RADIO SCIENCE NETWORK                                                                                
                                                                                                                                  
                                                                                                                                  
I. INTRODUCTION                                                                                                                   
                                                                                                                                  
          Radio Astronomy is a developing new technique for the study of comets.                                                  
In some areas, such as observations of the OH radical via its 18 cm transitions,                                                  
the observational procedures and analysis are well developed.  Studies in these                                                   
areas have proved their value since they both provide new probes of important                                                     
physical processes as well as a window on physical processes which are less well                                                  
known and less amenable to study by other techniques.  In many other areas, how-                                                  
ever, the study of comets at radio wavelengths continues to be primarily an                                                       
exploratory endeavor.  In recognition of this fact, the IHW Radio Science Disci-                                                  
pline Specialist team (see Table I) feels that it is important to attempt many                                                    
different kinds of observations, since each observation tends to have some                                                        
scientific merit as an exploration. Thus, we have been careful to document and                                                    
include all data submitted to this archive by radio observers.                                                                    
                                                                                                                                  
                                                                                                                                  
Table I.  Discipline Specialist Team of the Radio Science Network                                                                 
___________________________________________________________________________                                                       
                                                                                                                                  
Team Member          Affiliation                      Responsibility                                                              
___________________________________________________________________________                                                       
                                                                                                                                  
William M. Irvine    Astronomy Program                Discipline Specialist                                                       
                     University of Massachusetts                                                                                  
                     Amherst, MA 01003                                                                                            
                     U.S.A.                                                                                                       
                                                                                                                                  
F. Peter Schloerb    Astronomy Program                Discipline Specialist                                                       
                     University of Massachusetts                                                                                  
                                                                                                                                  
Eric Gerard          Departement de Radioastronomie   Discipline Specialist                                                       
                     Observatoire de Meudon                                                                                       
                     F-92190 Meudon                                                                                               
                     France                                                                                                       
                                                                                                                                  
Ronald D. Brown      Department of Chemistry          Discipline Specialist                                                       
                     Monash University                  1981-85                                                                   
                     Clayton, Victoria 3168                                                                                       
                     Australia                                                                                                    
                                                                                                                                  
Peter D. Godfrey     Department of Chemistry          Discipline Specialist                                                       
                     Monash University                  1981-85                                                                   
                                                                                                                                  
Wayne M. Kinzel      Astronomy Program                Archive Manager                                                             
                     University of Massachusetts                                                                                  
___________________________________________________________________________                                                       
                                                                                                                                  
                                                                                                                                  
          The P/Giacobini-Zinner Archive contains data from eight observing                                                       
groups, representing a range of techniques.  Most of the observational data                                                       
come in the well developed area of 18cm OH observations.  However, other                                                          
projects, including attempts to detect continuum and spectral line emission at                                                    
other wavelengths and an attempt to observe the effects of absorption of                                                          
galactic background emission by the comet were also undertaken.  Approximately                                                    
3/4 of the groups who are known to have obtained useful data have submitted them                                                  
to the archive.  We are grateful to these observers for their contributions.                                                      
                                                                                                                                  
                                                                                                                                  
II. THE RADIO SCIENCE FITS HEADER                                                                                                 
                                                                                                                                  
          The IHW Radio Science archive is in FITS format.  The FITS files con-                                                   
sist of a header, which contains information on the observation, and data in a                                                    
format specified by the FITS header.  The header and the data are presented in                                                    
two different files to facilitate their use by a wide range of analysis soft-                                                     
ware.  Users who require FITS format files have only to concatenate the header                                                    
and the data files to make a standard FITS file for a particular observation.                                                     
                                                                                                                                  
          The FITS header is meant to give a description of the structure and                                                     
format of the FITS data records which follow it and to provide any auxiliary                                                      
information that is necessary for its interpretation.  For the Radio Science                                                      
FITS header, we have defined several FITS keywords which specify observational                                                    
parameters which are necessary to interpret the data.  A detailed description                                                     
of the complete Radio Science FITS header is provided in Sec. III.  In general,                                                   
the Radio Science Network has tried to conform to standards which are commonly                                                    
used in FITS and adopted by the IHW.  The characteristics of the observation are                                                  
described by assigning values to the keywords which are described in Sec. III.                                                    
Special keywords have been selected to provide information vital to the data                                                      
interpretation, such as specification of the observing frequency or telescope                                                     
parameters.  At another level, under the FITS HISTORY keywords, we describe how                                                   
the data were obtained, including calibration and orbital tracking information.                                                   
The organization of the parameters into these groups is admittedly somewhat                                                       
arbitrary and has been made primarily to limit the number of new FITS keywords                                                    
defined by our Network.                                                                                                           
                                                                                                                                  
          In an exploratory program, like the Radio Science Network, it is to be                                                  
expected that on many occasions attempts to detect the comet will fail.  These                                                    
nondetections are best described by an appropriate upper limit rather than                                                        
through presentation of a spectrum or image.  In recognition of this fact, the                                                    
IHW permits FITS files to be created without any data records; the limit is then                                                  
listed in the FITS HISTORY section of the Radio Science header.  The FITS files                                                   
of this type have the NAXIS keyword set equal to 0 and the DAT-TYPE keyword set                                                   
equal to the character string 'NODATA  '.                                                                                         
                                                                                                                                  
          Where possible, even when actual data exist, we have attempted to                                                       
describe them by presenting the results of a model fit to the data.  For exam-                                                    
ple, in spectral line work a line is often described in terms of its peak inten-                                                  
sity, the velocity of the peak, the line width, the integrated area under the                                                     
line, and the mean velocity of the emission.  We have provided these values in                                                    
FITS HISTORY keywords by fitting a gaussian line shape model to the data.                                                         
                                                                                                                                  
                                                                                                                                  
III. RADIO SCIENCE FITS HEADER DESCRIPTION                                                                                        
                                                                                                                                  
          Information provided in the FITS header has been organized into seven                                                   
keyword blocks.                                                                                                                   
                                                                                                                                  
A. Keyword Block I: Basic FITS Keywords                                                                                           
                                                                                                                                  
          This block is required of FITS tapes.  The details are presented in                                                     
Table II below.                                                                                                                   
                                                                                                                                  
                                                                                                                                  
Table II. Keyword Block I                                                                                                         
________________________________________________________________________________                                                  
                                                                                                                                  
Keyword  Type  Description                                                                                                        
________________________________________________________________________________                                                  
                                                                                                                                  
