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: pipe_analysis
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Labels:None
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Story Points:6
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Epic Link:
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Sprint:DRP F18-1, DRP F18-2, DRP F18-3, DRP F18-4, DRP F18-5
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Team:Data Release Production
Description
Add the P1/P2 "Principal Color" axes (à la Ivezić et al. 2004AN....325..583I) to the stellar color-color plots.
In more detail, for each principal color, we compute the mean offset and standard deviation for the wired "canonical" coeffecients to the P2 and P1 axes. We also fit for these for the given data. These two sets of axes should be added to the color-color plots as they provide useful information about the stellar locus/populations. A shift of the P1 line would indicate a fundamental shift in the color "locus", whereas a shift in the P2 axis indicates a shift in the position of the highest density of stars which is how the origin of the P1/P2 plane is selected (i.e. this would not likely consist of a fundamental "offset" in the colors, but rather be reflective of the distribution of stars along that particular pointing. Such a shift does not affect the mean or standard deviation in the statistics shown on the histograms).
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Would you mind giving this a look? It is based off the DM-13519 ticket branch (which is still waiting on a review), so I have not made a PR. Feel free to punt on this until DM-13519 gets merged so that this can be rebased onto master with a proper PR, but in case you have a spare moment, the commits for this ticket start at Update plotText to allow coordinate system selection and there are seven commits in total.
Thanks for the review! I've addressed your comments on the PR. I'll give you some time to make sure you're ok with everything now.
Looks good!
Updated plots run on the w_2018_22 HSC RC2 reprocessing run can currently be found here:
https://lsst-web.ncsa.illinois.edu/~lauren/lauren/DM-14826/w_2018_22/
and I attach two specific examples. This one for the WIDE_GAMA15H field shows the "wired" and "fit" wPerp coefficients and P1/P2 axes are the same – this is because the "wired" fits are based on this field.
The UD_COSMOS field shows an offset in the P1/P2 origin due to the slightly shifted location of maximum point density here compared to the GAMA15H field, but the P2 line is almost indistinguishable. Thus, there is a slight (3mmag) offset between the fit and wired fits, but the standard deviation (the most relevant diagnostic) is barely affected.