[PIPE2D-1111] Extremely large wavelength difference of the detector map adjusted with few sky lines. Created: 08/Nov/22 Updated: 29/Nov/22 Resolved: 29/Nov/22 |
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| Status: | Done |
| Project: | DRP 2-D Pipeline |
| Component/s: | None |
| Affects Version/s: | None |
| Fix Version/s: | None |
| Type: | Bug | Priority: | Normal |
| Reporter: | Satoshi Hamano | Assignee: | price |
| Resolution: | Done | Votes: | 0 |
| Labels: | None | ||
| Remaining Estimate: | Not Specified | ||
| Time Spent: | Not Specified | ||
| Original Estimate: | Not Specified | ||
| Attachments: |
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| Reviewers: | hassan |
| Description |
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pfs_pipe2d version: w.2022.43 The detector map adjusted with very few sky lines shows the large wavelength difference (>1 nm for arm 'b' of the SuNSS data) from the wavelength solution in the original detector map before adjustment.
An example of the SuNSS data (arm b of visit=80906 obtained in 2022-10-05) is shown below. Only a few sky lines are detected in the image of arm b. Especially, there is no sky lines seen in the blue side (lower side in the attached calExp image).
When this image is reduced with reduceExposure.py using the reduced calibration data prepared in 2022-06-30, the wavelength solution in the adjusted detector map shows a very large difference from that of the original detector map. Below image shows the wavelength difference between the detector maps (the original wavelength solution was subtracted from the adjusted wavelength solution). The wavelength difference is larger than 1 nm in the red side of the detector.
When these two detector maps are compared with the Ar lamp image (visit=79997 obtained in 2022-09-25), the original detector map matches well with the detected Ar line positions. In the below image, the positions of Ar lines in the detector map are plotted with dots (red: the detector map adjusted with SuNSS data, blue: the original detector map) over the calExp image of Ar lamp data shown with gray scale. Only bottom quarter of the image, where the wavelength difference is quite large, is shown here. Other three quarter images are attached to this ticket.
Therefore, the adjustment of the detector map seems to fail in the region where very few or no sky lines are detected.
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| Comments |
| Comment by price [ 09/Nov/22 ] |
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What version of the calibs are you using? |
| Comment by price [ 09/Nov/22 ] |
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Oh, it looks like you're using CALIB-20220630. |
| Comment by Satoshi Hamano [ 09/Nov/22 ] |
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Yes, I used 'CALIB-20220630'. |
| Comment by price [ 10/Nov/22 ] |
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I've made some fixes to obs_pfs and drp_stella that I think improve the measurement of the centroids and the fitting of the detectorMap adjustment. I'd appreciate your evaluation of the results. Please keep in mind that while the size of the change to the detectorMap might be a hint to the quality of the adjustment, we are more interested in the accuracy with which the adjusted detectorMap reproduces the x,y positions. That's difficult to measure at the blue end of the blue arm with sky data, so maybe the size of the change is mostly all we have to work with. But knowing the changes is not useful without some idea of what they should be. |
| Comment by Satoshi Hamano [ 11/Nov/22 ] |
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Please ignore the two attached png files I uploaded about an hour ago. It's a mistake. I couldn't delete them. |
| Comment by Satoshi Hamano [ 11/Nov/22 ] |
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I checked the result of reduceExposure.py in the branch of "tickets/ |
| Comment by price [ 23/Nov/22 ] |
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I finally reached a conclusion that I'm satisfied with. The lack of CR masking before detectorMap adjustment was generating a lot of garbage trace centroids that were causing many of the good, solid measurements of sky lines to be rejected. With CR masking before detectorMap adjustment, we get much better fits, and a more uniform shift in both xCenter and wavelength. reduceExposure.adjustDetectorMap INFO: Final result: chi2=4360.657959 dof=3723 xRMS=0.051719 yRMS=0.055085 xSoften=0.028748 ySoften=0.000000 from 2894 lines reduceExposure.adjustDetectorMap INFO: Stats for NaI: chi2=733.738466 dof=872 xRMS=0.062353 yRMS=0.074312 xSoften=0.000000 ySoften=0.000000 from 436 lines reduceExposure.adjustDetectorMap INFO: Stats for OH: chi2=0.000000 dof=0 xRMS=nan yRMS=nan xSoften=0.000000 ySoften=0.000000 from 0 lines reduceExposure.adjustDetectorMap INFO: Stats for OI: chi2=629.056168 dof=834 xRMS=0.037867 yRMS=0.044958 xSoften=0.000000 ySoften=0.000000 from 417 lines reduceExposure.adjustDetectorMap INFO: Stats for Trace: chi2=2997.863325 dof=2041 xRMS=0.052885 yRMS=nan xSoften=0.043437 ySoften=0.000000 from 2041 lines
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| Comment by hassan [ 23/Nov/22 ] |
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Changes look fine. Minor comment on refactoring added to pull request. |
| Comment by price [ 29/Nov/22 ] |
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Refactored as suggested, and merged. |