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  1. Data Management
  2. DM-13227

Refine exposure-wide background subtraction

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    • Type: Story
    • Status: Done
    • Resolution: Done
    • Fix Version/s: None
    • Component/s: pipe_drivers
    • Labels:
    • Team:
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      Description

      The exposure-wide background subtraction (skyCorrection.py) can leave large negative residuals around bright sources when used with HSC (which sets the background scale to 1024 pixels). This can be mitigated by doing a more careful detection of faint extended structure, which was present in the prototype from NAOJ.

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            price Paul Price added a comment - - edited

            Including the detection gives much better results around the bright galaxy that Michitaro Koike identified as troublesome. The result is not perfect (it's still a bit over-subtracted), but it's MUCH better than before.

            Left: before, with no detection pass. Right: with a detection pass (detectSigma=5.0, detection.thresholdValue=3.0).

            Show
            price Paul Price added a comment - - edited Including the detection gives much better results around the bright galaxy that Michitaro Koike identified as troublesome. The result is not perfect (it's still a bit over-subtracted), but it's MUCH better than before. Left: before, with no detection pass. Right: with a detection pass ( detectSigma=5.0, detection.thresholdValue=3.0 ).
            Hide
            price Paul Price added a comment -

            Yusra AlSayyad, are you willing and able to review this small change?

            price@pap-laptop:~/LSST/pipe_drivers (tickets/DM-13227=) $ git sub
            commit 2371bd9e5fecb688854eca3f8ca7c525840ede89
            Author: Paul Price <price@astro.princeton.edu>
            Date:   Fri Jan 12 17:18:15 2018 -0500
             
                background: remove vestigial config parameter
                
                This config parameter was used in prototype implementations
                of the code, controlling features that no longer exist.
             
             python/lsst/pipe/drivers/background.py | 1 -
             1 file changed, 1 deletion(-)
             
            commit f0fb312068e2813aed1133f2694a29bf9ff493ed
            Author: Paul Price <price@astro.princeton.edu>
            Date:   Fri Jan 12 17:22:19 2018 -0500
             
                skyCorrection: refactor creation of focal-plane images
                
                Makes the binning factor configurable, and reduces boilerplate.
             
             python/lsst/pipe/drivers/skyCorrection.py | 32 ++++++++++++++++++++++++-------
             1 file changed, 25 insertions(+), 7 deletions(-)
             
            commit 48f04297f2613353685bfd4ea22355b6beef564d (HEAD -> tickets/DM-13227, origin/tickets/DM-13227)
            Author: Paul Price <price@astro.princeton.edu>
            Date:   Fri Jan 12 17:32:45 2018 -0500
             
                skyCorrection: detect sources to exclude from background model
                
                We use a wide matched-filter and relatively low threshold to pick
                up faint extended wings of bright sources. This reduces the
                over-subtraction around bright sources.
             
             python/lsst/pipe/drivers/skyCorrection.py | 49 +++++++++++++++++++++++++++++--
             1 file changed, 47 insertions(+), 2 deletions(-)
            

            Show
            price Paul Price added a comment - Yusra AlSayyad , are you willing and able to review this small change ? price@pap-laptop:~/LSST/pipe_drivers (tickets/DM-13227=) $ git sub commit 2371bd9e5fecb688854eca3f8ca7c525840ede89 Author: Paul Price <price@astro.princeton.edu> Date: Fri Jan 12 17:18:15 2018 -0500   background: remove vestigial config parameter This config parameter was used in prototype implementations of the code, controlling features that no longer exist.   python/lsst/pipe/drivers/background.py | 1 - 1 file changed, 1 deletion(-)   commit f0fb312068e2813aed1133f2694a29bf9ff493ed Author: Paul Price <price@astro.princeton.edu> Date: Fri Jan 12 17:22:19 2018 -0500   skyCorrection: refactor creation of focal-plane images Makes the binning factor configurable, and reduces boilerplate.   python/lsst/pipe/drivers/skyCorrection.py | 32 ++++++++++++++++++++++++------- 1 file changed, 25 insertions(+), 7 deletions(-)   commit 48f04297f2613353685bfd4ea22355b6beef564d (HEAD -> tickets/DM-13227, origin/tickets/DM-13227) Author: Paul Price <price@astro.princeton.edu> Date: Fri Jan 12 17:32:45 2018 -0500   skyCorrection: detect sources to exclude from background model We use a wide matched-filter and relatively low threshold to pick up faint extended wings of bright sources. This reduces the over-subtraction around bright sources.   python/lsst/pipe/drivers/skyCorrection.py | 49 +++++++++++++++++++++++++++++-- 1 file changed, 47 insertions(+), 2 deletions(-)
            Hide
            yusra Yusra AlSayyad added a comment -

            Looks good. See github for a question here and there.

            Show
            yusra Yusra AlSayyad added a comment - Looks good. See github for a question here and there.
            Hide
            price Paul Price added a comment -

            Thanks Yusra.

            Merged to master.

            Show
            price Paul Price added a comment - Thanks Yusra. Merged to master.

              People

              • Assignee:
                price Paul Price
                Reporter:
                price Paul Price
                Reviewers:
                Yusra AlSayyad
                Watchers:
                Michitaro Koike, Paul Price, Yusra AlSayyad
              • Votes:
                0 Vote for this issue
                Watchers:
                3 Start watching this issue

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                • Created:
                  Updated:
                  Resolved:

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