SIMPLE    L    Conformity to basic FITS standards                                                                                 
BITPIX    I    Bits per pixel in data record                                                                                      
NAXIS     I    Number of axes in data record; if NAXIS = 0 then no data record                                                    
NAXIS1    I    Number of pixels in row along first axis                                                                           
NAXISn    I    Number of pixels along n-th axis in image                                                                          
________________________________________________________________________________                                                  
                                                                                                                                  
                                                                                                                                  
B. Keyword Block II: International Halley Watch Keywords                                                                          
                                                                                                                                  
          These keywords are agreed upon for use by the IHW and are listed in                                                     
Table III.                                                                                                                        
                                                                                                                                  
                                                                                                                                  
Table III. Keyword Block II                                                                                                       
________________________________________________________________________________                                                  
                                                                                                                                  
Keyword  Type  Description                                                                                                        
________________________________________________________________________________                                                  
                                                                                                                                  
OBJECT    C    Name of the object: 'P/GIACOBINI-ZINNER'                                                                           
FILE-NUM  I    6NNNNV - Unique, sequential number to identify files sent to IHW                                                   
                    Lead Center.  Format description:                                                                             
                    6 = denotes Radio Science Network                                                                             
                 NNNN = Unique 4 digit ID number assigned to each observation                                                     
                    V = Version Number (has no effect on usage)                                                                   
DATE-OBS  C    'DD/MM/YY' - UT date of middle of observation                                                                      
                    if observations made during several intervals, then these                                                     
                    intervals will be specified in the HISTORY fields described                                                   
                    below                                                                                                         
TIME-OBS  R    UT Time of middle of observation expressed in decimal days                                                         
DATE-REL  C    'DD/MM/YY' - Date when observations may be publicly released                                                       
DISCIPLN  C    'RADIO STUDIES' - The Network identification                                                                       
LONG-OBS  C    'DDD/MM/SS' - East longitude of observatory (0-360 degrees)                                                        
LAT--OBS  C    'sDD/MM/SS' - Latitude of observatory                                                                              
SYSTEM    C    '6OOOCCTT' - System code formatted:                                                                                
                    6 = Radio Studies Network                                                                                     
                  OOO = IAU number for observatory                                                                                
                        (OOO=500 for radio observatories--no IAU numbers exist)                                                   
                   CC = Identifies country according to LSPN Code                                                                 
                   TT = Identifies radio telescope                                                                                
OBSERVER  C    Name of Observer                                                                                                   
                    Format : 'LASTNAME,I'            - 1 author                                                                   
                             'LASTNAME,I/NEXTNAME,J' - 2 authors                                                                  
                             'LASTNAME,I/ET AL.'     - >2 authors                                                                 
                    For more than 2 observers, the names of all additional                                                        
                    observers are given in special ADD. OBS. comments                                                             
SUBMITTR  C    Name of submitter of data                                                                                          
SPEC-EVT  L    Flag for special events as designated by Discipline Specialist                                                     
DAT-FORM  C    Describes format of FITS data records                                                                              
               'NODATA  ' - No FITS data records written                                                                          
               'STANDARD' - Data records conform to FITS standard                                                                 
               'ASCII   ' - Data records are to be interpreted as logical                                                         
                            records of 80 ASCII characters (not FITS standard)                                                    
               'HARDCOPY' - Data submitted as hardcopy                                                                            
________________________________________________________________________________                                                  
                                                                                                                                  
                                                                                                                                  
C. Keyword Block III: Radio Science Keywords                                                                                      
                                                                                                                                  
          These keywords are to be directly read by computers in the normal                                                       
manner of FITS header keywords.  Some attempt has been made to choose keyword                                                     
names that are already in use by the astronomical community.  These keywords                                                      
are used to describe information that is vital to the interpretation of the                                                       
data or potentially useful for searches of the data base (Table IV).                                                              
                                                                                                                                  
                                                                                                                                  
Table IV. Keyword Block III                                                                                                       
________________________________________________________________________________                                                  
                                                                                                                                  
Keyword  Type  Description                                                                                                        
________________________________________________________________________________                                                  
                                                                                                                                  
