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  1. Request For Comments
  2. RFC-535

Make flux error a required field in reference catalogs

    Details

    • Type: RFC
    • Status: Implemented
    • Resolution: Done
    • Component/s: DM
    • Labels:
      None

      Description

      We currently have the flux error fields in reference catalogs listed as "optional" fields. Making them required (and filled with NaN if not available in already existing refcats) would simplify code in meas_algorithms, and ensure that newly created refcats have more useful minimal defaults. All of our new sources for reference catalogs will provide flux errors, and fluxes by themselves are not meaningful without their errors.

      The reference catalog schema is defined in the docstring for LoadReferenceObjectsTask in meas_algorithms, where the flux and fluxErr fields are defined as:

      • *referenceFilterName*_flux: brightness in the specified reference catalog filter (Jy)
      • *referenceFilterName*_fluxErr (optional): brightness standard deviation (Jy);

      In addition, Russell Owen and Jim Bosch agreed in comments on RFC-271 that the camFlux fields could be removed from the schema, so I also propose to remove them as part of this change. The existing docstrings do not make it clear how they are different from the regular *_flux fields. We're not using any such fields in the existing refcats on lsst-dev. These fields are defined in LoadReferenceObjectsTask as:

      • camFlux: brightness in default camera filter (Jy); omitted if defaultFilter not specified
      • camFluxErr: brightness standard deviation for default camera filter;
        omitted if defaultFilter not specified or standard deviation not available that filter
      • *cameraFilterName*_camFlux: brightness in specified camera filter (Jy)
      • *cameraFilterName*_camFluxErr (optional): brightness standard deviation
        in specified camera filter (Jy); omitted if no data is available;
        possibly nan if data is available for some objects but not others

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            Hide
            tjenness Tim Jenness added a comment -

            John Parejko what do you want to do about this RFC?

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            tjenness Tim Jenness added a comment - John Parejko what do you want to do about this RFC?
            Hide
            Parejkoj John Parejko added a comment - - edited

            I've filed triggered tickets on removing camFlux and forcing fluxErr to be in the minimal schema, so that future reference catalogs explicitly have flux errors.

            As to how to manage old catalogs, that seems to be the remaining point of contention.

            Show
            Parejkoj John Parejko added a comment - - edited I've filed triggered tickets on removing camFlux and forcing fluxErr to be in the minimal schema, so that future reference catalogs explicitly have flux errors. As to how to manage old catalogs, that seems to be the remaining point of contention.
            Hide
            ktl Kian-Tat Lim added a comment -

            John Parejko can you make a concrete proposal for the old catalogs to move this forward?

            Show
            ktl Kian-Tat Lim added a comment - John Parejko can you make a concrete proposal for the old catalogs to move this forward?
            Hide
            ktl Kian-Tat Lim added a comment -

            John Parejko: ping...

            Show
            ktl Kian-Tat Lim added a comment - John Parejko : ping...
            Hide
            Parejkoj John Parejko added a comment -

            After discussion with John Swinbank, I'm going to take the two marked implementation tickets as given, and drop the portion of the RFC dealing with old refcats. Since all new refcats will have fluxErr (DM-16338 is Done), this hopefully won't be an issue in the future as we transition to better (e.g. Gaia) refcats.

            Show
            Parejkoj John Parejko added a comment - After discussion with John Swinbank , I'm going to take the two marked implementation tickets as given, and drop the portion of the RFC dealing with old refcats. Since all new refcats will have fluxErr ( DM-16338 is Done), this hopefully won't be an issue in the future as we transition to better (e.g. Gaia) refcats.

              People

              • Assignee:
                Parejkoj John Parejko
                Reporter:
                Parejkoj John Parejko
                Watchers:
                Chris Morrison, Jim Bosch, John Parejko, John Swinbank, Kian-Tat Lim, Russell Owen, Simon Krughoff, Tim Jenness
              • Votes:
                0 Vote for this issue
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                8 Start watching this issue

                Dates

                • Created:
                  Updated:
                  Resolved:
                  Planned End:

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