Request for Modification (RFM) for the UCD vocabulary towards UCDList v1.5

This page summarises the steps for Modifications and Updates proposed in the UCD List Maintenance recommendation. The UCDListMaintenancePage summarises the past and current RFMs.

The second (on going) iteration for the Request for modifications of UCD terms is summarized in the following content.

These terms are submitted for evaluation to the UCD science committee (see details in the Maintenance Specification document).

UCDList v1.5 Request For Modifications, from June 2021 to Oct 2021


Accepted RFMs


Pending RFMs

From UCDList 1.3 RFM: pos.rotation, pos.euleraAngle, pos.quaternion, ... pos.heliocentric, pos.heliographic, etc .. postponed for better understanding

From UCDList 1.4 RFM: stat.histogram (use case to be further detailed). See further discussion below.


Rejected RFMs

  • phys.rotMeasure (concept already existing as phys.polarization.rotMeasure)

Proposed RFMs

Proposals from VeroniqueDelouille (VEP-UCD-001)

  • Proposed term: stat.skew
  • Proposed description: Statistical skewness, third moment of normalised data distribution function
  • Prefix: P
  • Rationale: This term was proposed actually by Veronique Delouille after FITSKeyword evaluation for solar datasets. Would complete the stat properties within the UCD tree. Would be useful for other data as well.
  • Used-in: SDO/AIA FITS keywords
  • Discussion:The statistical moments (except for the mean value) don't have the same units as the observed quantity, and thus those are another quantity extracted from the data. We propose to set the prefix to P.


  • Proposed term: stat.kurtosis
  • Proposed description: Statistical kurtosis, fourth moment of normalised data distribution function
  • Prefix: P
  • Rationale: This term was proposed actually by Veronique Delouille after FITSKeyword evaluation for solar datasets. Would complete the stat properties within the UCD tree. Would be useful for other data as well.
  • Used-in: SDO/AIA FITS keywords
  • Discussion: Skewness is related to the asymetry of the distribution, and the kurtosis help to identify outliers.


  • Proposed term: stat.mad
  • Proposed description: Statistical median absolute deviation from median
  • Prefix: P
  • Rationale: This term was proposed actually by Veronique Delouille after FITS Keyword evaluation for solar datasets this is a robust quantity to measure the spread of values in a data set when the statistic is not normal. Would complete the stat properties within the UCD tree. Would be useful for other data as well.
  • Used-in: ?
  • Discussion: Similar to stat.stdev, but using median operators instead of the mean.

Proposals from BaptisteCecconi (VEP-UCD-002)

UCD-SCI Answer: REJECTED. This term already exist as phys.polarization.rotMeasure

Proposals from StephaneErard (VEP-UCD-003)

  • Proposed term: pos.moc
  • Proposed description: Multi-order coverage
  • Prefix: S
  • Rationale: This term is used to tag a parameter containing a MOC (of any type, e.g, temporal, spatial, both, or any future MOC types)
  • Used-in: EPNcore-2.0
  • Discussion:The closest term available is pos.contour, but it doesn't seem adequate for multi-order coverage.

Sci-UCD Discussion: Three cases:

  • a votable field is tagged with "pos.moc", in this case, the xtype attribute must be present to tell what is the encoding of the MOC
  • "pos.moc" is in the EpnCore "measurement_type", to advertise the content of the product. Could be used with "dataproduct_type", to tell which axes are in the MOC (e.g., 'im' for classical MOC, 'mo' for STMOC, 'ts' for TMOC...)
  • A VOTable field with URLs pointing to MOC products. The UCD would be "meta.ref.url;pos.moc"


  • Proposed term: pos.projection
  • Proposed description: Geometric projection
  • Prefix: S
  • Rationale: This term is used to tag a parameter containing the projection in use, or to identified parameters that have been projected onto a map (map projected products).
  • Used-in: EPNcore-2.0
  • Discussion: The current UCD List contains `pos.lambert` which is a specific projection type, which can't cover all the needs for geometric projection tagging.


Sci-UCD Discussion: during EPN-TAP RFC review, MarkTaylor proposed to have Q prefixes for both pos.moc and pos.projection.

Proposal from AdaNebot (VEP-UCD-004)

  • Proposed term: time.period.oscillation
  • Proposed description: Period of pulsation of a body (similar to solar pulsations or oscillations)
  • Prefix: Q
  • Rationale: This term is used to tag a parameter containing the projection in use, or to identified parameters that have been projected onto a map (map projected products).
  • Used-in: https://academic.oup.com/mnras/article/487/3/3523/5512602
  • Discussion: This term was proposed actually by Ada Nebot to consider oscillating phenomena on sky objects and cover possible time measurements used in these studies. This is a first term proposal for addition concerning oscillating stars, etc ...

Proposal from MarkusDemleitner & BaptisteCecconi (VEP-UCD-005, initially in UCDList 1.4 RFM)

  • Proposed term: stat.histogram
  • Proposed description: An array-like object with counts or ratios in bins
  • Prefix: P
  • Rationale:
  • Used-in:
  • Discussion: See VEP-UCD-005, and UCDList 1.4 RFM for the detailed discussion.

Sci-UCD Further Discussion: The same discussion as that of pos.moc applies for the use cases. Depending on how what is tagged, P or S flag should be used, and a specific dataproduct_type may also be needed to advertise a product in an ObsTAP or EPN-TAP table.

Topic revision: r4 - 2021-07-01 - BaptisteCecconi
 
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