***** File VOLINFO.TXT                                                        
                                                                              
                        Comet Halley Archive                                  
              User's Guide to IHW CD-ROM Volumes 25-26                        
                                                                              
                               Contents                                       
                                                                              
                                                                              
1. Background and Scope of Compact Disk                                       
2. Data Products on these Disks                                               
3. Supplemental Directories                                                   
4. File Conventions                                                           
5. PDS-FITS Comparison                                                        
6. Accessing the Disk                                                         
7. References                                                                 
                                                                              
1. BACKGROUND AND SCOPE OF COMPACT DISK                                       
                                                                              
     This compact disk (CD-ROM), and the series of disks of which it is a     
part, contains observations of comet P/Halley obtained during the 1985-1986   
apparition.  The resulting digital archive is the main product of the         
International Halley Watch (IHW), which was formed in 1981 to mount an        
international campaign to observe the comet over a long baseline in time.     
The collection of remote (mostly ground-based) data archived spans a wide     
wavelength range and is augmented (volumes 25-26) by measurements made in     
situ by the spacecraft which encountered the comet in 1986 March.  These      
spacecraft data were shipped to the Small Bodies Node (SBN) of the            
Planetary Data System which eventually archived the information.              
                                                                              
     The complete IHW digital archive is comprised of four subsets of CD-ROMs 
containing:                                                                   
                                                                              
  o Compressed Halley images from the L-SP Discipline (Volumes 1-18),         
  o Halley data from all IHW Disciplines (Volumes 19-23),                     
  o IHW "Trial Run" of comets P/Crommelin & P/Giacobini-Zinner (Volume 24),   
  o Halley and Giacobini-Zinner spacecraft data (Volumes 25-26)               
                                                                              
The total collection for Halley's Comet contains more than 40,000 independent 
files and 15 Gbytes of data.  This document is intended as a guide to volumes 
25-26.                                                                        
                                                                              
                                                                              
2. DATA PRODUCTS ON THESE DISKS                                               
                                                                              
     A large number of scientists submitted data to this archive project.   In
the case of the spacecraft data, those missions/experiments for which data    
was contributed, sometimes from differing groups, is organized below.         
                                                                              
                 Space Data Submitted for Archive                             
                                                                              
 EXPERIMENT NAME (ABBREVIATIONS)        SUBMIT INSTITUTE        CONTACT       
                                                                              
GIOTTO                                                                        
                                                                              
 DUST IMPACT DETECTOR (DID)             U CANTEBURY             S.GREEN       
 GIOTTO RADIO SCIENCE (GRE,GRS)         RADIO INST U BONN       M.BIRD        
 HALLEY MULTICOLOR CAMERA (HMC)         MPI AERONOMIE           U. KELLER     
 IMS HIGH ENERGY RANGE SPEC (IMS/HERS)  NASA/JPL                B.GOLDSTEIN   
 IMS HIGH INTENSITY SPEC (IMS/HIS)      PHYS INST U BERN        K. ALTWEGG    
 JPA MERGE (JPA/FIS, JPA/IIS)           MULLARD SPAC SCI LAB    A. COATES     
 MAGNETOMETER (MAG)                     U KOLN INST GEO METEOR  K.GLASSMEIER  
 OPTICAL PROBE EXPERIMENT (OPE)         U FLORIDA SPAC AST LAB  A.WEISENBERGER
 PARTICLE IMPACT ANALYSER (PIA)         MPI KERNPHYSIK          J.KISSEL      
                                                                              
SAKIGAKE                                                                      
                                                                              
 INTERPLANETARY MAGNETIC FIELD (IMF)    INST SPAC ASTRON SCI    K.OYAMA       
 SOLAR WIND (SOW)                       INST SPAC ASTRON SCI    K.OYAMA       
                                                                              
SUISEI                                                                        
                                                                              
 ENERGY SPECTRUM PARTICLES (ESP)        INST SPAC ASTRON SCI    K.OYAMA       
                                                                              
VEGA1                                                                         
                                                                              
 DUST PARTICLE COUNT MASS ANAL (DUCMA)  U CHICAGO               G.DENOFLO     
 INFRARED SPECTROMETER - IMAGING (IKS)  IKI                     A.DYACHKOV    
 INFRARED SPECTROMETER - SPECTRA (IKS)  IHW/IRSN                R.KNACKE      
 PLASMA ENERGY ANALYSER (PM-1,PLASMAG)  KFKI                    K.SZEGO       
 DUST MASS SPECTROMETER (PUMA)          IKI                     A.DYACHKOV    
 DUST MASS SPECTROMETER (PUMA)          MPI KERNPHYSIK          J.KISSEL      
 DUST PARTICLE PLASMA DET (SP-1)        IKI                     A.DYACHKOV    
 DUST PARTICLE DETECTOR (SP-2)          IKI                     A.DYACHKOV    
 ENERGETIC PARTICLE ANAL (TN-M,TUNDE)   IKI                     K. SZEGO      
 TELEVISION SYSTEM (TVS)                IKI                     A.DYACHKOV    
 TELEVISION SYSTEM (TVS)                KFKI                    K.SZEGO       
                                                                              
