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PostPosted: 28. September 2018, 23:08:04 PM 
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Meister
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Joined: 11. November 2007, 18:11:30 PM
Posts: 1310
Hallo,
über Centroide von Spektrallinien wurde hier bereits diskutiert. Daher möchte auf folgende Arbeit hinweisen:
Teague Foreman-Mackey,
A robust method to measure centroids of spectral lines
https://arxiv.org/pdf/1809.10295.pdf
Viele Grüße
Christian


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PostPosted: 30. September 2018, 14:47:53 PM 
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Meister
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Joined: 25. October 2006, 23:43:13 PM
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Location: Cumbria England
Hello Christian,

I find this very counter-intuitive. They are suggesting that they can get a better estimate of the centroid by ignoring 80% of the data (~12/15 data points in their example line profile), independent of the line shape or SNR. I find this difficult to believe. For example in an oversampled line with a broad top, a small amount of noise could change the location of the maximum pixel giving a large error

Cheers
Robin


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PostPosted: 01. October 2018, 12:01:46 PM 
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Meister
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Joined: 11. November 2007, 18:11:30 PM
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Hello Robin,
my intuition says that you are right.
Cheers
Christian


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PostPosted: 01. October 2018, 15:57:31 PM 
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Meister
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Joined: 31. July 2006, 16:43:32 PM
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Location: Köln
Robin is right! This paper is clearly not addressed to velocity measurements in stellar environments (especially lines from expanding winds). They rather apply it to radio observations with sharp lines (their model example uses Gaussians).
Cheers, Thomas


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