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  1. Data Management
  2. DM-13553

Deal with large blends



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      With the sky correction (DM-9147, DM-13388), perhaps combined with the lower detection threshold (DM-12295), we are getting many large parent objects (> 10^6 pixels), deblending which is a burden on our compute budget. In several cases, this appears to be due to scattered light surviving the coadd process.

      jbosch has proposed that we do a modest-scale background subtraction before detection, which should break up the large footprints; then we will restore the background before deblending so that the measurements have access to the original (good, large-scale) sky subtraction. There's a question about what scale to use in the background subtraction, which we can determine by running detection with different background subtraction scales, and seeing where we drop below the footprint size limits we've set in the deblender.

      Jim also noted that after detection, we grow footprints by the size of the PSF in our standard detection routine. Instead of growing them all at once and allowing them to merge as we currently do, he suggests growing them individually, allowing the footprints to overlap but not merge. This might also help keep the large chains from forming.


        Issue Links


            price Paul Price created issue -
            price Paul Price made changes -
            Field Original Value New Value
            Link This issue is triggered by DM-9147 [ DM-9147 ]
            price Paul Price made changes -
            Link This issue is triggered by DM-13388 [ DM-13388 ]
            price Paul Price made changes -
            Link This issue is triggered by DM-12295 [ DM-12295 ]
            price Paul Price made changes -
            Attachment checkDeblending.py [ 32012 ]
            yusra Yusra AlSayyad made changes -
            Link This issue contains DM-13563 [ DM-13563 ]
            price Paul Price made changes -
            Component/s meas_algorithms [ 10732 ]
            Component/s obs_base [ 10719 ]
            price Paul Price made changes -
            Resolution Done [ 10000 ]
            Status To Do [ 10001 ] Done [ 10002 ]


              price Paul Price
              price Paul Price
              Hisanori Furusawa, Hsin-Fang Chiang, Jim Bosch, Masayuki Tanaka, Paul Price, Robert Lupton, Yusra AlSayyad
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