Registry hierarchical metadata

[Alberto Micol]

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)
DataType  (image,catalog,spectrum,event list,radio map, etc)

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)
WFPC2.Detector.Dimension(x,y)
WFPC2.FocalPlane. etc etc etc


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
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