VEGA2                                                                         
                                                                              
 DUST PARTICLE COUNT MASS ANAL (DUCMA)  U CHICAGO               G.DENOFLO     
 PLASMA ENERGY ANALYSER (PM-1,PLASMAG)  KFKI                    K.SZEGO       
 DUST MASS SPECTROMETER (PUMA)          IKI                     A.DYACHKOV    
 DUST MASS SPECTROMETER (PUMA)          MPI KERNPHYSIK          J.KISSEL      
 DUST PARTICLE PLASMA DET (SP-1)        IKI                     A.DYACHKOV    
 DUST PARTICLE DETECTOR (SP-2)          IKI                     A.DYACHKOV    
 TELEVISION SYSTEM (TVS)                IKI                     A.DYACHKOV    
 TELEVISION SYSTEM (TVS)                KFKI                    K.SZEGO       
 TELEVISION SYSTEM (TVS)                INST KOSMOFORSCHUNG     D.MOHLMANN    
                                                                              
ICE                                                                           
                                                                              
 ENERGETIC PARTICLE ANISOTROPY (EPAS)   IMPERIAL COLLEGE LONDON I.RICHARDSON  
 MAGNETOMETER (MAG)                     NASA/JPL                J.WOLF        
 PLASMA WAVE ELECT FIELD (PLAWAV)       TRW                     E.GREENSTADT  
 PLASMA WAVE MAGNET FIELD (PLAWAV)      TRW                     E.GREENSTADT  
 RADIO WAVE (RADWAV)                    MEUDON                  J.-L.STEINBERG
 SOLAR WIND PLASMA (SWPLAS)             DOE/LANL                J.GOSLING     
                                                                              
In each case a unique data_set_id has been assigned to the data submission    
as indicated in the Appendix A.   A glossary of institutions listed           
above can be found in Appendix B.   In some cases, there were multiple        
submissions for the same experiment but with a different presentation         
of the data sent to the IHW-Lead Center; these data were archived by SBN      
only if the submission was determined to be a unique representation of        
the data.   In three cases (Mischa data for Vega 1 and 2, TKS and APV-N data  
for Vega 2), it was determined that the submitted data was not properly       
documented and these submissions were held back for a future addenda CD-ROM.  
                                                                              
   The spacecraft data, usually in directories by mission and experiment,     
are then arranged in a chronological order.   The subdirectory names use      
abbreviations or acronyms for mission/experiment/instrument.  In one case,    
the acronym has been shortened by dropping an intervening "dash", PM-1        
(also PLASMAG-1) and TN-M to TNM.   When multiple submissions are             
archived, the data from the original submitting institution carries a         
directory name for the experiment, while further submissions have the         
institution acronym designated in the directory.   If further editing         
or reformatting was done by others, such as the IHW or SBN, the               
filename reflects information about organization of the data such as          
for the PIA data from MPI, MODaPIA where the a stands for the class.          
In most cases, binary table data has been reformatted into ASCII              
tables.  For FITS files which contain ASCII tables, the data has been         
duplicated as a flat ASCII table as well as kept in its original form.        
For the IKS submission from IKI and IRSN, the data presented in an            
uncommon FITS form has been replaced by tabular data with corresponding       
PDS labels drawn from translating the original FITS headers.                  
                                                                              
     In the case of the TVS image data sent by IKI, the FITS header           
description was not in a convenient form, so the header was recast into       
a standard 2-dimensional representation.   The various GROUP parameters       
were translated into standard keywords as determined by comparing the         
overlapping submission of TVS data from KFKI.   Data was sent directly        
to SBN in some cases.   For the KFKI submission, unprocessed images           
outside the original encounter range for both Vega spacecraft were            
provided.   Working with the KFKI, these data were processed by SBN           
for time and noise corrections in a similar manner to the original            
submission.   FITS headers as well as the PDS labels with full time           
and processing metadata were supplied in this case.   Finally, for the        
JPA data from the Giotto mission, the data was submitted in a derived         
form that was "merged" with other relevant data.   In a specific case,        
the original file, called GIOMERGE, was provided by the IMS/HERS team         
member, M. Neugebauer.   Permission to include this form of the data          
was secured from her and other experimenters (F. Neubauer and H. Reme)        
whose MAG and RPA measurements had been included.                             
                                                                              
