# Ignore EDGE pixels in coaddition

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## Details

• Type: Story
• Status: Done
• Resolution: Done
• Fix Version/s: None
• Component/s:
• Labels:
• Team:
External

## Description

In the HSC detectors, charge can pool at the top/bottom of the device. The level (~ 20k) is significantly under the saturation level, so it doesn't get masked and there's no simple way to identify it. Without ignoring EDGE pixels during coaddition (removed in DM-9953), these bad pixels leak into the coadds. We need to revert commit 5faadffd2f408b019280ea1c353f0ec787b092b9.

## Activity

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Paul Price added a comment -

 price@pap-laptop:~/LSST/obs_subaru (tickets/DM-12931 $%=)$ git sub commit 42b43ff7eab451b469faa33b83eca4ef0d5a95db (HEAD -> tickets/DM-12931, origin/tickets/DM-12931) Author: Paul Price  Date: Wed Dec 6 15:56:42 2017 -0500    Revert "config: allow EDGE pixels to be coadded"    This reverts commit 5faadffd2f408b019280ea1c353f0ec787b092b9.    We've identified a reason to ignore EDGE pixels in the coadd:  the charge from saturated sources can pool at the top/bottom  of the detector. This charge is at a level (~20k) significantly  below saturation, so it's difficult to identify cleanly. Tossing  all pixels around the edge of the image is the easiest way to  ensure these don't leak in.    config/assembleCoadd.py | 2 +-  config/safeClipAssembleCoadd.py | 2 +-  2 files changed, 2 insertions(+), 2 deletions(-) 

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Paul Price added a comment - price@pap-laptop:~/LSST/obs_subaru (tickets/DM-12931 $%=)$ git sub commit 42b43ff7eab451b469faa33b83eca4ef0d5a95db (HEAD -> tickets/DM-12931, origin/tickets/DM-12931) Author: Paul Price <price@astro.princeton.edu> Date: Wed Dec 6 15:56:42 2017 -0500   Revert "config: allow EDGE pixels to be coadded" This reverts commit 5faadffd2f408b019280ea1c353f0ec787b092b9. We've identified a reason to ignore EDGE pixels in the coadd: the charge from saturated sources can pool at the top/bottom of the detector. This charge is at a level (~20k) significantly below saturation, so it's difficult to identify cleanly. Tossing all pixels around the edge of the image is the easiest way to ensure these don't leak in.   config/assembleCoadd.py | 2 +- config/safeClipAssembleCoadd.py | 2 +- 2 files changed, 2 insertions(+), 2 deletions(-)
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Jim Bosch added a comment -

Looks good!

(I also took the time to re-make that coadd and check both that the feature were gone and that the SENSOR_EDGE masking isn't, so there's no need to do that yourself - I had 99% of the command-line ready to go from testing I did on DM-12933).

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Jim Bosch added a comment - Looks good! (I also took the time to re-make that coadd and check both that the feature were gone and that the SENSOR_EDGE masking isn't, so there's no need to do that yourself - I had 99% of the command-line ready to go from testing I did on DM-12933 ).
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Paul Price added a comment -

Thanks Jim.

Merged to master.

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Paul Price added a comment - Thanks Jim. Merged to master.

## People

• Assignee:
Paul Price
Reporter:
Paul Price
Reviewers:
Jim Bosch
Watchers:
Jim Bosch, Paul Price