DIS-CODE  C    'TFESEWEABENC' Describes the parameters of the                                                                     
                              telescope/instrument                                                                                
               T : Telescope Type                                                                                                 
                    S = Single Antenna                                                                                            
                    I = Interferometer                                                                                            
                    U = Unknown/Unclassified                                                                                      
               FE: Frequency (Center Frequency or Rest Frequency)                                                                 
                    FE=> Frequency = F X 10**(E) MHz                                                                              
                    00=  Unknown                                                                                                  
               SE: Spectral Resolution                                                                                            
                    SE=> Spectral Resolution = S X 10**(E) Hz                                                                     
                    00=  Unknown                                                                                                  
               WE: Bandwidth                                                                                                      
                    WE=> Bandwidth = W X 10**(E) Hz                                                                               
                    00=  Unknown                                                                                                  
               A : Beam Description                                                                                               
                    C = Circular                                                                                                  
                    E = Ellipitical                                                                                               
                    O = Other                                                                                                     
                    U = Unknown                                                                                                   
               BE: Beam Size (Geometric Mean)                                                                                     
                    BE=> Beam Size = B X 10**(E) arcsec                                                                           
                    00= Unknown                                                                                                   
               N : Noise Estimate                                                                                                 
                    N => RMS Noise = 10**(N) microJansky/Beam                                                                     
                    0 = Unknown                                                                                                   
               C : Information provided by observer to Discipline Specialist is                                                   
                    complete                                                                                                      
                    T = TRUE                                                                                                      
                    F = FALSE                                                                                                     
DAT-TYPE  C    'NNSTHP' Indicates the data format within Header and Data Records                                                  
               NN: Subnetwork                                                                                                     
                    OH= OH Subnetwork                                                                                             
                         Spectral line observations of 18-cm OH                                                                   
                    SL= Spectral Line Subnetwork                                                                                  
                         Spectral line observations (other than 18-cm OH)                                                         
                    CN= Continuum Subnetwork                                                                                      
                         Broadband continuum observations                                                                         
                    OC= Occultation Subnetwork                                                                                    
                         Observation of occultation events                                                                        
                    RD= Radar Subnetwork                                                                                          
                         Active experiments                                                                                       
               S : Search/Detection Status                                                                                        
                    S = Search - implies nondetection (< 3 sigma)                                                                 
                    D = Detection - implies detection (> 3 sigma)                                                                 
                    M = Marginal - implies marginal detection (approx. 3 sigma)                                                   
               T : Type of Data in FITS Data Records                                                                              
                    N = No FITS Data Records                                                                                      
                    S = Spectrum           => Intensity vs Frequency                                                              
                    C = Continuum Scan     => Intensity vs Space                                                                  
                    T = Time Series        => Intensity vs Time                                                                   
                    I = Image              => Spatial - Spatial Image                                                             
                    D = Dynamic Spectrum   => Frequency - Time Image                                                              
                    F = SV Image           => Frequency - Spatial Image                                                           
                    V = Visibility Function Data                                                                                  
               H : Summary of Data in Header?                                                                                     
                    T = Summary of Data exists in Header History Section                                                          
                    F = No Summary of Data in Header History Section                                                              
               P : Polarization Status                                                                                            
                    I = Intensity Data Only                                                                                       
                    P = Polarization Data Format Used                                                                             
OBSVTORY  C    Abbreviation for Observatory.                                                                                      
TELESCOP  C    Telescope Identifier - usually gives aperture size in meters                                                       
LOCATION  C    Location of Observatory as given in American Ephemeris                                                             
INSTRUME  C    'FRONT/BACK' - describes "frontend" and "backend" of receiver                                                      
               FRONT: Receiver Front End                                                                                          
                    MASER = Maser Amplifier                                                                                       
                    FET   = Field Effect Transistor Amplifier                                                                     
                    PARA  = Parametric Amplifier                                                                                  
                    MIXER = Mixer                                                                                                 
                    SPEC  = Special Front End                                                                                     
                    UNK   = Unknown Front End                                                                                     
               BACK  : Receiver Back End                                                                                          
                    FB    = Filterbank                                                                                            
                    SEFB  = Filterbank with Spectrum Expander                                                                     
                    AC    = Autocorrelator                                                                                        
                    CONT  = Broadband Continuum Receiver                                                                          
                    SPEC  = Special Back End                                                                                      
                    AOS   = Acousto-Optical Spectrometer                                                                          
                    UNK   = Unknown Back End                                                                                      
CENTFREQ  R    Center Frequency of Observed Bandwidth (Hz)                                                                        
BANDWIDT  R    Total Bandwidth (Hz)                                                                                               
BEAMSIZE  R    Geometric Mean of Major and Minor Axes of Elliptical Gaussian                                                      
               Beam (deg)                                                                                                         
BEAMELON  R    Ratio of Major Beam Axis to Minor Beam Axis                                                                        
BEAMROTA  R    Position Angle of Major Beam Axis (deg)                                                                            
BEAMEFF   R    Beam Efficiency - Fraction of power recieved that is in the                                                        
               Gaussian Main Beam (BEAMEFF = 0.0 if unknown or unspecified)                                                       
MOLECULE  C    Chemical Formula for Molecule (Follows Convention of NBS                                                           
               Interstellar line list)                                                                                            
TRANSITN  C    Quantum Numbers for Transition (Follows Convention of NBS                                                          
               Interstellar line list)                                                                                            
RESTFREQ  R    Rest Frequency of line used by observer (Hz)                                                                       
RES-SPEC  R    Spectral Resolution (Hz) - This is intended to be the true spec-                                                   
                 tral resolution of the spectrometer, NOT the channel spacing                                                     
EQUINOX   R    Equinox of RA-DEC information presented in this file                                                               
RAOFF     R    Pointing Offset in RA direction DELTA(RA)*COS(DEC) (deg)                                                           
DECOFF    R    Pointing Offset in Dec direction DELTA(DEC) (deg)                                                                  
DATE-BEG  C    'DD/MM/YY' - UT date on which observations began                                                                   
DATE-END  C    'DD/MM/YY' - UT date on which observations ended                                                                   
________________________________________________________________________________                                                  
                                                                                                                                  
                                                                                                                                  
D. Keyword Block IV: Special Keywords for Printed Archive                                                                         
                                                                                                                                  
          This group of COMMENT lines give additional information to be used in                                                   
the production of the IHW printed archive.                                                                                        
                                                                                                                                  
          The ADD. OBS. comment gives the names of the full observing team in                                                     
the case that more than two observers carried out the observations.  More than                                                    
one ADD. OBS. comment may be used to specify teams with many members or long                                                      
names.  The format of the ADD. OBS. comment is:                                                                                   
                                                                                                                                  
COMMENT   ADD. OBS. NAME,I/NAME2,I/NAME3,I                                                                                        
                                                                                                                                  
          The NOTE comment provides information that is to be printed as a foot-                                                  
note in the printed archive in the following format:                                                                              
                                                                                                                                  
COMMENT   NOTE      THIS IS A TEST                                                                                                
                                                                                                                                  
E. Keyword Block V: Radio Science Data History Section                                                                            
                                                                                                                                  
          This block of FITS HISTORY keywords is provided to give additional                                                      
information about the observation, such as descriptions of calibration methods                                                    
and sources, details about observing procedures, and comments by the observer                                                     
and the IHW Discipline Specialist.  Another important use of the HISTORY lines                                                    
is to provide a summary of the data obtained, or in the case of FITS files with                                                   
no data records, the actual data values reported by the observer.  The general                                                    
format of the HISTORY lines is:                                                                                                   
                                                                                                                                  
column                                                                                                                            
1        11        21                                                                                                             
HISTORY   SUBKEY__  VALUES....                                                                                                    
                                                                                                                                  
where values is a list of values associated with this subkey.  In most cases,                                                     
the value lists are in a fixed format in order to simplify their use.                                                             
                                                                                                                                  
          E.1. DATA SUMMARY SECTION                                                                                               
                                                                                                                                  
          In order to transmit upper limits or a summary of the data that                                                         
would be appropriate for tabular presentation in the printed archive, we                                                          
utilize one of the following HISTORY keyword formats.  Such summaries of the                                                      
data will always be contained in the first part of the HISTORY keyword section;                                                   
the presences of such a summary shall be indicated in the DAT-TYPE keyword                                                        
discussed above.  In the case where FITS data records accompany the header,                                                       
USERS OF THE ARCHIVE ARE CAUTIONED THAT THE SUMMARY VALUES ARE ONLY MEANT TO                                                      
DESCRIBE AND CHARACTERIZE THE DATA ... NOT TO REPLACE THEM.                                                                       
                                                                                                                                  
          All summary lines follow the same general form:                                                                         
                                                                                                                                  
HISTORY   SUBKEY    ################  'UNITS   '                                                                                  
                                                                                                                                  
where the # field is a right justified floating point number.                                                                     
                                                                                                                                  
