[INSTRM-1391] Theoretical cobra centers are not correct Created: 12/Oct/21  Updated: 26/Oct/21  Resolved: 26/Oct/21

Status: Done
Project: Instrument control development
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Task Priority: Normal
Reporter: hassan Assignee: chyan
Resolution: Done Votes: 0
Labels: EngRun
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Attachments: PDF File cobraRotationCenter.pdf     Zip Archive ffdata.zip     Zip Archive ffdata.zip     Text File fiber_status_summary_20C90D.txt    
Issue Links:
Blocks
blocks INSTRM-1388 Poor convergence quality during Sep 2... Done
Relates
relates to INSTRM-1395 Some fiducial fibers are not found Done
Story Points: 2
Sprint: EngRun3Cleanup
Reviewers: hassan

 Description   

As identified during the Engineering Run post-mortem telecon 2021-10-04 (https://sumire.pbworks.com/w/page/146399862/Commissioning%20telecon%20on%20Oct%206%202021%20%28Wed%29%203%3A30%20UTC), the theoretical cobra centers provided as input did not match those measured.

Please find the cause and fix.

Comment form rhl:

I still don't understand how this will affect convergence unless the positions are very off. Chi-Hung re-measured the centroids from the theta moves early in the run, so does this mean that we need to debug/fix that code?

It would be good to encapsulate that code in an fps command. We should make sure that we have proper visualisation of the results too, including the results of Chi-Hung's analysis that shows that the current values aren't all quite right.

 Comments   
Comment by chyan [ 21/Oct/21 ]

I have uploaded the rotational center analysis. According to the analysis, there are +/-20 micron difference in rotational center and XML file. The center in XML needs to be updated. Before, updating the XML, a suggesting is also raised in meeting, which is using sigma-clipping for circle fitting. So that, we can avoid the problem when cobra spot is hidden by dots. A function called filter_circle_fitting in {{ ics.cobraCharmer.procedues.moduleTest.calculus}} was implemented. However, the filter threshold needs to fine tune.

cobraRotationCenter.pdf

Comment by chyan [ 22/Oct/21 ]

Those are related to the transformation issue.

Comment by chyan [ 22/Oct/21 ]

I went through the file I sent to Robert during the observation run (see attached file fiber_status_summary_20C90D.txt). There are 91 entries for FFs and the measurement were done at 20 degree C at EL90. However, there are updated measurements under 0 and 20 degree C and at different EL angle.

Comment by hassan [ 22/Oct/21 ]

Could you possibly describe what each column in the file fiber_status_summary_20C90D.txt corresponds to please chyan?

Comment by chyan [ 26/Oct/21 ]

I think the only useful information is column 1,4,5, which are FF id, x and y in mm.

Comment by chyan [ 26/Oct/21 ]

I have generated a new XML with updated centers based on new measurements. We should use this updated one for coming test. I updated the XML in pfs_insdata.

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