UCD review

[mcdittmar]

This issue is spawned from PR #4, which has some discussion about the new UCDs and verifying those in the current document.

Action List Candidates:

1. Review/Confirm the UCDs selected for the new model elements.
2. Update UCD Vocabulary reference in Section 3.4. The file currently being referenced is NOT a REC/EN, but appears to be very close to V1.3 of the UCD vocabulary.
3. Per this comment, add tags to the document which enables validation of the UCDs contained in the document.
4. Per this wiki page, the UCD mentioned has been updated in V1.1, but the VOTable example did not follow suite. Correct this and add closure statement to the wiki page.

Item 1: The following shows the UCDs put into this PR, and the suggested values per the UCD Builder utility.

• Data.SpectralAxis.order => "instr.order"
• Data.SpectralAxis.relorder => "instr.order"
  • UCD builder suggests: "stat.variance;instr.order" for both, though "instr.order" can stand on its own.
• Data.FluxAxis.Accuracy.LowerLimit => "stat.error.phot.flux.density;em.*;stat.min" (Same as StatErrorLow)
  • UCD builder suggests:
    • "statistical lower limit" -> "stat.value;stat.min"
    • "detection lower limit" -> "instr.saturation;stat.min"
• Data.FluxAxis.Accuracy.UpperLimit => "stat.error.phot.flux.density;em.*;stat.max" (Same as StatErrorHigh)
  • UCD builder suggests:
    • "statistical upper limit" -> "stat.value;stat.max"
    • "detection upper limit" -> "instr.saturation;stat.max"

[mcdittmar]

Item 1: Follow-up,

• pointer to discussion from DM mail list.
• one should read the discussion for context, but in summary: there are several alternate suggestions
  • Data.FluxAxis.Accuracy.LowerLimit
    • stat.error;phot.flux;stat.min
    • instr.sensitivity;phot.flux;stat.min
    • instr.saturation;phot.flux
  • Data.FluxAxis.Accuracy.UpperLimit
    • stat.error;phot.flux;stat.max
    • instr.sensitivity;phot.flux;stat.max
    • instr.sensitivity;phot.flux

[lmichel]

Upper/lower limits are not errors and it is important that UCDs contain min/max words. This makes me voting for instr.sensitivity;phot.flux;stat.min and instr.sensitivity;phot.flux;stat.max

I've however a doubt about whether stat.max fits with upper or lower limit. The upper limit is something saying that if there is a source here, its flux is below the upper limit.
In that sense the upper limit is rather the lowest flux that can be detected, then it should be instr.sensitivity;phot.flux;stat.min

[mcdittmar]

Given the various inputs from the discussion it seems to me like these are the most appropriate options:

• lower limit: "instr.saturation;phot.flux.density;stat.min" = minimum flux of the source due to instrument saturation
• upper limit: "instr.sensitivity;phot.flux.density;stat.max" = maximum flux of the source to remain undetected due to instrument sensitivity

Note: I went with 'phot.flux.density' merely because that is what is extensively used for the flux values.

[mcdittmar]

I think this issue should JUST involve the new element UCDs.. actions 2-4 should be handled by Issue #7.