          Format for Upper Limits:                                                                                                
                                                                                                                                  
COMMENT             *SUMMARY OF DATA - UPPER LIMIT                                                                                
HISTORY   LIMIT                  0.5  'JY/BEAM '                                                                                  
                                                                                                                                  
Upper Limits in the Radio Science Net are always given as 3 standard deviation                                                    
upper limits.                                                                                                                     
                                                                                                                                  
          Format for Spectral Lines:                                                                                              
                                                                                                                                  
COMMENT             *SUMMARY OF DATA - SPECTRAL LINE                                                                              
HISTORY   LINEPEAK               0.5  'JY/BEAM '                                                                                  
HISTORY   ERR-PEAK               0.1  'JY/BEAM '                                                                                  
HISTORY   LINE-VEL              10.0  'M/SEC   '                                                                                  
HISTORY   ERR--VEL             200.2  'M/SEC   '                                                                                  
HISTORY   LINE-WID            2532.0  'M/SEC   '                                                                                  
HISTORY   ERR--WID             130.2  'M/SEC   '                                                                                  
HISTORY   LINEAREA            1243.1  'JY/B*M/S'                                                                                  
HISTORY   ERR-AREA             143.6  'JY/B*M/S'                                                                                  
HISTORY   LINEMEAN              32.1  'M/SEC   '                                                                                  
HISTORY   ERR-MEAN              10.2  'M/SEC   '                                                                                  
                                                                                                                                  
The spectral line summary values LINEPEAK, LINE-VEL, and LINE-WID are determined                                                  
from gaussian fits to the line profiles.  If one or more parameters were fixed                                                    
in a fit to the data, the assumed values are listed with no errors.  Spectral                                                     
lines with hyperfine structure (e.g., HCN) are fitted on the assumption that all                                                  
hyperfine components have their nominal intensity ratios.                                                                         
                                                                                                                                  
          Format for Continuum Observations:                                                                                      
                                                                                                                                  
COMMENT             *SUMMARY OF DATA - CONTINUUM                                                                                  
HISTORY   CONTFLUX               0.5  'JY/BEAM '                                                                                  
HISTORY   ERR-FLUX               0.1  'JY/BEAM '                                                                                  
                                                                                                                                  
          E.2. OBSERVING WINDOWS SECTION                                                                                          
                                                                                                                                  
          Since many radio observations take place over several days, we include                                                  
the precise observing windows in the HISTORY section according to the format:                                                     
                                                                                                                                  
COMMENT             *OBSERVING WINDOW SPECIFICATION                                                                               
HISTORY   N-WINDOW                 #                                                                                              
HISTORY   WINDOW    'DD/MM/YY' #######     'DD/MM/YY' #######                                                                     
...       ...       ...                                                                                                           
...       ...       ...                                                                                                           
...       ...       ...                                                                                                           
HISTORY   WINDOW    'DD/MM/YY' #######     'DD/MM/YY' #######                                                                     
                                                                                                                                  
where N-WINDOW gives the total number of windows for observation and subsequent                                                   
window lines give the date and time (in decimals as in TIME-OBS) of beginning                                                     
and end of the observing window.  The time fields are right justified floating                                                    
point numbers.                                                                                                                    
                                                                                                                                  
          E.3. ORBITAL ELEMENTS SECTION                                                                                           
                                                                                                                                  
          Radio observers track the comet "blind" and it is important to know                                                     
the precise position on the sky that they were tracking. We include a provision                                                   
in the HISTORY section to specify the two-body elements and observatory position                                                  
data used to produce the topocentric ephemeris for tracking.                                                                      
                                                                                                                                  
COMMENT             *ORBITAL ELEMENT SPECIFICATION                                                                                
HISTORY   ORBELEM                  T       - T if orbital elements are present                                                    
HISTORY   LONGEAST      243.11046715       - east longitude of observatory (deg)                                                  
HISTORY   RHO--COS      0.8159113419       - radius*cos(lat) for observatory                                                      
                                             (units of Earth equatorial radius)                                                   
HISTORY   RHO--SIN      0.5765085118       - radius*sin(lat) for observatory                                                      
                                             (units of Earth equatorial radius)                                                   
HISTORY   ET-UT             53.18439       - Ephemeris Time - UT correction (s)                                                   
HISTORY   JD           2446471.16128       - Time of Perihelion passage (ET)                                                      
HISTORY   Q                0.5870959       - Perihelion Distance (AU)                                                             
HISTORY   E                0.9672671       - Eccentricity                                                                         
HISTORY   SOMEGQ           111.85336       - Arg. of Perihelion (deg)                                                             
HISTORY   LOMEGA            58.15313       - Long. of Ascending Node (deg)                                                        
HISTORY   I                162.23779       - Inclination (deg)                                                                    
                                                                                                                                  
          E.4. ANTENNA TRACKING SECTION                                                                                           
                                                                                                                                  
          This HISTORY keyword specifies the antenna rms pointing errors.                                                         
                                                                                                                                  
COMMENT             *RMS POINTING ERROR OF TELESCOPE                                                                              
HISTORY   POINTERR  ################ 'UNITS   '                                                                                   
                                                                                                                                  
          E.5. CALIBRATION SECTION                                                                                                
                                                                                                                                  
          This group of keywords provides information about details of the ca-                                                    
libration process.                                                                                                                
                                                                                                                                  
COMMENT             *CALIBRATION METHOD INFORMATION                                                                               
HISTORY   CALMETH   'DESCRIPTION OF CAL METHOD'                                                                                   
                                                                                                                                  
If calibration method is unknown, then no line appears. Current possible values                                                   
are 'CHOPPER WHEEL', 'NOISE TUBE', 'STANDARDS'                                                                                    
                                                                                                                                  
COMMENT             *CALIBRATION STANDARD INFORMATION                                                                             
HISTORY   CALSRCE   'SOURCE NAME'    ########## 'UNITS   '                                                                        
                                                                                                                                  
Source (or sources) used to provide principal calibration.  The # field is a                                                      
right justified floating point number. For planets as the calibrators, the                                                        
assumed brightness temperature is given; otherwise, the calibrator flux density                                                   
is given in Jansky.  There may be more than one CALSRCE HISTORY line.                                                             
                                                                                                                                  
COMMENT             *SYSTEM TEMPERATURE ETC.                                                                                      
HISTORY   TSYSTEM   ############### '_SB     '                                                                                    
HISTORY   TRCVR     ############### '_SB     '                                                                                    
                                                                                                                                  