     More discussion of each data set is given in *.DOC files located         
with each data directory                                                      
                                                                              
                                                                              
3. SUPPLEMENTAL DIRECTORIES                                                   
                                                                              
     The volume and directory structure of this disk conform to the Level-1   
standard specified by the ISO.  This format is widely accepted and used on a  
variety of machines.  The AAREADME.TXT file in the root directory introduces  
the user to the extent of the archive and some contents of the individual     
subdirectories.                                                               
                                                                              
     There are directories (DOCUMENT and subdirectories, INDEX , SOFTWARE) on 
each disk which have additional files.  The DOCUMENT directory contains text  
files that give the background to this CD-ROM project, present a general guide
to its use, and detail previous experience with CD-ROM products.   FITS and   
PDS formats used specifically for the Halley data (with examples) is located  
in the subdirectory STDS_IHW (FITS_IHW or PDS_IHW).  The file VOLINFO.TXT you 
are reading describes the space data (it is similar to overviews such as found
on volume 23 of the Archive).  Documents in the ESA* subdirectories, written  
by the experiment Principal Investigators, contain specific information on the
instruments and preliminary data.   (These articles have been digitized by    
the PDS with permission from ESA.)   Other articles such as the SP1 and SP2   
descriptions by Balebanov 1986 were digitized by permission of the author,    
and are included in the ".DOC" files accompanying the data directory.  But    
for some references, such as IEEE Transactions on Geoscience Electronics,     
GE-16, No 3, 1978, special issue on ISEE (ICE), citations are only given.     
                                                                              
     In the INDEX directory, tables of useful information have been indexed in
the PIA and both PUMA subdirectories for the submissions from MPI.   The      
information about images from HMC and TVS (for both Vega missions) are also   
found in index tables.                                                        
                                                                              
     The SOFTWARE directory contains source code and executables for display  
of image and spectral data, reading of FITS tables, conversion of metadata,   
and manipulation of ephemeris information from tracking data.   IMDISP.EXE    
contains various utilities for manipulating visual data on image display      
devices; IMDISP was originally developed by the Planetary Data System (PDS) at
the Jet Propulsion Laboratory (JPL), and has been augmented by IHW.   Also    
provided on these disks is a "FITS Table Browser" called FTB.EXE, which was   
developed by the Astronomical Data Center (ADC) of the National Space Science 
Data Center (NSSDC).  Several other support programs for manipulating the     
metadata - FITSUTIL, FITSXTND, FITS2TXT, TXT2FITS -  are provided as UTILS.   
For the ICE spacecraft, a program (EXTRAJ.C) to extract from a "save tape"    
file parameters for the G-Z encounter is provided along with a "man" page.    
Finally, ESTEC has supplied Fortran subroutines for calculating the           
Giotto orbital parameters which are described in "GIOTTO\EPHEMRIS".  One      
of these routines, GIODAT, has been compiled and tested on a UNIX system      
and is also included separately as GIODAT.FOR file under the "EPHEMRIS"       
subdirectory along with an explanatory text.                                  
                                                                              
     On certain disks in the Archive, there is a summary directory that       
collects information about one of the four subsets.   On these same disks     
there is usually an ERRATA file that lists the latest discrepancies           
known about the Archive at the time of writing.  For the spacecraft data,     
each disk contains this information.                                          
                                                                              
                                                                              
4. FILE CONVENTIONS                                                           
                                                                              
     The convention for naming files on the IHW CD-ROMs was proposed by the   
Lead Center and NASA/Goddard Space Flight Center (GSFC) personnel to include a
unique data qualifier for the data.  Specifically, a set of subnet codes was  
established to enable identification of the IHW Discipline/subdiscipline from 
the filename itself.  A CD-ROM running number and file extension complete the 
filename for spacecraft data, e.g., HMC00001.IMG.   A list by experiment      
and listing submitting group names and letter codes is given below.   Note    
that in cases of multiple submissions, the acronym for the submitting         
group is often used in the filename, e.g., PUMA from IKI is PIKI.             
There are exceptions for certain experiments such as DUCMA, TVS for the       
VEGA missions, GRE for Giotto, and PLAWAV, RADWAV, and SWPLAS for ICE.        
                                                                              
