observer/iue_quasar_atlas/README

     The two files currently present in this directory are
the digital versions of the spectra that were extracted and
co-added for the Utraviolet Altas of Quasar and Blazar
Spectra, 1991, Astrophysical Journal Supplement, Volumn 75,
p. 645 by Kinney, A.L., Bohlin,R.C., Blades, J.C., and York,
D.G.

     There are two copies available; Atlas.5line and Atlas.opt.
The Atlas.5line version contains the simple boxcar extraction 
that is actually used for the spectra presented in the paper. 
The suffix 5line refers to the number of lines in the line-by-line 
file added to produce each individual specturm.  The Atlas.opt 
file contains the optimally extracted co-added spectra.  The 
optimal extraction is described in a paper which is in press at 
P.A.S.P. and is available upon request to the authors (Kinney, 
Bohlin, and Neill at STScI).  

     The file formats are mostly self explanatory. THE S-AP NOMENCATURE 
INDICATES THE SPECTRA THAT ARE NORMALIZED IN FLUX TO THE L-AP SET 
(USUALLY ONE SPECTRUM, see paper for a more detailed explanation) AND 
DOES *NOT* MEAN THAT THE SPECTRA WERE OBTAINED IN THE SMALL ENTRANCE 
APERTURE.  The camera numbers of co-added spectra are listed.  Each 
co-added spectrum has 8 columns of ASCII numbers with the
titles LAM=wavelength (AA), EPS=quality flag, GROSS=gross (flux numbers), 
BKG=background (flux numbers), NET/TIME=gross-background divided by time, 
ABNET=absolute calibrated net flux (ergs/cm2/s/A), TIME(sec),
SIGMA (percent- example; 2.1 = 210 percent).  In the case of the .5line 
file, the sigma is the RMS scatter among the coadded  spectra at 
each wavelength, while the sigma for the .opt file represents the 
error in the mean, as estimated from the IUE noise models that we have 
constructed.

Contact Anne Kinney for additional information.