Total system temperature (TSYSTEM) and noise temperature of the reciver alone                                                     
(TRCVR).  '_SB     ' allows single side band measurement ('SSB     ') or double                                                   
sideband measurement ('DSB     ') to be indicated.  The # field is a right                                                        
justified floating point number.                                                                                                  
                                                                                                                                  
HISTORY   TAUZENTH  ###############                                                                                               
                                                                                                                                  
Atmospheric opacity at zenith.  The # field is a right justified floating point                                                   
number.                                                                                                                           
                                                                                                                                  
          E.6. OBSERVER'S COMMENT SECTION                                                                                         
                                                                                                                                  
          This block of HISTORY lines contains any extra comments about condi-                                                    
tions, data quality, etc. that are sent to the Discipline Specialist by the                                                       
observer.  There are generally fewer than eight such comment lines.                                                               
                                                                                                                                  
COMMENT             *OBSERVER COMMENTS                                                                                            
HISTORY   OBSCOMM   ROOM TO REPORT OBSERVERS COMMENTS                                                                             
HISTORY   OBSCOMM   ...                                                                                                           
HISTORY   OBSCOMM   ...                                                                                                           
HISTORY   OBSCOMM   MORE ROOM FOR OBSERVER COMMENTS                                                                               
                                                                                                                                  
          E.7. DISCIPLINE SPECIALIST'S COMMENT SECTION                                                                            
                                                                                                                                  
          Comments by the Discipline Specialist team on this observation.  There                                                  
are generally fewer than eight such comment lines.                                                                                
                                                                                                                                  
COMMENT             *DISCIPLINE SPECIALIST COMMENTS                                                                               
HISTORY   DSCOMM    ROOM TO REPORT DISCIPLINE SPECIALIST COMMENTS                                                                 
HISTORY   DSCOMM    ...                                                                                                           
HISTORY   DSCOMM    ...                                                                                                           
HISTORY   DSCOMM    MORE ROOM FOR DISCIPLINE SPECIALIST COMMENTS                                                                  
                                                                                                                                  
                                                                                                                                  
F. Keyword Block VI: Standard FITS Keywords                                                                                       
                                                                                                                                  
          These keywords are used to describe the FITS data records.  They are                                                    
all standard and summarized in Table V.                                                                                           
                                                                                                                                  
                                                                                                                                  
Table V.  Keyword Block VI                                                                                                        
________________________________________________________________________________                                                  
                                                                                                                                  
Keyword  Type  Description                                                                                                        
________________________________________________________________________________                                                  
                                                                                                                                  
BSCALE    R    Scale Factor  Data = tape * BSCALE + BZERO                                                                         
BZERO     R    Zero Value                                                                                                         
BUNIT     C    Units of Data                                                                                                      
               'JY/BEAM ' - for line and continuum data                                                                           
BLANK     I    Value for out-of-range data                                                                                        
CRVALn    R    Value of physical coordinate of nth axis at the reference pixel                                                    
CRPIXn    R    Array location of reference pixel for nth axis                                                                     
CDELTn    R    increment in physical coordinate along nth axis                                                                    
CTYPEn    C    Type of physical coordinate                                                                                        
               'VELO-COM' - frequency coordinate for line work in m/s                                                             
                            defined to be velocity relative to the comet                                                          
               'VELO-GEO' - velocity defined relative to center of Earth                                                          
               'CIRCULAR POLARIZATION' - axis used to define different states of                                                  
                                       circular polarization: -1 = LHC; -2 = RHC                                                  
               'LINEAR POLARIZATION' - axis used to define linear polarization                                                    
                                     position angle                                                                               
               'RAOFF   ' - spatial coordinate for maps (deg)                                                                     
               'DECOFF  ' - spatial coordinate for maps (deg)                                                                     
                                                                                                                                  
CROTAn    R    Rotation angle of physical coordinate axis n                                                                       
________________________________________________________________________________                                                  
                                                                                                                                  
                                                                                                                                  
G. Keyword Block VII: End Statement                                                                                               
                                                                                                                                  
          This keyword is required by FITS to terminate the header:                                                               
                                                                                                                                  
END                                                                                                                               
                                                                                                                                  
                                                                                                                                  
IV. THE RADIO SCIENCE NETWORK INDEX TO THE CD-ROMS                                                                                
                                                                                                                                  
          The IHW provides various indices to help users of the archive find                                                      
the data that they want.  For the Radio Science Network, there are two indices                                                    
provided by the project which users will find useful: the quick look index and                                                    
the printed archive (see Sec. V for description), both of which contain                                                           
information on all observations in the archive.  The Radio Science Network                                                        
provides a third, discipline specific, index which contains much more detailed                                                    
information about the radio observations than the others.  In selecting the                                                       
information to be included in the Radio Science Index, we have attempted to                                                       
include all relevant data from the FITS headers, within limitations imposed by                                                    
standards set by the Halley Watch.  The detailed format of the Radio Science                                                      
index is given in Table VI.                                                                                                       
                                                                                                                                  
                                                                                                                                  
Table VI.  IHW Radio Science Network Index Format                                                                                 
________________________________________________________________________________                                                  
                                                                                                                                  
Field    Keyword            Type  Format    Notes                                                                                 
________________________________________________________________________________                                                  
                                                                                                                                  
