***** File SUMMARY.TXT                                                        
                                                                              
     The volume of ground-based Halley data archived by the nine IHW          
Disciplines is sufficiently large that, even when the Large-Scale Phenomena   
(L-SP) image arrays have been substantially subsampled, five CD-ROMs (IHW     
Volumes 19-23) are required to hold the data.  The full-resolution L-SP images
themselves take up 18 CD-ROMs (Volumes 1-18).  Not including the separate     
header (extension=.HDR) and PDS label (.LBL) files, the number of datafiles on
the so-called "mixed discs" (Volumes 19-23) is 37,844.  Due to the archiving  
of multiple observations within FITS tables by some of the Disciplines, the   
number of individual IHW observations is substantially greater than the file  
count just mentioned, however.  The table below lists the number of           
observations for each of the IHW Disciplines and sub-Disciplines:             
                                                                              
                                                                              
                                                                              
                        TABLE I                                                      
                                                                              
NUMBER OF INDIVIDUAL OBSERVATIONS FOR EACH IHW DISCIPLINE                     
                                                                              
DISCIPLINE                       Sub-DISCIPLINE  NUMBER                       
                                                                              
Astrometry                                        6475                        
                                                                              
Infrared Studies                                                              
                                 Image              95                        
                                 Photometry       2204                        
                                 Polarimetry       137                        
                                 Spectroscopy       84                        
                                                                              
Large-Scale Phenomena                             3383                        
                                                                              
Meteor Studies                                                                
                                 Radar            6962                        
                                 Visual           1624                        
                                                                              
Near Nucleus Studies                              3523                        
                                                                              
Photometry & Polarimetry                                                      
                                 Broad Band       3318                        
                                 Narrow Band     18495                        
                                 Polarimetry       752                        
                                 Stokes Parameter  164                        
                                                                              
Radio Studies                                                                 
                                 Continuum          97                        
                                 Occultation         6                        
                                 OH (molecule)    1657                        
                                 Radar               1                        
                                 Spectral Line     189                        
                                                                              
Spectroscopy & Spectrophotometry                  3368                        
                                                                              
Amateur Observations                                                          
                                 Drawing          1294                        
                                 Photography      2170                        
                                 Spectroscopy       45                        
                                 Visual          11641                        
                                                                              
                                                                              
     The actual number of files is larger than 37,844 because that count does 
not include FITS headers and PDS label files.  There are 5468 "dataless"      
observations (header and label files only), making the total data-related file
count (2*5,468 + 3*32,376) = 108,064.  Also, there are 2717 directory files   
not included in the counts.                                                   
                                                                              
     On these mixed discs (Volumes 19-23) the Halley and Halley-related data  
are located in chronological directories.  The directory names are based on   
date, specified by the year, month, UT day and hours; not all directory names 
include all these time parameters.  The naming of data directories by time    
means that the disc "time splits" can be shown by listing the first and last  
data directories for each CD-ROM Volume:                                      
                                                                              
                                                                              
         Chronological Range of "Mixed" CD-ROMs                               
                                                                              
disc          start date                  stop date                           
                                                                              
 19                 /Y1981/             /Y1985/M12/D08/                       
 20         /Y1985/M12/D09/             /Y1986/M02/D09/                       
 21         /Y1986/M02/D10/             /Y1986/M04/D13/                       
 22         /Y1986/M04/D14/             /Y1987/M04/D03/                       
 23         /Y1987/M04/D04/             /Y1989/M04/D12/                       
                                                                              
                                                                              
     Some Disciplines submitted non-Halley data, which include filter tables, 
non-comet images, flat fields, and laboratory spectra.  While many of these   
have been placed in the standard (chronologically-based) data directories,    
they have also been located in separate directories on Volume 23:             
specifically, CALIB and IR_FILTR.   Finally, Astrometry data sets for the     
apparitions of 1835 and 1909 are contained in separate directories on Volumes 
19-23, and the entire Meteor Studies Discipline dataset is contained in a     
dedicated directory on Volume 23.                                             
                                                                              
     The IHW dataset collection includes images, spectra, data tables, textual
descriptions, and indices; as indicated earlier, some "dataless" files only   
point to existing observations but do not include data.  To provide the       
Archive user the ability to conduct sophisticated searches based on time,     
IHW Discipline, or any in a wide variety of FITS keywords, several types of   
indices have been placed on these discs.  The so-called "Quick Look Indices", 
whose files are named QUIK_0nn.* (where nn=19-23), contain all the mandatory  
IHW keywords for each of the archived datafiles (including dataless); these   
indices are located in the /INDEX directory on each disc, and corrected       
versions of all five indices have been placed in the /SUMMARY/INDEX directory 
of this disc (Volume 23).                                                     
                                                                              
     Several of the Disciplines wished to index more than just the mandatory  
keyword set and constructed "Discipline-specific indices", which contain      
entries for nearly all of the FITS keywords present in the respective headers.
These indices, which bear the generic name NET*.*, are contained in the       
/INDEX/NETABLES directory of each mixed disc, as are indices containing       
parameters which may be published in the so-called "Printed Archive".  Of the 
latter (Printed Archive) indices, there is with one exception (Radio Studies  
Spectral Line index, which includes OH data) one index table per Discipline or
sub-Discipline, and contained in some of these indices are actual data.  Thus,
such indices are directly useable (without referring to the original          
datafiles), to plot light curves, extract positions, and identify meteor      
trails, for example.                                                          
                                                                              
     Production of these IHW CD-ROMs took place at the NASA/Goddard Space     
Flight Center after all the IHW data were transferred from the IHW Lead Center
at JPL to NASA/GSFC in 1990-1991.  The actual production benefited from a     
number of factors:  use of the National Space Science Data Center's (NSSDC)   
CD-ROM pre-mastering facility; a number of outside peer reviews of two        
prototype test discs; and the generation of CD-ROM Write Once discs at the    
Data Distribution Lab of the PDS at JPL.  A more complete discussion of how   
the final CD-ROMs were made is contained in the files ACKNWLDG.TXT and        
VOLINFO.TXT on this disc.                                                     
                                                                              
     Finally, there are two important printed volumes to mention.   The Comet 
Halley Archive Summary Volume edited by Sekanina and Fry (1) contains chapters
from each of the Discipline Specialist Teams describing the collection and    
processing of the data.   Other articles enumerate activites associated with  
actual production of the CD-ROMs, from which this discussion has been drawn. A
second production (2) due out is the IHW Atlas of Large-Scale Phenomena       
(Brandt, Niedner, and Rahe, 1992) that is being produced at the University of 
Colorado/Laboratory for Atmospheric and Space Physics (a comet subnode of PDS 
Small Bodies Node).  There has been no decision regarding an independent      
Printed Archive volume(s); however, now that the data have been transferred to
NASA/Goddard Space Flight Center (cf. ACKNWLDG.TXT and VOLINFO.TXT files on   
this disc), there are renewed discussions to make a version of the Printed    
Archive to complement the IHW CD-ROMs.                                        
                                                                              
1. Sekanina, Z. and Fry, L. (1991), The Comet Halley Archive Summary Volume,  
JPL 400-450, Jet Propulsion Laboratory, Pasadena, California, August, 1991.   
                                                                              
2. Brandt, J. C., Niedner, M. B., and Rahe, J. (1992), IHW Atlas of           
Large-Scale Phenomena, in press.