Hi Doug,
I read through the latest SSA draft (version 0.97, Oct.12) and list my comments below.
Abstract:
typo - family
I think it's not necessary to state how a dataset was created in the SSA paper. The SSA should not get into the details about how a datacenter may choose to serve the datasets. It's up to the datacenters to do that and I guess there will be as many different ways as there are datacenters.
Same holds for 1.1 where the paper explicitly says that dynamically created datasets are the way a service will respond. I don't think this is true. It should be left to the discretion of the service provider to decide if he wants to deliver dynamically created or static or some mixture of files.
2.1, 3.3.2.5 are other examples where this comes up.
1.4:
What is the difference between MUST and REQUIRED. It is not explained anywhere.
1.4.1:
Why do you want to single one type of response format out? Why not have them all equal?
typo - encoded
Isn't there a gap between query compliant and fully compliant? What is a service did not implemnt all the "should" elements, but still answers with SSA-compliant data?
2.3:
How can you have metadata on virtual data? How should we anticipate all possible ways a user may ask for spectral cutouts, extraction etc. to be prepared to answer?
2.4.2:
spectral extraction - you may want to mention grism here as well.
3.3.2.3:
I thought that BAND is always a string. How can you have then "If a bandpass is spcedified as a string it is..."
3.3:
REQ is the abbreviation for recommended and then in the table, you use REC. This is inconsistent.
Apertures need not be circular, so you may want to phrase the respective sentence different.
3.3.3.6:
What does a photometric redshift mean in the context of spectra? What is it you want to allow the user to do? You confuse them by talking about blueshifts and local neighborhood if what you mean is a galactic photometric redshift.
3.3.6:
"Hence when data model attributes are indicated as mandatory of recommended in this document, this overrides any similar requirements specified in the Spectrum data model document."
I think these are two different things. The spectrum data model tells how to return the data. The SSA talks about how to contruct the answer to a request. I think it will happen that the data is returned in whatever units are appropriate for wavelength and the VOTable answer to the service is in meters. They are independent.
Do you think exposure time should be given in days? I would think that second is the fundamental unit to use. And if you think this makes observing dates look bad, why not allow both, days and seconds.
3.3.11:
I think that we have to solve the problem with spectral resolution. Some datasets will have the spectral resolution vay substantially over the spectrum. Thus a mean value or value at mean wavelength might be useless if the user is interested in the blue or the red part of the spectrum. Wouldn't it be easier to have two options for resolution reflecting the two fundamentally different ways instruments operate (either constant delta lambda or constant lambda/delta lambda)?
The service can then still choose how to answer by using a conversion (reference wavelength, etc.), but at least it's clear that the metadata is as accurate as we can get it.
Best wishes,
Inga
Received on 2006-11-20Z20:15:44