Data Set Overview
=================
 
         McDonald Observatory Faint Comet Survey Gas Data
 
This study presents spectral data from 152 observations of 17 comets
obtained using an Intensified Dissector Scanner spectrograph at the
McDonald Observatory.
 
A full description of these data and the reduction process, along with
Haser model production rates can be found in Cochran et al. (1992)
[COCHRANETAL1992].
 
 
Parameters
==========
All essential parameters including fluxes, aperture positions and size,
comet heliocentric and geocentric positions and heliocentric radial
velocity are provided in this PDS submission.  The fluorescence
efficiencies used for the column density calculations can be found in
Cochran et al. (1992) [COCHRANETAL1992], along with additional Haser
Model parameters and estimated production rates. Measures of the
cometary continuum and gas-to-dust ratios are available in Storrs
et al. (1992) [STORRSETAL1992].
 
Processing
==========
The processing carried out on the McDonald Observatory Faint Comet Survey
are described elsewhere [COCHRANETAL1992; STORRSETAL1992; COCHRAN1987].
 
Using standard star measurements, the raw data counts were converted to
flux units.  The separate sky spectrum was then subtracted from the
object spectra, weighting by the strength of the 5577 A night sky line
to account for different exposure times.  A color corrected solar spectrum
was then removed and the various bands were integrated in order to measure
the emission band intensities.  The fluorescence efficiencies given below
[COCHRANETAL1992] were then used to convert to column densities.
 
Molecule           Constant
CN                 f(dR/dt) heliocentric
C3                 12.42
CH                 12.98
C2 (delta NU = 1)  12.62
C2 (delta NU = 0)  12.35
NH2 (0,10,0)       13.73
 
Data
====
 
1) fluxcdmc.tab: cometocentric aperture positions and fluxes and column
                 densities for all dates.
3) parammc.tab: Contains the  parameters associated with the observations.
 
In calculating the flux and column densities for the six molecular species
the following bandpasses (from Table I of COCHRANETAL1992) were used:
 
molecule         Bandpass (A)
CN (delta NU = 0) 3830-3905
C3                3975-4150
CH                4280-4340
C2 (delta NU = 1) 4460-4770
C2 (delta NU = 0) 4860-5185
NH2 (0,10,0)      5675-5760
 
 
Coverage
========
 
The following 17 comets are included in this data set:
 
                                      Principal      Obsolete
    Number, Type and Name            Designation   Designation(s)
    ------------------------------   -----------   --------------
     49P/Arend-Rigaux                  1951 C2     1984k
       C/Austin                        1982 M1     1982g
       C/Austin                        1984 N1     1984i
       C/Bradfield                     1987 P1     1987s
     67P/Churyumov-Gerasimenko         1969 R1     1982f
     26P/Grigg-Skjellerup              1922 K1     1982a, 1986m
     68P/Klemola                       1965 U1     1987i
     22P/Kopff                         1906 Q1     1982k, 1988k
       C/Levy-Rudenko                  1984 V1     1984t
     25P/Neujmin 1                     1913 R2     1984c
       C/Nishikawa-Takamizawa-Tago     1987 B1     1987c
     24P/Schaumasse                    1911 X1     1984m
       C/Sorrells                      1986 V1     1986n
     64P/Swift-Gehrels                 1889 W1     1981j
      9P/Tempel 1                      1867 G1     1982j
     10P/Tempel 2                      1873 N1     1982d  1987g
     62P/Tsuchinshan 1                 1965 A1     1984p
 
The obsolete designations have been removed from the data files and
replaced with the IAU principal designations.
 
 
Ancillary Data
==============
A complementary dataset regarding the continuum spectral measurements
and an ad hoc measure of the cometary dust emission, A(theta)*f*rho
[AHEARNETAL1984], can be found in STORRSETAL1992.
 
 
Media/Format
============
This dataset is released in the form of ASCII files which may be
stored on disk or other magnetic medium and which may be
distributed by ftp, email, real-time access by remote login, or by
whatever means is most convenient.

Review
======
The MOFCS has been reviewed internally by Anita Cochran prior to release
to the planetary community. An external PDS peer review was held in late
September 1998.