Data Set Overview : 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.

Review : The data set underwent external peer review on March 23, 1998.   Limitations :  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.