   1     OBJECT              C    A20                                                                                             
   2     FILE-NUM            N    I6                                                                                              
   3     DATE-OBS            D    A8        IHW Date Format                                                                       
   4     TIME-OBS            N    F6.5                                                                                            
   5     LONG-OBS            C    A9                                                                                              
   6     LAT-OBS             C    A9                                                                                              
   7     SYSTEM              C    A8                                                                                              
   8     OBSERVER            C    A24                                                                                             
   9     COMMENT  ADD. OBS.  C    A60       May exclude some observers                                                            
  10     SUBMITTR            C    A24                                                                                             
  11     SPEC-EVT            L    L1                                                                                              
  12     DAT-FORM            C    A8                                                                                              
  13     DIS-CODE            C    A12                                                                                             
  14     DAT-TYPE            C    A6                                                                                              
  15     OBSVTORY            C    A10                                                                                             
  16     TELESCOP            C    A10                                                                                             
  17     LOCATION            C    A30                                                                                             
  18     INSTRUME            C    A20                                                                                             
  19     CENTFREQ            N    F11.4     in MHz                                                                                
  20     BANDWIDT            N    F11.4     in MHz                                                                                
  21     BEAMSIZE            N    F6.4                                                                                            
  22     BEAMELON            N    F6.3                                                                                            
  23     BEAMROTA            N    F6.1                                                                                            
  24     BEAMEFF             N    F6.3                                                                                            
  25     EQUINOX             N    F8.3                                                                                            
  26     RAOFF               N    F7.4                                                                                            
  27     DECOFF              N    F7.4                                                                                            
  28     MOLECULE            C    A10                                                                                             
  29     TRANSITN            C    A20                                                                                             
  30     RESTFREQ            N    F11.4     in MHz                                                                                
  31     RES-SPEC            N    F11.4     in kHz                                                                                
  32     HISTORY  LIMIT      N    F11.4     in Jy/Beam                                                                            
  33     HISTORY  LINEPEAK   N    F11.4     in Jy/Beam                                                                            
  34     HISTORY  ERR-PEAK   N    F11.4     in Jy/Beam                                                                            
  35     HISTORY  LINE-VEL   N    F11.4     in m/s                                                                                
  36     HISTORY  ERR--VEL   N    F11.4     in m/s                                                                                
  37     HISTORY  LINE-WID   N    F11.4     in m/s                                                                                
  38     HISTORY  ERR--WID   N    F11.4     in m/s                                                                                
  39     HISTORY  LINEAREA   N    F11.4     in Jy/Beam * m/s                                                                      
  40     HISTORY  ERR-AREA   N    F11.4     in Jy/Beam * m/s                                                                      
  41     HISTORY  LINEMEAN   N    F11.4     in m/s                                                                                
  42     HISTORY  ERR-MEAN   N    F11.4     in m/s                                                                                
  43     HISTORY  CONTFLUX   N    F11.4     in Jy/Beam                                                                            
  44     HISTORY  ERR-FLUX   N    F11.4     in Jy/Beam                                                                            
  45     DATE-BEG            D    A8        Date Format                                                                           
  46     DATE-END            D    A8        Date Format                                                                           
  47     HISTORY  NWINDOW    N    I1                                                                                              
  48     HISTORY  WINDOW (1) D    A8        Start Date of 1st Window (Date Fmt)                                                   
  49     HISTORY  WINDOW (1) N    F5.3      Start Time of 1st Window                                                              
  50     HISTORY  WINDOW (N) D    A8        End Date of Last Window (Date Fmt)                                                    
  51     HISTORY  WINDOW (N) N    F5.3      End Time of Last Window                                                               
  52     HISTORY  POINTERR   N    F10.2     in arcsec                                                                             
  53     HISTORY  CALMETH    C    A20                                                                                             
  54     HISTORY  CALSRCE (1)C    A15       Name of Cal Source 1                                                                  
  55     HISTORY  CALSRCE (1)N    F10.3     Value of Cal Source 1                                                                 
  56     HISTORY  CALSRCE (1)C    A15       Units of Cal Source 1                                                                 
  57     HISTORY  CALSRCE (2)C    A15       Name of Cal Source 2                                                                  
  58     HISTORY  CALSRCE (2)N    F10.3     Value of Cal Source 2                                                                 
  59     HISTORY  CALSRCE (2)C    A15       Units of Cal Source 2                                                                 
  60     HISTORY  TSYSTEM    N    F7.1      Value Only                                                                            
  61     HISTORY  TRCVR      N    F7.1      Value Only                                                                            
  62     HISTORY  TAUZENTH   N    F4.2                                                                                            
  63     BITPIX              N    I2                                                                                              
  64     NAXIS               N    I1                                                                                              
  65     BSCALE              N    F15.9                                                                                           
  66     BZERO               N    F10.4                                                                                           
  67     BUNIT               C    A15                                                                                             
  68     BLANK               N    I6                                                                                              
  69     DATAMAX             N    F10.4                                                                                           
  70     DATAMIN             N    F10.4                                                                                           
  71     NAXIS1              N    I4                                                                                              
  72     CDELT1              C    A15                                                                                             
  73     CRPIX1              C    A15                                                                                             
  74     CRVAL1              C    A15                                                                                             
  75     CTYPE1              C    A25                                                                                             
  76     NAXIS2              N    I4                                                                                              
  77     CDELT2              C    A15                                                                                             
  78     CRPIX2              C    A15                                                                                             
  79     CRVAL2              C    A15                                                                                             
  80     CTYPE2              C    A25                                                                                             
   :        :                :     :                                                                                              
  96     NAXIS6              N    I4                                                                                              
  97     CDELT6              C    A15                                                                                             
  98     CRPIX6              C    A15                                                                                             
  99     CRVAL6              C    A15                                                                                             
 100     CTYPE6              C    A25                                                                                             
 101     Path:Volume         C    A8        Path to file on CD-ROM                                                                
 102     Path:Year SubDirect C    A5        Ditto                                                                                 
 103     Path:Month SubDir.  C    A3        Ditto                                                                                 
 104     Path:Day SubDirect  C    A3        Ditto                                                                                 
 105     Path:Hour SubDirect C    A3        Ditto                                                                                 
 106     Filename            C    A8        Filename without extension                                                            
_______________________________________________________________________________                                                   
                                                                                                                                  
                                                                                                                                  
V. THE RADIO SCIENCE NETWORK PRINTED ARCHIVE                                                                                      
                                                                                                                                  
          In addition to the FITS presentation of the Radio Science Network                                                       
data, an additional format is available in the printed archive.  This format                                                      
provides most of the information that is necessary to make use of the data, as                                                    
well as the "data summary" information included in the FITS headers, such as                                                      
the line peak intensity and width for spectral line observations.  The format                                                     
of the printed archive for the Radio Science Network is shown below.                                                              
                                                                                                                                  
A. Printed Format I: OH Subnetwork and Spectral Line Subnetwork                                                                   
                                                                                                                                  
          Since the OH Subnetwork and the Spectral Line Subnetwork contain the                                                    
same data type, it is most economical to print both subnetworks together in the                                                   
same subsection of the Radio Science part of the archive.  Detailed description                                                   
of this format is in Table VII.                                                                                                   
                                                                                                                                  
                                                                                                                                  
Table VII.  Printed Format I                                                                                                      
________________________________________________________________________________                                                  
                                                                                                                                  
Col.  FITS                        Field        Field         Notes                                                                
      Keywords                    Format       Header                                                                             
________________________________________________________________________________                                                  
                                                                                                                                  
