🌠 International Halley Watch Archive

Observations from 1985-1986, preserved for 2061

Halley's Comet Returns

Countdown: 35 Years 1 Months 26 Days 12 Hours 26 Minutes 14 Seconds

Distance to Earth: 34.128126 AU (5105495048 km)

Last updated: 2026-06-10T11:33:45.636776Z

📚 AAREADME.TXT

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AAREADME.TXT

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122 lines
***** File  AAREADME.TXT                                                      
                                                                              
                                                                              
    This compact disc (CD-ROM) contains a revised version of the comet        
Giacobini-Zinner (P/G-Z) test archive produced by the International Halley    
Watch (IHW) in cooperation with the National Space Science Data Center        
(NSSDC).  The CD-ROM also contains the comet Crommelin archive produced by the
IHW.  This disc (which has the volume id. HAL_0024) is included in the larger 
set of discs containing the comet Halley archive.  There is a mixture of data 
types on this disc that comprises 3739 (ground-based) observation files (or   
132 MByte) of P/G-Z and 680 observation files (or 39 MByte) of P/Crommelin.   
In addition, there are 25 calibration files for P/G-Z and 15 calibration files
for P/Crommelin included.                                                     
                                                                              
    The data acquired on P/Crommelin during its 1983-84 apparition were part  
of a trial run of the IHW organization.  Since this first effort by the IHW   
wasn't originally intended for inclusion on a CD-ROM, the more sophisticated  
aspects of archiving on CD-ROM (utilized for the P/G-Z and P/Halley archives) 
are not included for P/Crommelin, e.g. there are no PDS labels included, the  
FITS headers have not been detached from the data record files, the indices   
included are more primitive and fewer, etc.                                   
                                                                              
    The campaign to gather observations of the 1984-87 apparition of P/G-Z    
was begun by the IHW to support the NASA mission that sent the International  
Cometary Explorer spacecraft through the comet tail on September 11, 1985.    
(The results from most experiments on that mission have been archived by      
the NSSDC and are provided together with the spacecraft data acquired about   
comet Halley on other volumes in the complete CD-ROM set.)                    
                                                                              
    This file is the only text file that is located in the Root directory.    
A listing of the contents of the subdirectories for the CD-ROM follows:       
                                                                              
    BROWSE   - subsampled Large Scale Phenomena browse images (of P/G-Z)      
               ordered chronologically                                        
    CALIB    - supplemental data (plus headers)                               
    COMPRESS - compressed images (of P/G-Z; Previous Pixel algorithm),        
               ordered chronologically                                        
    DOCUMENT - supporting text files                                          
    EPHEM    - ephemeris data for comet                                       
    INDEX    - delimited tables for locating data                             
    SOFTWARE - supporting source and executable code                          
                                                                              
    One directory for each IHW discipline containing complete FITS files      
               in chronological order (for P/Crommelin) as well as            
               associated directories for CALIB, EPHEM, INDEX and             
               DOCUMENT                                                       
                                                                              
    Chronological directories with FITS headers, data record files, and       
               PDS labels ordered by time (for P/G-Z):                        
               * 1984 - year only                                             
               * 1985 - year, month, day, or half day (00 or 12 hours         
                        period)                                               
               * 1986 - year only                                             
               * 1987 - year only                                             
                                                                              
                                                                              
    An illustration of the subdirectory structure of this CD-ROM is given in  
the file, CDTREE.TXT, located in the DOCUMENT subdirectory.  Note that all    
explanatory files are ASCII text (.TXT) with <CR><LF> characters at the end of
each line.  To show special content some files have been given extensions as  
follows:                                                                      
                                                                              
    .APX - Appendix (text) files                                              
    .C   - C source code                                                      
    .COM - executable file (MS-DOS)                                           
    .EXE - executable file (on this disk, either VAX/VMS or MS-DOS)           
    .FOR - Fortran source code                                                
    .HHH - ASCII version of FITS header file                                  
    .IDX - delimited table files                                              
    .PRO - IDL procedure file                                                 
    .TXT - text (documentation and information) files                         
                                                                              
    The use of other file extensions (particularly in the INDEX subdirectory) 
is considered to be a common practice for dBASE III files, e.g., DBF and STR. 
Other file extensions used to document the data are described by various      
text files FITSFORM, HDRFORM, IMAGFORM, LBLFORM, SPECFORM, TABLFORM, and      
TEXTFORM.   Specialized information about other subdirectories is given in the
files listed below:                                                           
                                                                              
    BRWZINFO.TXT - discusses the browse files (of P/G-Z) and their            
                   structure                                                  
    CALINFO.TXT  - lists the groups of supplemental files (for P/G-Z)         
    COMPINFO.TXT - lists the compress files                                   
    CR_CALIB.TXT - lists the groups of supplemental files (for                
                   P/Crommelin)                                               
    CR_EPHEM.TXT - explanation of the ephemeris for P/Crommelin               
    CR_INDEX.TXT - description of how to use the table data (for              
                   P/Crommelin)                                               
    EPHEM.TXT    - explanation of the epehemeris for P/G-Z                    
    INDXINFO.TXT - description of how to use the table data (for              
                   P/G-Z)                                                     
    SOFTINFO.TXT - listing of the software information supplied               
                                                                              
    There are two special text files in the DOCUMENT directory that give an   
overview of the P/G-Z archive (GZGUIDE.TXT) and the P/Crommelin archive       
(CROMGUID.TXT), respectively.   In addition, the file CDSTRUCT.TXT is a       
listing of every file on the disc.   It has been used to construct an         
inventory file in the root directory (VOLDESC.SFD) following guidelines       
of the Consultative Committe on Space Data Systems for machine access.        
                                                                              
    For more information about the use, content, or structure of the CD-ROM,  
please contact one of the following:                                          
                                                                              
M. Aronsson              E. Grayzeck, Jr.          A. Warnock III             
IHW Lead Center          Small Bodies Node         IHW Large Scale            
                         Planetary Data System     Phenomena Network (LSPN)   
                                                                              
Mail Stop 169-237        Astronomy Program         ST Systems Corp.           
NASA/JPL                 University of Maryland    Code 681                   
4800 Oak Grove Dr.       College Park, MD 20742    NASA/Goddard SFC           
Pasadena, CA 91109                                 Greenbelt, MD 20771        
                                                                              
SPAN: JPLSC8::MIK        SPAN: CHAMP::GRAYZECK     SPAN: CHAMP::WARNOCK       
  or Internet:                 or Internet:             or Internet           
MIK@SCN6.JPL.NASA.GOV    GRAYZECK@ASTRO.UMD.EDU    WARNOCK@STARS.GSFC.NASA.GOV