over-subtraction of Mosaic3 z-band imaging about sga

[dstndstn]

Yes, we're very aware of this issue. The Mosaic3 camera has pattern noise, and these artifacts arise from the algorithm that tries to remove it.

[siyue]

Thanks! just learn more about this infuriating noise! Then I will remove all these galaxies from my sample. If I may make a comment, I would suggest making this potential problem explicit in the SGA's description!

[moustakas]

@siyue, yes, this issue is frustrating and was also flagged here as it has impacted my intracluster light work, too--
legacysurvey/legacypipe#666

I agree that we should add a note to the "Known Issues" page.

[siyue]

YES! They are too green!! This is also how I found the problem!!