Details
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Type:
Story
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Status: To Do
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Resolution: Unresolved
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Fix Version/s: None
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Component/s: meas_algorithms
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Labels:
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Epic Link:
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Team:Data Release Production
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Urgent?:No
Description
Erin Sheldon reports (and Eli Rykoff concurs) that SourceDetectionTask behaves inconsistently when thresholdType=variance vs. thresholdType=stdev; the latter uses an empirical estimate of the variance from some image (I'm not sure whether it's the Gaussian-smoothed image or the original) while the former uses the variance plane of the other image.
We want SourceDetectionTask to yield 5-sigma point-source SNR detections on the original image regardless of the thresholdType, and need to fix whichever of these is incorrect (strongly suspected to be thresholdType=variance, but I need to re-do the detection algebra and look harder at the code to be sure). If we can't change the meaning of a thresholdType without lots of breakage, we should add a new one with the desired behavior and update the docs (and probably deprecate the confusing one).
Looking at the code, I am pretty sure they are both operating on the post convolved image. There may be something else going on that makes them inconsistent, and I am reading through things now.