An Archive of High Spectral Resolviing Power Optical Observations of Comets

The spectra of comets consist of a combination of emission lines of gaseous species that have sublimed
from the nuclear ice as the comet is heated on approach to the Sun superposed on an absorption 
spectrum arising when the dust in the coma reflects solar light.  Since most of the gaseous species
are molecules, the gas features are best viewed either at low spectral resolving power, to study a molecular
band as a whole, or at high spectral resolving power, to be able to study individual lines and line 
ratios.  We have been using the McDonald Observatory 2.7 m Harlan J. Smith Telescope with the 
Tull Coude spectrograph to observe comets with resolving power, R=λ/(Δ λ)=60,000
in the optical region from 3700Á to 1.0 microns since 1995.  These spectra are now being archived
in the Planetary Data System (PDS) Small Bodies Node (SBN) for use by the whole community and for archiving.
The archive will ultimately consist of over 80 comets.  Observations of individual comets vary from a 
single night's spectra on the optocenter to multiple nights of observations of a particular comet. Some
cometary spectra were obtained at a variety of cometocentric distances.  

For all comets in the archive, we include logs of the observations including heliocentric distance,
geocentric distance, heliocentric radial velocity, geocentric radial velocity, position in the coma, weather,
and ancillary calibration spectra.  The spectra themselves are FITS files with several extensions to
enable users to access the spectra with a variety of data tools.  The data reduction process and archiving
formats are described.

In this poster, we will indicate the structure of the archive, list the comets, indicate the progress of building
the archive and show some examples.