Details
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Type:
Story
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Status: Done
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Resolution: Done
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Fix Version/s: None
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Component/s: obs_lsst
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Labels:
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Story Points:1
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Epic Link:
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Sprint:DRP S21b
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Team:Data Release Production
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Urgent?:No
Description
There has been much recent attention drawn to a certain mode of bad astrometric fits in SFM in the context of DC2/imsim data processing (see DM-30466 for discussion and diagnosis). A potential "fix" was added on DM-30490 in the form of an optional step in SFM astrometric fitting to perform a rejection on delta mag (ref - src) outliers in the match catalog before sending it to the fitter. Fairly extensive testing has proven this to be a most desirable option in that it fixes (i.e. a good astrometric fit is now found) almost all of the bad fit cases (the pesky "hot mess" of DM-30466 is the only exception we have noted thus far) and it does-no-harm for the cases that were not affected and already had good fits (see DM-30812 for details of this validation). As such, this option should be turned on by default for LSSTCam-imSim processing. The config parameter to be added is:
config.astrometry.doMagnitudeOutlierRejection=True |
To test this, I ran one of our bad fit examples on master and having set up this ticket branch:
Master:
This branch:
So all looks good!