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/catalogs/3/3044/

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III/44      Atlas of Stellar Spectra (Johnson 1977-1978)
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An Atlas of Stellar Spectra
    Johnson H.L.
    <Rev. Mex. Astron. Astrof. 2, 71 (1977)>
    =1977RMxAA...2...71J
    <Rev. Mex. Astron. Astrof. 4, 3 (1978)>
    =1978RMxAA...4....3J
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ADC_Keywords:  Spectrophotometry

Description:
   There are exactly 8192 spectral elements (points) in each spectrum,
   regularly spaced in terms of frequency. The first point corresponds to
   spectral frequency 0, while point number 8193 (not included) corresponds
   to the laser frequency. The 632.8nm laser frequency was doubled,
   producing an effective laser wavelength of about 316.4nm.
   Tentatively, it may be assumed that the exact laser wavelength is
   316.43nm.

   The spectra have been normalized so that the bluest stars are
   approximately level from 480 to 1000nm. The spectra are linear
   in intensity with zero intensity at tabulated zero. It was not
   possible to make satisfactory atmospheric extinction corrections
   throughout all of the atmospheric bands; at places where corrections
   could not be made, the spectra were set (exactly) to zero.

   Some of these spectra have been published already (H.L. Johnson,
   Rev. Mex. Astron. Astrof. 2, 71, 1977); the remainder will be
   published soon (Rev. Mex. Astron. Astrofis., 4, 3). These published
   spectral plots contain in graphical form the information needed to
   evaluate the signal-to-noise ratios of the spectra on this tape.
                            (From Harold L. Johnson, Dec. 13, 1977)

File Summary:
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  FileName   Lrecl    Records   Explanations
--------------------------------------------------------------------------------
ReadMe          80          .   This file
stars.dat       60         54   List of the stars
atlas.dat       74      55296   The Atlas (54 spectra)
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Byte-by-byte Description of file: stars.dat
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   Bytes Format Units   Label     Explanations
--------------------------------------------------------------------------------
   1-  2  I2    h       RAh       ? Right Ascension J2000 (hours) (1)
   4-  5  I2    min     RAm       ? Right Ascension J2000 (minutes) (1)
   7- 10  F4.1  s       RAs       ? Right Ascension J2000 (seconds) (1)
      12  A1    ---     DE-       ? Declination J2000 (sign) (1)
  13- 14  I2    deg     DEd       ? Declination J2000 (degrees) (1)
  16- 17  I2    arcmin  DEm       ? Declination J2000 (minutes) (1)
  19- 20  I2    arcsec  DEs       ? Declination J2000 (seconds) (1)
  24- 33  A10   ---     Name      Name of the star
  39- 42  I4    yr      Obs.Y     ? Observation date, year (2)
  44- 46  A3    "month" Obs.M     ? Observation date, month (2)
  48- 49  I2    d       Obs.D     ? Observation date, day (2)
  51- 52  I2    h       Obs.h     ? Observation date, hour (2)
      53  A1    ---     ---       [:]
  54- 55  I2    min     Obs.m     ? Observation date, minute (2)
  58- 60  I3    ---     Nobs      Number of observations.
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Note (1): the star position has been added at CDS
Note (2): The exact date is not specified when the spectrum is a mean
          of several observations.
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Byte-by-byte Description of file: atlas.dat
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   Bytes Format  Units   Label    Explanations
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   1- 10  A10    ---     Name     Name of the star
  11- 74  8I8    ---     I        8 Spectral elements (pixels); there are
                                    1024 lines per star. There are
                                    therefore 8192 points per spectrum. (1)
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Note (1): with the values assumed in the Description, the values of
    the wavenumbers, expressed in cm-1, are given by
        SIGMA(I) = 3.8577 * (I-1)
    and wavelength, in Angstroems, by
        WAVELEN(I) = 1.E8/(3.8577 * (I-1))
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(End)          Francois Ochsenbein [CDS]  28-Oct-1993, revised       02-Mar-1998