                   IHW Space Data Filenames                                   
                                                                              
MISSION EXP     INSTR    SUBMITTER    CODE      FILENAME (OBS_ID RANG)        
                                                                              
GIOTTO  DID                           DID       DIDnnnnn 089001-089006        
                                                DSUMMARY 089007               
        GRE                           GRE       GREaaa   080001-080004        
        HMC                           HMC       HMCnnnnn 050681-033436        
        IMS      HER                  IMSHER    IMSHERnn 082001-082012        
        IMS      HIS                  IMSHIS    IMSHISnn 066001               
        JPA      FIS/IIS              JPAMERG   JPAMERGn 076001-077002        
        MAG                           MAG       MAGnnnnn 081001               
        OPE                           OPE       OPEnnnnn 083001-083005        
        PIA                           PIA       PIAMPInn 077001-077041        
                                                PIAIDX   077101               
                         SBN                    MODaPIAn                      
                                                                              
SAKIG   IMF                           IMF       IMF00001 000301               
        SOW                           SOW       SOW00001 000201               
                                                                              
SUISEI  ESP                           ESP       ESP00001 000101               
                                                                              
VEGA1   DUCMA                         D         Daaaaann 010801-010802        
        IKS              IKI          IKSIKI    IKSIKInn 010901               
                         SBN          IKS         IKSaaa                      
        PM1(PLASMAG)                  PM1       PM1annnn 010703               
        PUMA             IKI          PIKI      PIKInnnn 012001-016027        
                                                PIKIBINn 016030               
                                                MODaBINn                      
                                                MODaFITn                      
        PUMA             MPI          PMPI      PMPInnnn 011001-011017        
                         MPI                    PMPIDXnn 011101               
                         SBN                    MODaTABn                      
        SP1                                     SP1nnnnn 010704               
        SP2                                     SP2nnnnn 010705               
        TNM(TUNDE)                    TNM       TNMnnnnn 010706               
        TVS              IKI          TIKI      TIKInnnn 010001-010505        
        TVS              KFKI         T         Taaaaaaa 010101-020505        
                         KFKI/SBN     TPRE      TPREnnnn 013001-013061        
                         KFKI/SBN     TPOS      TPOSnnnn 013062-013246        
                                                                              
VEGA2   DUCMA                         D         Daaaaann 020801-020802        
        PM1(PLASMAG)                  PM1       PM1annnn 020703               
        PUMA             IKI          PIKI      PIKIBINn 021201-021202        
                         SBN                    MODaBINn                      
        PUMA             MPI          PMPI      PMPInnnn 021001-021029        
                         MPI          PMPI      PMPIDXnn 021101               
                         SBN                    MODaTABn                      
        SP1                                     SP1nnnnn 020704               
        SP2                                     SP2nnnnn 020705               
        TVS              IKI          TIKI      TIKInnnn 020101               
        TVS              KFKI         T         Taaaaaaa 020301-020604        
                         KFKI/SBN     TPRE      TPREaaaa 023001-023189        
                         KFKI/SBN     TPOS      TPOSaaaa 023190-023240        
        TVS              IKF          TIKF      TIKFnnnn 020901-020904        
                                                                              
ICE     EPAS                          EPAS      EPyymmdd 097001-097007        
                                                EPSUMMRY 097008               
        MAG                           MAG       MAyymmdd 099001-099005        
        PLAWAV   E                    E         Eddhhaaa 095120-095238        
        PLAWAV   B                    B         Bddhhaaa 095001-095119        
        RADWAV                        RW        RWyymmdd 096001               
        SWPLAS                        SW        SWyymmdd 098001-098005        
                                                                              
* The symbols in the table are defined as follows:                            
                                                                              
y - year of observation                                                       
m - month of observation                                                      
d - day of observation                                                        
h - hour of observation                                                       
a - alphanumeric code to keep track of files                                  
n - CD-ROM running number to keep track of original files                     
                                                                              
