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legacysurvey / legacypipe

Image reduction pipeline for the DESI Legacy Imaging Surveys, using the Tractor framework
BSD 3-Clause "New" or "Revised" License
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Improve unWISE Catalog background around bright galaxies #653

Open schlafly opened 3 years ago

schlafly commented 3 years ago

The unWISE catalog produces a background model based on the median residual after subtracting point sources in a ~1x1' grid. This leads to ugly boxy residuals around galaxies with sizes comparable to 1'. We could probably eliminate this issue by excluding pixels marked as being in LSLGA ellipses from the background median filtering.

This approach carries a bit of risk. There will be more flux left on the images in the outskirts on galaxies; it's possible this could lead to more spurious sources. Alternatively, it may be reduce the number of sources found in these outskirts, since there will be fewer peaks to find after the poor background modeling is removed.

moustakas commented 1 year ago

Related to https://github.com/moustakas/SGA/issues/57.