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J/A+AS/128/409      Wavelength calibration                     (De Cuyper+ 1998)
================================================================================
Wavelength calibration at moderately high resolution
     De Cuyper J.-P., Hensberge H.
    <Astron. Astrophys. Suppl. Ser. 128, 409 (1998)>
    =1998A&AS..128..409D      (SIMBAD/NED BibCode)
================================================================================
ADC_Keywords: Spectroscopy
Keywords: Methods: data analysis - Techniques: spectroscopic

Abstract:
    Thorium-Argon lamps are commonly used as wavelength calibration units
    at moderately high spectral resolutions because of the richness of the
    thorium spectrum in the visual. The inclusion of blended lines whose
    position is assumed to coincide with the laboratory wavelength of the
    main component is shown to result in a calibration precision
    significantly worse than the intrinsic random noise limit. In order to
    avoid this degradation of the calibration, we present
    resolution-dependent Th-Ar wavelengths in the region 277 to >1000nm
    for use at pixel-scales (pixel-size expressed in wavelength units)
    between {lambda}/2.5x10+4 and {lambda}/10+5.

File Summary:
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 FileName       Lrecl  Records   Explanations
--------------------------------------------------------------------------------
ReadMe             80        .   This file
table5a.dat       142    11906  *Principle table for the standard case of the
                                  argon-to-thorium line strength ratio
table5b.dat       142    11906  *Principle table for the argon rich case
table6.dat         36     8540   Selected lines
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Note on table5a.dat: I(ArI  430.01nm)/I(ThI 431.30nm) = 1.267
                     I(ArII 430.92nm)/I(ThI 430.72nm) = 1.922
Note on table5b.dat: I(ArI  430.01nm)/I(ThI 431.30nm) = 28.68
                     I(ArII 430.92nm)/I(ThI 430.72nm) = 43.48
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Byte-by-byte Description of file: table5a.dat table5b.dat
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   Bytes Format Units   Label     Explanations
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   1- 10  F10.4 0.1nm   Maincomp  Laboratory wavelength of the main component
  12- 15  A4    ---     Ion       Ion emitting the main component
  17- 21  F5.2  ---     Logint    Relative log intensity of the main component
  24- 33  F10.4 0.1nm   lam025000 ? Blend wavelength for R=25000
  35- 44  F10.4 0.1nm   lam033333 ? Blend wavelength for R=33333
  46- 55  F10.4 0.1nm   lam043700 ? Blend wavelength for R=43700
  57- 66  F10.4 0.1nm   lam050000 ? Blend wavelength for R=50000
  68- 77  F10.4 0.1nm   lam100000 ? Blend wavelength for R=100000
  79- 84  F6.3  pix     dp025     ? Displacement of the line for R=25000
  86- 90  F5.3  pix     s025      ? Discretisation stability of dp025 (1)
  92- 97  F6.3  pix     dp033     ? Displacement of the line for R=33333
  99-103  F5.3  pix     s033      ? Discretisation stability of dp033 (1)
 105-110  F6.3  pix     dp043     ? Displacement of the line for R=43700
 112-116  F5.3  pix     s043      ? Discretisation stability of dp043 (1)
 118-123  F6.3  pix     dp050     ? Displacement of the line for R=50000
 125-129  F5.3  pix     s050      ? Discretisation stability of dp050 (1)
 131-136  F6.3  pix     dp100     ? Displacement of the line for R=100000
 138-142  F5.3  pix     s100      ? Discretisation stability of dp100 (1)
--------------------------------------------------------------------------------
Note (1): The parameter s is the r.m.s. of the blend wavelengths calculated for
           20 different discretisations (sub-pixel locations of the line
           center) in steps of 0.05pix
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Byte-by-byte Description of file: table6.dat
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   Bytes Format Units   Label     Explanations
--------------------------------------------------------------------------------
   1-  6  I6    ---     R         Lambda/pixel-scale (1)
   9- 18  F10.4 0.1nm   Lambda    Pixel-scale dependent blend wavelength
  21- 30  F10.4 0.1nm   Maincomp  Laboratory wavelength of the main component
  33- 36  A4    ---     Ion       Ion emitting the main component
--------------------------------------------------------------------------------
Note (1): Where lambda is the wavelength, and pixel-scale is the pixel-size
            expressed in wavelength units
          R = 25000; 33333; 43700; 50000; 100000
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Acknowledgements:  Jean-Pierre De Cuyper <system@midasc.oma.be>
   Both authors carried out the research in the framework of projects initiated
   and financed by the Belgian Federal Scientific Services (DWTC/SSTC), under
   contract "Service Centres and Research Networks" nr. SC/005  and contract
   I.U.A.P. nr. P4/05.

References:
   Minnhagen L., 1973, J. Opt. Soc. Am. 63, 1185
   Norlen G., 1973, Phys. Scripta 8, 249
   Palmer B.A., Engleman R. Jr., 1983, "Atlas of the Thorium Spectrum",
       ed. H. Sinoradzky (Los Alamos National Laboratory)
================================================================================
(End)                               Jean-Pierre De Cuyper[KSB/ORB]   15-May-1997