                                                                              
5. PDS-FITS COMPARISON                                                        
                                                                              
     The International Halley Watch agreed early on in the project that       
all data would be submitted from the individual groups to the Lead            
Center using the FITS format.  In the case of the spacecraft data, the        
files came in various forms, i.e., standard FITS, FITS table (ASCII) or       
for binary data the group extension,  ASCII and binary tables as FITS 2-d     
arrays, and undocumented ASCII or binary files.  The submitted FITS files,    
with contiguous headers and data, were split into separate files.  A          
PDS label was constructed to point at the data part of the file.   The        
original FITS byte stream could then be recovered by concatenating the        
appropriate header and data files.   This method was used throughout          
the first 24 volumes of the IHW archive and has been followed for the         
spacecraft data except in certain instances.   In the case of FITS            
tables, it was determined that "flat ASCII tables" with control characters    
would be most useful, so the FITS byte stream was reformatted and the         
PDS label points at that new file.   (All previous versions of the file       
are kept for consistency.)   Sometimes the FITS files used the group          
extension to incorrectly describe immages or binary tables.  In the former    
case, the FITS header was corrected and split from the data as mentioned      
above.  In the latter case, the binary data was converted to ASCII tables     
with control characters with the proper PDS label.   In another case the      
FITS 2-d array representing a binary table was converted to a simple flat     
ASCII table, while the 2-d array of ASCII values was completely reorganized   
according to the experiment "mode" and reformatted as a collection of binary  
arrays with a newly designed PDS label.   Finally, undocumented binary and    
ASCII files were submitted; in the former instance, the data has been         
reformatted into ASCII for ease of use.   In both cases, only a PDS label has 
been constructed to describe either the original or reformatted file.         
                                                                              
    These PDS labels are metadata (as headers describing data submitted to    
the archive). There has been no effort to duplicate the documentation         
contained in the full FITS headers because the PDS and FITS headers for       
a given data file differ only in the filename extension.  Instead we          
have attempted to use the power of the PDS label syntax to fully              
describe the data structures and thus gain access to software by that group.  
The references used to create the PDS labels include the following: SPIDS,    
Standards for the Preparation and Interchange of Data Sets, Martin, T.        
Z., et al, Document D-4683, V1.1, 10/3/88; Planetary Data System, Data        
Preparation Handbook, Volume 2 - Standards, V2.0, JPL D-7669, 5/3/91: and     
Planetary Data System, Standards Reference, V3.0, JPL D-7669, part 2,         
11/20/92.   The basic PDS descriptors such as SFDU_LABEL, RECORD_TYPE,        
RECORD_BYTES, and FILE_RECORDS are explained in these documents. The          
RECORD_TYPE for all data files is FIXED_LENGTH.   The PDS labels have         
been formed as fixed length (78 byte) plus an embedded CR and LF.  On         
the spacecraft volumes, labels were prepared using PDS V2.0 and V3.0; in the  
latter case, the keyword PDS_VERSION_ID (= PDS3) identifies the version.      
                                                                              
     There are three PDS objects used for the spacecraft data here: ARRAY     
(COLLECTION), IMAGE, and TABLE (& TIME_SERIES).  We construct a basic PDS     
label for each data file on the CD-ROM as shown in the table below.           
                                                                              
                                                                              
          Table Showing PDS Objects and FITS Representation                   
                                                                              
                 PDS OBJECTS/            File Ext              COMMENT        
MISSION CODE    (description)                                NAXIS= EXT       
                                                                              
GIOTTO  DID     table                .lbl .tab .hdr .tbl .fit 0,2 TABLE       
        GRE     table (time series)  .lbl .tab                1               
        HMC     image                .lbl .img .hdr           2               
        IMSHERS table                .lbl .tab                                
        IMSHIS  table                .lbl .tab .hdr .tbl .fit 0,2 TABLE       
        JPAMERG table                .lbl .tab                                
        MAG     table                .lbl .tab                                
        OPE     table                .lbl .tab .hdr .tbl .fit 0,2 TABLE       
        PIA                                    .hdr .tbl      2               
                                               .hdr .tbl      2   (INDEX)     
                array, collection    .lbl .dat                                
                                                                              
SAKIG   IMF     table                .lbl .tab                                
        SOW     table                .lbl .tab                                
                                                                              
SUISEI  ESP     table                .lbl .tab                                
                                                                              
VEGA1   D       table                .lbl .tab                                
        IKSIKI  table                .lbl .tab                2               
        IKS     table                .lbl .tab                2               
        PM1     table                .lbl .tab                                
        PIKI                                   .hdr .dat      2   (SPECTRA)   
                                                    .dat                      
                array, collection    .lbl .dat                                
                array, collection    .lbl .dat                                
        PMPI                                   .hdr .tbl      2               
                                               .hdr .tbl      2   (INDEX)     
                array, collection    .lbl .dat                                
        SP1     table                .lbl .tab                                
        SP2     table                .lbl .tab                                
        TNM     table                .lbl .tab                                
        TIKI    image                .lbl .img .hdr           2               
        T       image                .lbl .img .hdr           2               
                                                                              
