basically contains the curator information listed in Bob's not-Bob's (BnB's) document.
Only the services surviving the constraint put at that level will be processed at further levels, and so on and so forth ...
The other levels could go like this:
First Level: (also partly from BnB's document)
Coverage.Spatial (BOX or Polygon) Coverage.Spectral (RADIO - GAMMA) Coverage.Temporal (Time ranges)
HST example:
HSTECF.Summary.Coverage.Spatial: (J2000,0,360,-90,90), sparse (how do I tell?) HSTECF.Summary.Coverage.Spectral: UV, OPTICAL, INFRARED HSTECF.Summary.Coverage.Temporal: 1990- HSTECF.Summary.DataType: image,spectrum
Notice that different HST archives might offer different or more datatypes (eg catalogs)
Second Level:
Coverage.Spatial.Resolution (range: min - max of all possible resolutions ) Coverage.Spatial.Window (range: min-max of all the Field of Views)
Coverage.Spectral.Resolution (range: min-max of all possible spectral resolution
s)
Coverage.Spectral.Window (range: min-max of all possible wavelengths )
Coverage.Temporal.Resolution (range: min-max of all possible sampling rates) Coverage.Temporal.Window (range: min-max of all possible epochs)
DataType.QualityType (image/raw, image/calibrated, image/combined,
spectrum-2D/raw, spectrum-2D/calibrated,
spectrum-1D/raw, spectrum-1D/calibrated,
catalog/astrometric, catalog/photometric, catalog/calibrated
Subresources: list of subresources
HST example:
HST.Summary.Coverage.Spatial.Resolution: 0.014-0.2 arcsec
HST.Summary.Coverage.Spatial.Window: 0.014 - 340 arcsec
HST.Summary.Coverage.Spectral.Resolution: ??? - ??? min-max sp.resol.across instr.
HST.Summary.Coverage.Spectral.Window: 90-1200 nm (???)
HST.Summary.Coverage.Temporal.Resolution: 0-1day (useful for HST ???)
HST.Summary.Coverage.Temporal.Window: 1990-
HST.Summary.DataType.QualityType: image/raw, image/calibrated, image/combined,
spectrum/raw/2D, spectrum/calibrated/2D,
spectrum/calibrated/1D
SubResources WFPC2, STIS, NICMOS, ACS, FOS, GHRS, FOC, WFPC, HSP, FGS
Again, not all the HST data centres offer the same kind of QualityTypes or Subresources. All this is Curator-specialised.
Third Level:
This level is no longer a Summary level for the resource itself At this point we need to specialise per SubResource. In the case of HST this means that here we start describing Instruments and their characteristics
Instrument.Name (eg, WFPC2) WFPC2.Coverage.Spatial a HTM is probably needed for a very sparse resource WFPC2.Coverage.Spatial.Resolution (0.05 - 0.199) <- min-max wfpc2 pix.scales WFPC2.Coverage.Spatial.Window (40x40 - 318x318 sq.arcsec) WFPC2.Coverage.Spectral.Resolution (2.15 - 665.42 nm) WFPC2.Coverage.Spectral.Window (98.1 - 1011 nm) WFPC2.Coverage.Temporal.Resolution (0.11 - 192400 sec) min - max exptimes WFPC2.Coverage.Temporal.Window (1993.95 - )WFPC2.DataType: image/raw, image/calibrated, image/combined, image/polarimetry WFPC2.SubResources: Filter, Detector, FocalPlane
Fourth Level,
WFPC2.Filter.Name WFPC2.Filter.Lambda.Central WFPC2.Filter.Lambda.FWHM WFPC2.Filter.Lambda.Min WFPC2.Filter.Lambda.Max WFPC2.Filter.RedLeak (yes/no) WFPC2.Filter.TransmissionCurve WFPC2.Filter.ZeroPoint WFPC2.Detector.Name WFPC2.Detector.PixelSize(x,y)
This should be enough to easily answer that WFPC2 provides the necessary filter bands, resolution and field of view.
As said, this is not thoroughly thought through But I hope it generates waves ...
Alberto Received on 2003-04-30Z18:24:50