Description of the Sawyer Asteroid Spectra bundle V1.0
======================================================

Bundle Generation Date: 2023-02-03
Peer Review: Neese_Richardson_Mueller_Migration
Discipline node: Small Bodies Node


Content description for the Sawyer Asteroid Spectra
bundle
==========================================================

Note: This
bundle was migrated to PDS4 from the PDS3 data
set
EAR_A_3_RDR_SAWYER_ASTEROID_SPECTRA_V1_2.  For PDS3 data sets migrated to
PDS4,
the following text is taken verbatim from the data set description
and
confidence level note of the PDS3 data set catalog file. In these cases,
some
details may not be correct as a description of the PDS4 bundle.           


This data set contains 94 asteroid spectra obtained by Scott Sawyer as part
of
his Ph.D. dissertation at the University of Texas at Austin.             
  


 Parameters                                                                


==========                                                               

Each
spectrum is contained in a separate file, listing wavelength and
reflectance. 
The index file for this collection contains observation dates,
visual magnitude,
integration time, phase angle, solar elongation, geo- and
heliocentric
distances, airmass, wavelength coverage limits, normalization
wavelength and
solar analog stars for each spectrum included.               
  


Processing                                                                


=========                                                               

The
details of the data processing are reported in Sawyer (1991) [SAWYER1991].


                                                                            


The spectra as shown in the figures of Sawyer (1991) have had the noisy red
and
blue ends trimmed, and sections affected by telluric H2O and O2 bands
edited
out.  The versions of the spectra in this archive have not had noisy
ends and
telluric bands edited out.  Comparison of these spectra with the
figures in
Sawyer (1991) will show which sections were edited out for     
publication.    

                                                             


The spectra in Sawyer (1991) have been normalized to 1.0 at 0.57 microns if
the
spectrum covers that wavelength.  Bluer spectra are normalized at 0.45
microns,
and redder spectra are normalized at 0.80 microns.  Several spectra in
this
archive do not follow this pattern and the information is lacking to
determine
what normalization and shifting have been applied to them.  For these
spectra,
the normalization wavelength is given as '9.99' in the index file.    


                                                                             



Modification History                                                      


=================                                                    

This
data set first entered the PDS archives following its successful external
peer
review on 23 March 1998.                                      
           


This data set was re-examined as part of a general review of holdings. At 


that time several upgrades and modification were made. These included:      



o  Specific target names were inserted into all labels. 
                    


o  The observational parameters in the 'sawindex.tab' file were
incorporated
into the top-level
     description field of the corresponding
label. 
         

o  The date of observations from 'sawindex.tab' was inserted
into both the
START_TIME and 
     STOP_TIME fields of the corresponding label.

             

o  Data files were renamed to indicate the asteroid number and
name, with a
sequence number 
     only when multiple spectra of a single
object are present
in this collection. 
                     
o  It was
determined that no spectrum
file contained any actual error values. The 
    
REFLECTANCE_ERROR column,
formerly present but filled with a flag value, was
thus deleted 
     from all
spectrum files and labels. 
                       

o  Two
files, '512herculina.tab' (formerly 'herculi1.tab') and
'5astraea1.tab'
(formerly 
     'astrae1.tab') contained apparently spurious
data lines at the
end of the spectrum. The                     
     
reflectance values in these
lines were printed in a different format from the
rest of the file, and 
     
the values were 2-3 orders of magnitude smaller
than the immediately preceding  

      spectral point.  These lines have been
deleted (2 lines from
'512herculina.tab' and 5 lines from 
     
'5astraea1.tab'). 
                  

o  The INSTRUMENT_HOST_NAME and
INSTRUMENT_NAME fields, previously marked
'N/A', have 
     been filled with
appropriate values. In keeping with Small
Bodies Node conventions for          

      ground-based spectra, the
instrument host is considered to be the
telescope used; the 
      instrument is
the detector. Catalog objects have
been supplied for the two hosts and          

      two instruments newly
defined. 
                                        

o  The 'sawindex.*' files
were modified to reflect the new file names. 
       

o  This catalog file was
updated to include a complete list of specific targets
and to document  
    
the other changes.


Caveats to the data user
========================

This data set is
incomplete, in that only 94 of the 164 spectra reported in
Sawyer's thesis are
included.  The spectra included so far were obtained by PDS
from Faith Vilas,
with the permission of Scott Sawyer. PDS is currently
attempting to locate a
provider for the remaining spectra.  If they are
obtained, they will be added
in an update of the data set.