# Fix rotation for isr in obs_subaru

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## Details

• Type: Bug
• Status: Done
• Resolution: Done
• Fix Version/s: None
• Component/s:
• Labels:
None
• Story Points:
2
• Sprint:
Science Pipelines DM-W16-6
• Team:
Data Release Production

## Description

Approximately half of the HSC CCDs are rotated 180 deg with respect to the others. Two others have 90 deg rotations and another two have 270 deg rotations (see HSC CCD layout) . The raw images for the rotated CCDs thus need to be rotated to match the rotation of their associated calibration frames prior to applying the corrections. This is accomplished by rotating the exposure using the rotated context manager function in obs_subaru's isr.py and the nQuarter specification in the policy file for each CCD. Currently, rotated uses afw's rotateImageBy90 (which apparently rotates in a counter-clockwise direction) to rotated the exposure by 4 - nQuarter turns. This turns out to be the wrong rotation for the odd nQuarter CCDs as shown here:

top left = raw exposure as read in
top right = flatfield exposure as read in
bottom left = incorrectly rotated raw exposure prior to flatfield correction

## Attachments

1. ccd100_nQuarterFix.png
895 kB
2. ccd100_nQuarter3.png
257 kB

## Activity

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Lauren MacArthur added a comment -

Bob, could you have a look at this? I have confirmed the fix for all rotations and show an example of the fix for ccd 100 here (left panel is with the fix, right is without)

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Lauren MacArthur added a comment - Bob, could you have a look at this? I have confirmed the fix for all rotations and show an example of the fix for ccd 100 here (left panel is with the fix, right is without)
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Bob Armstrong added a comment -

I'm fine with these changes, given that, as we talked about last week, it is only a temporary solution to make things agree between HSC and LSST.

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Bob Armstrong added a comment - I'm fine with these changes, given that, as we talked about last week, it is only a temporary solution to make things agree between HSC and LSST.
Hide
Lauren MacArthur added a comment -

I think you meant to say "Review Complete" (as opposed to "Done").

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Lauren MacArthur added a comment - I think you meant to say "Review Complete" (as opposed to "Done").
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Lauren MacArthur added a comment -

For completeness' sake, since obs_subaru is now built as part of CI in Jenkins, I ran a build, which was successful. Merged to master.

Show
Lauren MacArthur added a comment - For completeness' sake, since obs_subaru is now built as part of CI in Jenkins, I ran a build, which was successful. Merged to master.

## People

• Assignee:
Lauren MacArthur
Reporter:
Lauren MacArthur
Reviewers:
Bob Armstrong
Watchers:
Bob Armstrong, John Swinbank, Lauren MacArthur