  1   DATE-OBS,TIME-OBS          DD.TTTTT      Date(UT)                                                                           
 10   FILE-NUM                      I6         RSN#                                                                               
 17   MOLECULE                      A5         Mol                                                                                
 23   DAT-TYPE (4th Character)      A1         Typ           Denotes Subnetwork                                                   
 25   RESTFREQ (MHz)                I6         Freq                                                                               
 32   RES-SPEC (kHz)                I4         Resol                                                                              
 37   HISTORY  TSYSTEM (K)          I5         Tsys                                                                               
 43   BEAMEFF (per cent)            I2         BE                                                                                 
 46   BEAMSIZE (arcsec)             I4         HP                                                                                 
 51   DIS-CODE (8th Character)      A1         BS            Denotes Beam Shape                                                   
 53   Radial Offset of              I4         Offset rho                                                                         
      Beam from Nucleus (arcsec)                                                                                                  
 58   Position Angle of             I3         Offset theta                                                                       
      Radial Offset (degrees)                                                                                                     
                                                                                                                                  
      For Limits:                                                                                                                 
                                                                                                                                  
 62   A "<" symbol                  A1                                                                                            
 63   HISTORY  LIMIT (Jy/Beam)      F6.1       Line Peak     if value>10Jy/Beam                                                   
                                 or F6.3                     if value<10Jy/Beam                                                   
 80   A "-" symbol                  A1         Width                                                                              
 91   A "-" symbol                  A1         Velocity                                                                           
                                                                                                                                  
      For Detections:                                                                                                             
                                                                                                                                  
 63   HISTORY  LINEPEAK (Jy/Beam)   F6.1                     if value>10Jy/Beam                                                   
                                 or F6.3                     if value<10Jy/Beam                                                   
 69   A "plus or minus" symbol      A1         Line Peak                                                                          
 70   HISTORY ERR-PEAK (Jy/Beam)    F5.1                     if value>10Jy/Beam                                                   
                                 or F5.3                     if value<10Jy/Beam                                                   
 76   HISTORY  LINE-WID (km/sec)    F4.2                                                                                          
 80   A "plus or minus" symbol      A1         Width                                                                              
 81   HISTORY  ERR--WID (km/sec)    F4.2                                                                                          
 86   HISTORY  LINE-VEL (km/sec)    F5.2                                                                                          
 91   A "plus or minus" symbol      A1         Velocity                                                                           
 92   HISTORY  ERR--VEL (km/sec)    F4.2                                                                                          
                                                                                                                                  
      For All:                                                                                                                    
                                                                                                                                  
 97   SYSTEM                        A8         System                                                                             
106   OBSERVER                      A21        Observer(s)                                                                        
128   COMMENT NOTE                  A5         Notes                                                                              
________________________________________________________________________________                                                  
                                                                                                                                  
                                                                                                                                  
B. Printed Format II: Continuum Subnetwork                                                                                        
                                                                                                                                  
          The data in the continuum subnetwork are fundamentally different from                                                   
the spectral line data in the previous section.  Thus they require a separate                                                     
format, listed in Table VIII.                                                                                                     
                                                                                                                                  
                                                                                                                                  
Table VIII.  Printed Format II                                                                                                    
________________________________________________________________________________                                                  
                                                                                                                                  
Col.  FITS                        Field        Field         Notes                                                                
      Keywords                    Format       Header                                                                             
________________________________________________________________________________                                                  
                                                                                                                                  
  1   DATE-OBS,TIME-OBS          DD.TTTTT      Date(UT)                                                                           
 11   FILE-NUM                      I6         RSN#                                                                               
 19   DAT-TYPE (4th Character)      A1         Typ           Denotes Subnetwork                                                   
 22   CENTFREQ (MHz)                I6         Freq                                                                               
 30   BANDWIDT (MHz)                I6         BW                                                                                 
 38   HISTORY  TSYSTEM              I5         Tsys                                                                               
 45   BEAMEFF (per cent)            I2         BE                                                                                 
 49   BEAMSIZE (arcsec)             I4         HP                                                                                 
 55   DIS-CODE (8th Character)      A1         BS            Denotes Beam Shape                                                   
 58   Radial Offset of              I4         Offset rho                                                                         
      Beam from Nucleus (arcsec)                                                                                                  
 63   Position Angle of             I3         Offset theta                                                                       
      Radial Offset (degrees)                                                                                                     
                                                                                                                                  
      For Limits:                                                                                                                 
                                                                                                                                  
 68   A "<" Symbol                  A1                                                                                            
 69   HISTORY  LIMIT (Jy/Beam)      F6.1       Flux Density  if value>10Jy/Beam                                                   
                                 or F6.3                     if value<10Jy/Beam                                                   
                                                                                                                                  
      For Detections:                                                                                                             
                                                                                                                                  
 69   HISTORY CONTFLUX (Jy/Beam)    F6.1                     if value>10Jy/Beam                                                   
                                 or F6.3                     if value<10Jy/Beam                                                   
 75   A "plus or minus" symbol      A1         Flux Density                                                                       
 76   HISTORY ERR-FLUX (Jy/Beam)    F5.1                     if value>10Jy/Beam                                                   
                                 or F5.3                     if value<10Jy/Beam                                                   
                                                                                                                                  
      For All:                                                                                                                    
                                                                                                                                  
 83   SYSTEM                        A8         System                                                                             
 93   OBSERVER                      A21        Observer(s)                                                                        
115   COMMENT NOTE                  A5         Notes                                                                              
________________________________________________________________________________                                                  
                                                                                                                                  
                                                                                                                                  
C. Printed Format III: Occultation Subnetwork                                                                                     
                                                                                                                                  
          The data in the occultation subnetwork also require a separate format;                                                  
they are listed in Table IX.                                                                                                      
                                                                                                                                  
                                                                                                                                  
Table IX.  Printed Format III                                                                                                     
________________________________________________________________________________                                                  
                                                                                                                                  
Col.  FITS                        Field        Field         Notes                                                                
      Keywords                    Format       Header                                                                             
________________________________________________________________________________                                                  
                                                                                                                                  
   1  DATE-OBS,TIME-OBS          DD.TTTTT      Date(UT)                                                                           
  11  FILE-NUM                      I6         RSN#                                                                               
  19  SOURCE                        A12        Source                                                                             
  34  DAT-TYPE (4th Character)      A1         Typ           Denotes Subnetwork                                                   
  37  CENTFREQ (MHz)                I6         Freq                                                                               
  45  SYSTEM                        A8         System                                                                             
  55  OBSERVER                      A21        Observer(s)                                                                        
  77  COMMENT NOTE                  A5         Notes                                                                              
________________________________________________________________________________                                                  
                                                                                                                                  
