[PIPE2D-146] Describe issues around building line lists Created: 10/Jan/17  Updated: 15/Apr/17  Resolved: 15/Apr/17

Status: Done
Project: DRP 2-D Pipeline
Component/s: None
Affects Version/s: None
Fix Version/s: None

Type: Story Priority: Major
Reporter: swinbank Assignee: aritter
Resolution: Done Votes: 0
Labels: None
Remaining Estimate: Not Specified
Time Spent: Not Specified
Original Estimate: Not Specified

Story Points: 1
Sprint: 2014-17

 Description   

aritter's work on wavelength calibration for LAM (yet to be ticketed) stalled due to difficulties in creating appropriate line lists. However, at our meeting of 2017-01-09, it was a little vague what those difficulties were. Please provide a brief description of the procedure followed and why it proved so time consuming.



 Comments   
Comment by aritter [ 15/Apr/17 ]

We want to create line lists for any possible combination of arc lamps. As input line lists I use the data from the NIST Atomic Database for the individual lamps. The problem is to remove lines from the combined line list which are blended, asymmetric, or else flagged as problematic. Removing blended lines not as easy as it might seem. If one line in the blend is much stronger than the other line(s) then we want to keep the strong line in the list as it should not be affected much by a weak line. My approach to creating a combined line list is as follows:

  • Search the combined line list for possible blends and remove either all lines in the blend if they are of similar strength, or remove only the week line(s) in the blend in case the strong line is significantly (orders of magnitude) stronger
  • Remove all lines which are flagged as problematic
  • Create an approximate line list [pixel, wavelength] from the predicted pixel vs. wavelength file
  • Measure the shape of the remaining lines and remove remaining possible blends as well as lines which do not show up in the spectrum
    I believe that I was pretty close to getting a reliable procedure running when I stopped working on it.
Comment by swinbank [ 15/Apr/17 ]

At our meeting of 2017-04-14, we agreed that the above would do for now, and we'll press ahead with PIPE2D-139. Andreas will provide detailed reports on any problems he encounters on that ticket.

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