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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Round sersic end up as Rex #684

Open DriftingPig opened 3 years ago

DriftingPig commented 3 years ago

Hi Dustin, I did a test of adding sersic galaxies to empty image, and also setting the weight map super high to check if the sersic galaxies converge to its model in this perfect condition. And when serisc<2, e=0, these round sersic end up as Rex galaxies. It does not happen when sersic>2. In the attached plot, each red dot represents a sersic galaxy, and every 4 of them has e=0. I checked the dchisq columns, it does not go to fit the sersic profiles. I think it's because Rex has a better chisq than EXP/DEV, so it does not go to fitting sersic stage and ends up being a REX galaxy instead. download