What does "pseudo-filter" mean? (In the context of the DP0.2 schema)

In the DP0.2 schema, the term “pseudo-filter” is used in the definition of three columns in the Object table:

  • detect_isDeblendedModelSource
  • detect_isDeblendedSource
  • detect_isPrimary

Their definitions all include the phrase “… is not detected in a pseudo-filter (see config.pseudoFilterList)”.

If we search pipelines.lsst.io for pseudoFilterList, there are five matches to task configurations, in which pseudoFilterList is defined as the “Names of filters which may have no associated detection” or “Names of filters which should never be primary”.

Could someone help to clarify what the pseudo-filters are?


Thanks Melissa for this question! After discussions with Rubin Data Management, it sounds like sources detected in a pseudoFilter are actually just sky sources (i.e. these are not real astronomical objects, but are photometric measurements made on blank sky, in random locations that do not overlap real sources.) Initially it sounds like the term pseudoFilter was then inherited from the configurable list of sources that are not real (including sky) that was called a pseudoFilterList (where filter refers in this case not to the bandpass, but to the type of object, e.g. sky object. The pseudoFilter description is thus to help users make sure they select real astronomical objects of interest. One can do that by making sure they select with detect_isPrimary=True, which would exclude these other datapoints that fall into the pseudoFilter category. Does this answer the question?

Yes, thank you!!