This page (revision-12) was last changed on 07-Dec-2016 14:14 by David R Williams

This page was created on 09-Jul-2007 12:35 by JianSun

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Page revision history

Version Date Modified Size Author Changes ... Change note
12 07-Dec-2016 14:14 2 KB David R Williams to previous Took out the discussion about FWHM versus natural width because it was confusing. Result now summarised.
11 22-Jan-2009 05:36 4 KB David R Williams to previous | to last Reply to comment by Celine Boutry, and correction to the description of the instrumental width.
10 21-Jan-2009 15:12 3 KB CelineBoutry to previous | to last
9 21-Jan-2009 09:00 2 KB David R Williams to previous | to last
8 21-Jan-2009 09:00 2 KB David R Williams to previous | to last
7 21-Jan-2009 08:59 2 KB David R Williams to previous | to last
6 21-Jan-2009 08:58 2 KB David R Williams to previous | to last Response to Celine Boutry's question about the instrumental width.
5 21-Jan-2009 08:47 2 KB David R Williams to previous | to last
4 16-Jan-2009 15:36 1 KB CelineBoutry to previous | to last instrumental width
3 09-Jul-2007 13:00 955 bytes Louise Harra to previous | to last
2 09-Jul-2007 12:36 1 KB JianSun to previous | to last
1 09-Jul-2007 12:35 1 KB JianSun to last

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InstrumentalWidthOfEIS...nobody
InstrumentalWidthOfEIS

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About the instrumental width, [Doschek et al 2007|http://adsabs.harvard.edu/abs/2007ApJ...667L.109D] proposed a FWHM of 2.5 pixels (i.e. 56 mA) in orbit given that the FWHM is 1.956 pixels in laboratory and [Brown et al. 2008|http://adsabs.harvard.edu/abs/2008ApJS..176..511B] give us between 54mA and 57mA depending on the wave band and the wavelength.\\
Is there any instrumental profile available?\\
Is it a Gaussian profile? What is the width commonly used ?\\
--[Celine Boutry], 16-Jan-2009
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Hi Céline,
I think the answer may be in your question, actually.
The Doschek ''et al.'' article states a single number, but that is based on comparisons with older data. However, it is still consistent with the numbers derived from comparing the pre-launch laboratory EIS calibration data with the on-orbit EIS data by Brown ''et al.'' (2008). The Brown ''et al.'' numbers are inferred widths, but the reasoning is pretty logical; the fact that the Doschek ''et al.'' (2007) number falls within that range of 0.054 — 0.057 Å is comforting.
In summary, Brown ''et al.'' (2008) assume a Gaussian instrumental line profile, and they infer an instrumental width of 0.054 Å in the short-wavelength channel (170 — 210 Å) and 0.057 Å for the long-wavelength channel (250 — 290 Å).
__NOTE!__ As Céline Boutry points out, this is the FWHM of the instrumental width (not the Gaussian width σ as previously incorrectly stated here).
--[Dave Williams|DavidRWilliams], 17-Jan-2009
This page (revision-12) was last changed on 07-Dec-2016 14:14 by David R WilliamsTop