# Exposure.getReadoutCorner method returns incorrect values for some LSST CCD amplifiers.

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#### Details

• Type: Bug
• Status: Done
• Resolution: Done
• Fix Version/s: None
• Component/s:
• Labels:
None
• Story Points:
2
• Team:
Data Release Production
• Urgent?:
No

#### Description

The Exposure.getReadoutCorner() method used to determine the appropriate X/Y flips needed to properly orient two amplifiers to match returns the incorrect value for some amplifiers of the LSST CCD.

Ex: Both Segment C10 and Segment C00, which are on different sides of the CCD midline break return the same location for readout corner:



detector = exp.getDetector()
amp_top = detector['C10']
amp_bottom = detector['C00']



This is an issue for calculating crosstalk between amplifiers on opposite sides of the midline break as the orientation of the two pixel arrays obtained using lsst.ip.isr.CrosstalkCalib.extractAmp() is incorrect (see attached images).

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#### Activity

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Christopher Waters added a comment -

I believe I've tracked this to an issue in afw.  After doing all of the appropriate shifts and flips, the rawFlipX/Y parameters were set to False (as the flips had been done), but the readoutCorner was not.  I've added the appropriate changes to that now, and the attached image shows that the results of CrosstalkCalib.extractAmp now look correct.

Show
Christopher Waters added a comment - I believe I've tracked this to an issue in afw.  After doing all of the appropriate shifts and flips, the rawFlipX/Y parameters were set to False (as the flips had been done), but the readoutCorner was not.  I've added the appropriate changes to that now, and the attached image shows that the results of CrosstalkCalib.extractAmp now look correct.
Hide
Christopher Waters added a comment -

Jenkins success:

I've also attached the notebook for my check. ct-readoutCorners.ipynb

Show
Christopher Waters added a comment - Jenkins success: https://ci.lsst.codes/job/stack-os-matrix/35741/display/redirect   I've also attached the notebook for my check.  ct-readoutCorners.ipynb

#### People

Assignee:
Christopher Waters
Reporter:
Reviewers:
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