[Keith Shank]

Robin thanks for the information and especially the great news for the update of Demetra for the LISA!   I do not have this version, and am very happy to see it available!   I had watched the replay of the Shelyak session thanks for the link and it is seen that there are still some items to work through on the sw.   I will try out this new version and come back.

David gave me some great info on limiting the spectral lines used as a base to use for the LISA calibration on Demetra (previous version) and that worked very well getting me an RMS .173 which is quite acceptable.   I have tried this on several images with similar results but now, with the new version of Demetra I will see what happens.

Thanks will hope to test tonight, we have been getting summer monsoons here the last week, but it looks like that is over now and we can get back to our more normal dry  & hot….

Thanks for the help, much appreciated!

Keith

[Keith Shank]

Thanks Robin for the good info on creating a comparison quality assessment.   I will use this as a framework to build my capability to the level needed.   I found that I had several issues with the initial setup of Demetra, and a misunderstanding on how to use the reference stars to create a response curve.

Among the learning curve issues that I have resolved or managed to understand 

– I had incorrectly set the zones in the target images for the spectrum response (too wide of a strip), and the background noise (too small of a region of the image).  Once I reset those, my SNR improved significantly and the results improved.

– Calibration – still having problems in getting Demetra to ‘automatically’ recognize the calibration image and to properly assign the right spectral line.  When I use ‘automatic’ I cannot get better than 2.4 RMS, where if I go in an manually set the lines to the image (5852, 6562, 6965, 7067, 7383) my calibration gets a very good .2-.8 RMS.  The software may not be at fault.  I develop platforms, and told one user ‘it’s idiot proof’… he confidently told me ‘you dont have the right idiots’…..

– Response: I was mistaken on how to use /implement the response curve.  I thought I was to take an image of a ‘reference star’ after imaging each ‘target star’.   Then use that image to create a response curve.  I thought I was supposed to use the MILES (or Pickles) db to create a ‘response curve’ from the image of the ‘Reference Star’ by smoothing it from the MILES/Pickles db.  Then apply that curve to the image of my ‘Target star’.   I could not figure out how to apply that response curve to the ‘Target star’ in Demetra.  However after some great info from the team here on BAA, I have been using just the B/A type reference star (derived from the spreadsheet) to create that  smoothed ‘response curve’ directly from the MILES db onto my ‘Target star’. 

Although I am not to the high quality results I am wanting yet, I am consistently starting to see results close to those on the BAA site.   

Still learning a lot, and not quite to the levels to make any good sense from a test as you propose, as I want my results on a singular basis to be angstrom level accurate before I move to the next step (some targets <.5a others >2a depending on where in the spectrum)…   So working on this repeatability now. 

Always appreciative of any new suggestions, will keep pushing on this path. 

Thanks

Keith

[Keith Shank]

David,

Thanks very much for the kind response and good information.  Yes exactly the Balmer lines were not in the right location, I think your response just gave me the insight I needed to move forward.  I was mis-using the software as I suspected.   Ok so take my data of the reference star and use the on-line resources to create a smoothed instrument result.  I was using the on-line resource to create that smoothed result directly.   At least that is the first step, and explains the impact.  Also getting an idea of the right RMS value is of great help!   More to learn for sure, and will always appreciate guidance.

Also thanks for the connection to Woody, he has already contacted me, and I am very happy to have that connection!   

Glad to be a beginner part of this group, looking forward to future growth here!

Regards,

Keith

[Keith Shank]

NOTE:   The Arcturus image was before calibration, n it got put in by mistake so please ignore.

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