Fix Version/s: None
Team:Data Release Production
Dear Paul-san, Jim-san, and all,
As we discussed before, I am reviewing the defect masks which are set
in singleFrameDriver.py. I realized the singleFrameDriver.py produces
very high values in area masked by defect list, especially for CCD=33
that has a large defect area. Such high values around the CCD edges
sometimes cause undesired streaks surviving on coadd images.
See the attached figure (stripes_z_101092_101096.jpg) (left: coadd in
a patch, middle: a warp in the same coordinates, right: another warp).
In the warp figures, light green areas corresponds to the defects. We
see that streaks on coadd presumably caused by the outlying values
around the CCD edges due to defects mask. Particularly, the largest
rectangular green is for the defect mask of CCD=33, which covers
neighboring 2 channels. For reference, I also attached snapshots of
CORR images for CCD=33 and 0, where CCD=33 has a large defect area on
the entire left-handed side of the pixels, and CCD=0 has a 1-channel
defects located between the healthy ch-1 and 3.
The defect on CCD=0 seems to be somehow interpolated, but CCD=33's
seems to be disturbed.
These resultant (high) values are undesired themselves, but if the
mask bit (BAD) works perfect, those would be eliminated on coadds, and
that should be ok. However, the actual coadd shows some fraction of
(CCD gaps are filled by NaN on warps, and those seem to be decently
clipped by coadds).
Note that CCD=33 is the most prominent CCD that causes the present
problem, but the other CCDs are also set defect masks around the edges
and middle of the CCD.
I think we want to gently ignore pixels masked by defect list, rather
than having such high and regular values, or reasonably interpolated
or filled with more harmless value.
Also mask bit should cover these defect area on coadds more carefully?
I think this is a relatively highly demanded fix, but understand time
Do you have ideas of something we could try to track down this issue
before going into the upcoming production?