file: readme_fts_intens.txt = README with NSO FTS intensity atlas
last: May 25 1999
from: ftp://ftp.noao.edu/fts/visatl/
note: - year of publication?
      - disk center?
      - no absolute units?
      - wavenumbers, wavelengths need vacuum to air shift

subdirectory visatl: Contains an on-line version of ``An Atlas of the 
Spectrum of the Solar Photosphere from 13,500 to 28,000 cm-1 (3570 to 
7405A)'' (N.S.O. Technical Report #98-001, June 1998) by L. Wallace, K. 
Hinkle, and W. Livingston. Both data files and postscript plots are 
available.



          An Atlas of the Spectrum of the Solar Photosphere
             from 13,500 to 28,000 cm-1 (3570 to 7405A)

              L. Wallace, K. Hinkle, and W. Livingston,
              National Optical Astronomy Observatories.

The files collected here were made in conjunction with, and
are intended to be used with, the hard copy of this atlas.  The files
with the prefixes "sp" contain the spectral data from which the plots
were made.  Each of these contains a 50 cm-1 region with a 3 cm-1
overlap on each end.  Following the prefix "sp" is the lead frequency
of the segment, e. g., "14150".  

For the region 13,500 to 20,000 cm-1, the four columns of each file
contain, first the frequency, second the deduced telluric spectrum,
third the observed photospheric spectrum before correction for
telluric absorption, and fourth the photospheric spectrum corrected
for telluric absorption.  

The region 20,000 to 28,000 cm-1 contains no sensible narrow-line
telluric absorbers and consequently the files contain only the
frequencies and the observed spectrum.  The required multiplicative
factors to correct the observed frequencies to the laboratory scale
are 1.0000013 for 13,500 to 16,000 cm-1, 0.9999981 for 16,000 to
20,000 cm-1, and 1.0000018 for 20,000 to 28,000 cm-1.  

The remaining files are  encapsulated post-script files, one per atlas
page.  The prefix "ph" indicates the corrected photospheric spectra in
Section II  of the atlas.   The "tr" files  are the Section  III pages
giving atmospheric transmission and the observed photospheric spectra.
Finally,  "cph"   and  "ctr"  are  the   compressed  photospheric  and
transmission plots of Section I.