                                                                                                                                  
VI. UNITS IN THE RADIO SCIENCE ARCHIVE                                                                                            
                                                                                                                                  
          We have attempted to use a fixed set of standard units for the values                                                   
given in the IHW archive.  These units are given in Table X.  Where these units                                                   
are not used, as in the printed archive, the index tables, or in certain values                                                   
in the HISTORY section of the FITS headers, the change of units is explicitly                                                     
mentioned.                                                                                                                        
                                                                                                                                  
          The adoption of the flux density unit, Jansky per Beam (Jy/Beam),                                                       
deserves an additional comment.  This unit is well defined: the signal is                                                         
described in terms of the flux density of a point source which would produce the                                                  
same signal as that observed from the comet.  The explicit use of "per Beam" in                                                   
the unit acknowledges that the coma is possibly resolved by the beam to an                                                        
unknown extent.  Some observatories, such as the VLA, have naturally already                                                      
adopted this choice of units since they use celestial point sources to calibrate                                                  
the instrument.  All continuum observations also use Janskys to express their                                                     
results regardless of how the data are actually internally calibrated.  Thus,                                                     
in both of these cases, the Jansky is the obvious choice of unit.  For spectral                                                   
line work on large single antennas, however, results are typically expressed in                                                   
"antenna temperature" since they are calibrated by comparing the observed                                                         
signal to a calibration signal of known noise temperature.  In recent years,                                                      
this unit has become rather confusing as a result of efforts to convert a                                                         
relatively well defined observed quantity into a more physically meaningful                                                       
unit which gives an approximation to the true brightness temperature of the                                                       
source.  Thus, various forms of "corrected" antenna temperature are in use at                                                     
different observatories, and it is often not clear which corrections have been                                                    
made to the data.  We therefore favor a system in which the calibration is                                                        
achieved by direct comparison of the cometary signal to celestial sources of                                                      
known flux density, and the natural unit for such a comparison is the unit of                                                     
flux density, the Jansky.  Thus, all observations in the archive have been                                                        
converted to these units using data provided by the observers.                                                                    
                                                                                                                                  
                                                                                                                                  
Table X.  Radio Science Units                                                                                                     
_____________________________                                                                                                     
                                                                                                                                  
Angle                 Degrees                                                                                                     
Length                 Meters                                                                                                     
Time                  Seconds                                                                                                     
Frequency               Hertz                                                                                                     
Velocity        Meters/Second                                                                                                     
Flux Density     Jansky/Beam*                                                                                                     
_____________________________                                                                                                     
                                                                                                                                  
* 1 Jansky = 1.0*10(-26) Watts                                                                                                    
  per square meter per Hertz                                                                                                      
                                                                                                                                  
                                                                                                                                  
VII. CALIBRATION                                                                                                                  
                                                                                                                                  
          Although we have converted the data in the archive to a common unit                                                     
of flux density, we have made no attempt to recalibrate data to a common flux                                                     
density scale.  The calibration scale for radio astronomy is well established at                                                  
centimeter wavelengths, and in general, well known standard sources were used by                                                  
the network observers.  For wavelengths shorter than about 1 centimeter, how-                                                     
ever, the calibration becomes less precise as atmospheric attenuation becomes                                                     
significant in the observations. In most cases, comparisons to celestial sources                                                  
are more indirect and observers rely on absolute calibration schemes as their                                                     
primary method.  Ultimately, though, even these techniques use known sources,                                                     
such as the planets, to calibrate the system, and we have attempted to archive                                                    
information about these calibration sources with each observation.                                                                
                                                                                                                                  
          Calibration information that is supplied to us by the observer is                                                       
given in the HISTORY section of the FITS header.  The HISTORY  CALMETH keyword                                                    
provides an ASCII string with a brief description of the calibration method                                                       
used.  Three methods are commonly used: (1) STANDARDS indicates that the data                                                     
were calibrated through direct comparison to standard sources; (2) NOISE TUBE                                                     
indicates that the data were primarily calibrated by injecting power from a                                                       
noise source into the receiver; (3) CHOPPER WHEEL indicates that the "chopper                                                     
wheel" method was used.  This latter method uses the comparison of the noise                                                      
power from an ambient temperature load to that produced by the sky emission to                                                    
make an estimate of the optical depth of the atmosphere, and it is commonly                                                       
used at millimeter wavelengths.                                                                                                   
                                                                                                                                  
          Even in the cases of NOISE TUBE and CHOPPER WHEEL calibration, where                                                    
celestial sources are not initially used to calibrate the data, the final                                                         
calibration is generally made with celestial sources.  Whenever a standard                                                        
source is used for this purpose, its name and assumed flux density are given in                                                   
the HISTORY  CALSRCE keywords.  More than one of these keywords may exist in                                                      
the header if more than one calibration source is used.  For planetary sources,                                                   
the assumed brightness temperature is given rather than the flux density since                                                    
planetary flux densities vary with distance to the object.  Finally, the system                                                   
temperature (defined to be the total system noise temperature including                                                           
receiver noise and atmospheric and ground pickup) and the receiver temperature                                                    
(defined to be the noise temperature of the receiver alone) are given in the                                                      
HISTORY  TSYSTEM and HISTORY  TRCVR keywords; the atmospheric opacity at zenith                                                   
is given in the HISTORY  TAUZENTH keyword where appropriate.                                                                      
                                                                                                                                  
                                                                                                                                  
ACKNOWLEDGEMENTS                                                                                                                  
                                                                                                                                  
          Several people who are not members of the Discipline Specialist Team                                                    
(listed in Table I) have also made substantial contributions to the success of                                                    
the Radio Science Network of the International Halley Watch.  First of all, we                                                    
wish to acknowledge the contributions from the observers who have submitted data                                                  
to the archive, since if it were not for their interest and assistance, then                                                      
there would be no archive.  We also appreciate those who attempted to observe                                                     
comet P/Giacobini-Zinner even if they did not get useful data.  In many cases,                                                    
these early attempts paid off in our later studies of comet Halley.  The Disci-                                                   
pline Specialists at the University of Massachusetts were aided in their effort                                                   
by a number of collaborators during the course of our involvement with the IHW.                                                   
We gratefully acknowledge the efforts of R. Bassett, M. Claussen, C. Clemens,                                                     
R. Molloy, G. Moriarty-Schieven, D. Swade, and L. Tacconi-Garman, who have                                                        
provided assistance to the project at various times throughout its duration.