VEGA2   D       table                .lbl .tab                                
        PM1     table                .lbl .tab                                
        PIKI                                        .dat                      
                array, collection    .lbl .dat                                
        PMPI                                   .hdr .tbl      2               
        PMPI                                   .hdr .tbl      2   (INDEX)     
                array, collection    .lbl .dat                                
        SP1     table                .lbl .tab                                
        SP2     table                .lbl .tab                                
        TIKI    image                .lbl .img .hdr           2               
        T       image                .lbl .img .hdr           2               
        TIKF    image                .lbl .img .hdr           2               
                                                                              
ICE     EPAS    table                .lbl .tab                                
        MAG     table                .lbl .tab                                
        E       table                .lbl .tab                                
        B       table                .lbl .tab                                
        RW      table                .lbl .tab                                
        SW      table                .lbl .tab                                
                                                                              
     The file extensions follow suggestions by the Planetary Data System      
for tabular and image data, and are listed below:                             
                                                                              
                 .DAT - other binary data                                     
                 .HDR - FITS header records                                   
                 .IMG - image data records                                    
                 .LBL - detached PDS stream format                            
                 .TAB - table data records                                    
                                                                              
In addition, the IHW used a convention to indicate a file submitted as        
a FITS ASCII table which had been split into a header (.HDR) and table        
(.TBL) part, where the latter is preserved as an ASCII byte stream in         
multiples of 2880 byte blocks.   In special cases, an ASCII table,            
which has control characters but does not follow the PDS guidelines           
for index tables, was given the extension ".IDX".   Finally, when a file      
describes a set of data (.DOC), this is distinguished from when the file      
outlines the archive or background information (given by .TXT).               
                                                                              
A. ARRAY (SPECTRUM)                                                           
                                                                              
     The ARRAY object is provided to accomodate arbitraily dimensioned arrays 
of homgeneous elements.  It was introduced as part of the PDS revision v3.0   
to describe some of the complex space craft data.   The ARRAY object has      
been used for a broader type of measurement, e.g, a mass spectrum, which      
did not fit the electromagnetic description provided by the SPECTRUM object.  
It is composed of keywords to provide a NAME and dimension (AXES) for the     
array.   Keywords AXIS_ITEMS, AXIS_NAME, AXIS_UNIT, AXIS_INTERVAL, START_AXIS 
are given in vectorial notation.   The ARRAY object normally uses the         
fundamental ELEMENT object to describe the data value.  In the IHW cases,     
it is also combined with the COLLECTION object which allows for an ordered    
grouping of heterogeneous objects.                                            
                                                                              
(     The SPECTRUM object description was refined in v2.0 by working          
closely with the PDS group to ensure definition of data groups that           
included both uniformly spaced data (as a single array) as well as            
ordered groups of observations.   From guidelines for dealing with the        
SPECTRUM data structure, we consider the spectra as tabular data              
(COLUMN, NAME, DATA_TYPE, START_BYTE, BYTES) which are binary. The            
independent variable (e.g., WAVELENGTH) is described by the keywords          
SAMPLING_PARAMETER_NAME, MINIMUM_SAMPLING_PARAMETER, SAMPLING_PARAMETER       
_INTERVAL, and SAMPLING_PARAMETER_UNIT.  There are special cases for          
Radio or IR data using Doppler VELOCITY, FREQUENCY, or FREQUENCY_OFFSET.      
                                                                              
     For remote data, an  effort was made to describe 2-dimensional           
spectra by working with PDS to establish a SPECTRAL_IMAGE_QUBE object.        
The data are reduced measurements that have the slit oriented either          
along the tail or perpendicular to the tail of the comet.   To                
capture this positional information, a vectorial notation was                 
adopted for the SPECTRAL_IMAGE_QUBE that could allow for such                 
observational selection.   In cases where the derived units were              
non-standard, a text DESCRIPTION is embedded in the label.                    
The ARRAY object can now be used to describe 2-dimensional spectra.)          
                                                                              
B. IMAGE                                                                      
                                                                              
     In the case of images, we have included a new keyword describing         
the byte ordering of the data (MSB_INTEGER) required by FITS.  In PDS,        
images (.IMG, .IMQ, .IBG) are in terms of LINES (FITS keyword NAXIS2) and     
SAMPLES (FITS keyword NAXIS1), given knowledge of the SAMPLE_BITS (FITS       
keyword BITPIX), and are easy for the split files.  The final form of the     
label for compressed images is still under active discussion.  Unlike         
previous PDS efforts with compressed images, we chose not to compress         
the header (or label) and thus have included a keyword to describe the        
type of compression (ENCODING_TYPE = "PREVIOUS PIXEL") used. The label        
for compressed images also contains information to permit software to         
skip over the data if the decoding algorithm is unknown (ITEMS,               
DATA_TYPE, and ITEM_BITS).   We use the label to indicate various subclass    
structures for the data objects.  An example of this is the DIFFERENCE        
modifier applied to IMAGE, yielding the keyword DIFFERENCE_IMAGE, which       
indicates that a processing step was applied to the original image.           
                                                                              
