ranges

[Robert Hanisch]

Having finally caught up on my e-mail, there is in my mind one major issue I
would like some additional discussion on prior to the interop workshop.
Elizabeth's AstroGrid prototype registry, Anita's document on frequency
coverage, and Bob Jackson's previous work on telescope and instrument
capabilities, all use range specifications for quantities such as bandpass
coverage.  The RSM V.6 document generally does not do this.  In fact, I have
a bit reluctant to put in specific metadata elements for upper and lower
limits, as they are often poorly defined (what are the exact wavelength
limits for various optical filters?), I am not sure they will be terribly
helpful in locating data of interest, and they increase the burden on the
data provider in registering their resources.  For example, I know that HST
observations can be described as (near) IR, optical, and UV, but it would be
non-trivial to say exactly what the lower and upper wavelength limits would
be.  Moreover, if I were to select particular limits, say at lambda max of
9000 angstroms, and someone submits a query to the registry looking for data
at 9005 angstroms, would we want to steer them away from HST?  I don't think
so.

Of course, one could collect metadata for the registry with the range
information, and then filter queries so that requests are interpreted with
fuzzy boundaries.  In other words, one can also convolve the metadata with a
blurring function, if you will (my image restoration background is now
showing), but deconvolution is an inverse problem and much harder.

This all argues in favor of Elizabeth's, Anita's, and Bob J's approaches.  I
am just not yet convinced that we will really use metadata in the registry
at this level of detail, and thus am not yet convinced that we should make
resource and service providers provide it, especially when it is ambiguous
to start.

Eager to hear people's comments.  I would like to come to Cambridge with V7
of the RSM document that reflects the majority opinion.

Bob