C. TABLE                                                                      
                                                                              
   In creating the TABLE descriptions we have found a good correspondence     
between the FITS and PDS syntax.   For tables, the value of NAXIS2= ROWS,     
TFIELDS=COLUMNS, and NAXIS1=ROW_BYTES; in both cases, the default FORMAT      
is ASCII.   We have attempted to describe the values in each column as a      
direct translation of the FITS header file; the data itself follows the FITS  
record format, i.e., ASCII characters with no delimiters and padded to        
multiples of 2880 bytes.   The FITS data structure are currently supported    
by public domain software that will be distributed with the Archive.          
In the case of simple ASCII tables, the fixed width format with a closing     
CR,LF has been preserved.                                                     
                                                                              
6. ACCESSING THE DISK                                                         
                                                                              
     These disks have been manufactured following the normal specifications   
for Compact Disk Read Only Memory (CD-ROM) as well as the logical structure   
outlined by the International Standards Organization (ISO) in the No. 9660    
document.  A basic system requirement demands that the CD-ROM reader and      
software driver support this standard.  At this writing, access to the disk   
will be through most common workstations or computers.                        
                                                                              
     The IHW CD-ROMs have been designed to allow maximum access to the data   
using existing software developed within NASA as well as user-supplied        
programs.  In particular, each data file which was originally supplied in FITS
had the headers placed in files (with extension .HDR) separate from the data  
(.DAT, .IMG, .TBL); each data file is also described by a detached PDS label. 
The headers have been separated to allow unrestricted access to the data by   
non-FITS programs.  The sizes of all header and data files have been preserved
as integer multiples of 2880 bytes (required by FITS) in order to facilitate  
the reconstruction of the original FITS bytestream by concatenating the data  
file with the appropriate header file.                                        
                                                                              
                                                                              
7. REFERENCES                                                                 
                                                                              
Martin, T., Martin, M., Braun, M., Johnson, T., Davis, R., and Mehlman, R.,   
SPIDS: Standards for the Preparation and Interchange of Data Sets, JPL        
D-4683: October 3, 1988.                                                      
                                                                              
"Information Processing -- Volume and File Structure of CD-ROM for            
Information Interchange", Reference Number ISO 9660: 1988(E), Developed in    
coordination with the National Information Standards Organization, National   
Bureau of Standards, Administration 101, Library E-106, Gaithersburg, MD.     
                                                                              
Planetary Data System. Data Preparation Workbook, Volume 2, Standards,        
V2.0, JPL D-7669, May 3, 1991.                                                
                                                                              
Planetary Data System, Standards Reference, V3.0, JPL D-7669, part 2,         
November 20, 1992.                                                            
                                                                              
                                                                              
                               Appendix A                                     
                                                                              
                        IHW Spacecraft Data_set_ids                           
                                                                              
    PDS ID                                OTHER NAMES                         
                                                                              
GIO-C-DID-3-RDR-HALLEY-V1.0               DUST-IMPACT-DETECTOR                
GIO-C-GRE-3-RDR-HALLEY-V1.0               GIOTTO-RADIO-SCIENCE                
GIO-C-HMC-3-RDR-HALLEY-V1.0               HALLEY-MULTICOLOR-CAMERA            
GIO-C-IMS-3-RDR-HERS-HALLEY-V1.0          IMS-HIGH-ENERGY-RANGE-SPEC          
GIO-C-IMS-3-RDR-HIS-HALLEY-V1.0           IMS-HIGH-INTENSITY-SPEC             
GIO-C-JPA-4-DDR-MERGE-V1.0                JPA-FIS(SWP,HAR)-IIS(4DH)-MAG-MERGE 
GIO-C-MAG-4-RDR-8SEC-HALLEY-V1.0          MAGNETOMETER-8-SECOND               
GIO-C-OPE-3-RDR-HALLEY-V1.0               OPTICAL-PROBE-EXPERIMENT            
GIO-C-PIA-3-RDR-HALLEY-V1.0               PARTICLE-IMPACT-ANALYSER            
                                                                              
SAKIG-C-IMF-3-RDR-HALLEY-V1.0             INTERPLANETARY MAGNETIC FIELD       
SAKIG-C-SOW-3-RDR-HALLEY-V1.0             SOLAR WIND                          
                                                                              
SUISEI-C-ESP-3-RDR-HALLEY-V1.0            ENERGY SPECTRUM PARTICLES           
                                                                              
VEGA1-C-DUCMA-3-RDR-HALLEY-V1.0           DUST PARTICLE COUNTER MASS ANALYSER 
VEGA1-C-IKS-2-RDR-HALLEY-V1.0             INFRARED SPECTROMETER "IMAGING" CH  
VEGA1-C-IKS-3-RDR-HALLEY-PROCESSED-V1.0   INFRARED SPECTROMETER HI RES CH     
VEGA1-C-PM1-2-RDR-HALLEY-V1.0             PLASMA ENERGY ANALYSER(PLASMAG-1)   
VEGA1-C-PUMA-2-RDR-HALLEY-V1.0            DUST MASS SPECTROMETER              
VEGA1-C-PUMA-3-RDR-HALLEY-PROCESSED-V1.0  DUST MASS SPECTROMETER - MODAL      
VEGA1-C-SP1-2-RDR-HALLEY-V1.0             DUST PARTICLE IMPACT PLASMA DETECTOR
VEGA2-C-SP2-2-RDR-HALLEY-V1.0             DUST PARTICLE IMPACT DETECTOR       
VEGA1-C-TNM-2-RDR-HALLEY-V1.0             ENERGETIC PARTICLE ANALYSER(TUNDE)  
VEGA1-C-TVS-2-RDR-HALLEY-V1.0             TELEVISION SYSTEM                   
VEGA1-C-TVS-3-RDR-HALLEY-PROCESSED-V1.0   TELEVISION SYSTEM                   
                                                                              
VEGA2-C-DUCMA-3-RDR-HALLEY-V1.0           DUST PARTICLE COUNTER MASS ANALYSER 
VEGA2-C-PM1-2-RDR-HALLEY-V1.0             PLASMA ENERGY ANALYSER(PLASMAG)     
VEGA2-C-PUMA-2-RDR-HALLEY-V1.0            DUST MASS SPECTROMETER              
VEGA2-C-PUMA-3-RDR-HALLEY-PROCESSED-V1.0  DUST MASS SPECTROMETER - MODAL      
VEGA2-C-SP1-2-RDR-HALLEY-V1.0             DUST PARTICLE IMPACT PLASMA DETECTOR
VEGA2-C-SP2-2-RDR-HALLEY-V1.0             DUST PARTICLE IMPACT DETECTOR       
VEGA2-C-TVS-2-RDR-HALLEY-V1.0             TELEVISION SYSTEM                   
VEGA2-C-TVS-3-RDR-HALLEY-PROCESSED-V1.0   TELEVISION SYSTEM                   
VEGA2-C-TVS-5-RDR-HALLEY-TRANSFORM-V1.0   TELEVISION SYSTEM                   
                                                                              
ICE-C-EPAS-3-RDR-GIACOBIN-ZIN-V1.0        ENERGETIC PARTICLE ANISOTROPY       
ICE-C-MAG-3-RDR-GIACOBIN-ZIN-V1.0         MAGNETOMETER                        
ICE-C-PLAWAV-3-RDR-ESP-GIACOBIN-ZIN-V1.0  PLASMA WAVE  ELECT FIELD            
ICE-C-PLAWAV-3-RDR-MSP-GIACOBIN-ZIN-V1.0  PLASMA WAVE MAGNET FIELD            
ICE-C-RADWAV-3-RDR-GIACOBIN-ZIN-V1.0      RADIO WAVE                          
ICE-C-SWPLAS-3-RDR-GIACOBIN-ZIN-V1.0      SOLAR WIND PLASMA                   
                                                                              
                                                                              
                                  Appendix B                                  
                                                                              
                     Acronyms for Submitting Groups                           
                                                                              
                                                                              
Institution                                Abbreviation    Country            
                                                                              
Department of Energy                           DOE          USA               
Goddard Space Flight Center                    GSFC         USA               
International Halley Watch                     IHW          USA               
Inter Kosmos Institute                         IKI          Russia            
Infrared Studies Network                       IRSN         USA               
Jet Propulsion Laboratory                      JPL          USA               
Central Research Institute for Physics         KFKI         Hungary           
Loas Alamos National Laboratory                LANL         USA               
Max Planck Institut                            MPI          Germany           
National Aeronautics and Space Administration  NASA         USA               
State University of New York                   SUNY         USA               
TRW, Incorporated                              TRW          USA