PDS_VERSION_ID = PDS3                                                         
                                                                              
RECORD_TYPE  = FIXED_LENGTH                                                   
RECORD_BYTES = 80                                                             
FILE_RECORDS = 18785                                                          
                                                                              
^TABLE       = "JPAMERG1.TAB"                                                 
                                                                              
DATA_SET_ID  = "GIO-C-JPA-4-DDR-HALLEY-MERGE-V1.0"                            
TARGET_NAME  = HALLEY                                                         
START_TIME   = 1986-03-12T06:09:34.460                                        
DESCRIPTION  = "This table contains results from the Implanted Ion Sensor     
                (IIS) 4DH mode and the Fast Ion Sensor SW and HAR modes       
                of the Three-Dimensional Particle Analyser (JPA) experiment   
                on the GIOTTO space craft for the mission to comet            
P/Halley.  The results of the Fast Ion Sensor (FIS - inbound) and IIS         
(outbound) have been merged with magnetometer results in this file. Values    
are given for protons.                                                        
                                                                              
JPA FIS data are from two sources:                                            
                                                                              
 - up to March 13, 19:24:55 SCET, data are from the solar wind mode at 8      
   seconds time resolution.  The moments are derived from data in a           
   45 x 45 degree field of view, centered on the nominal solar wind           
   direction.  There is continuous converage in energy and angle.  The        
   peak remains within this reduced field of view.                            
                                                                              
 - March 13, 19:24:55 to 22:38:17 SCET, data are from the HAR mode at 24      
   second time resolution.  This mode has an angular field of view            
   accepting ions from all directions except a 20 deg cone in the ram         
   direction.  Energy-angle coverage is not contiguous in this mode so        
   an assumption is made to boost the counts in each bin to make the          
   distribution appear contiguous.  The peak of the solar wind flux           
   alternates between the last two 26 deg bins during this period.            
   Moments are calculated for the regions of space sampled by the             
   detector, i.e. up to the 20 deg ram cone, with no assumption to increase   
   the range beyond this.   After 19:24:55 on the inblound pass when the      
   HAR mode data are used, the values given should be divided by 3.2 to       
   take account of the bin sizes for HAR (see Coates, et al. (1990).          
                                                                              
The following assumptions hold: FIS is an electrostatic analyser and so       
cannot distinguish mass - except in the solar wind mode where the protons     
and alpha particles are cold enough that they separate in energy/charge; in   
HAR mode the moment is over the full FIS energy range so includes anything    
(all protons).                                                                
                                                                              
JPA IIS data is from the 4DH mode.   In this mode, the Time of Flight         
measurement is combined with the energy level information provided by         
the IIS to separate mass groups, e.g., 0-1.7 amu/q (presumably protons).      
The moments are derived from data collected during one spacecraft spin,       
i.e., 128 s, at each of 32 energy levels to obtain a complete distribution.   
Pickup protons are included in the numbers but this is only a small effect.   
The IIS temperature quoted on the outbound pass should be treated as a        
relative value; by intercalibration with FIS on the inbound pass the          
temperature in K is given by multiplying the numbers by a factor of 1000.     
                                                                              
The 'JPAMERGE' file includes both FIS and IIS data. The JPA data up           
to 22:38:17 are from FIS given every 8 s.   (At this time the sampling        
changes to every 64 s; only magnetometer values are listed in this interval.) 
The JPA data starts again at approx 0104 on March 14 (MJD 13221 or            
day 73), and is from the IIS 4DH mode. This data has a time resolution        
of 128 seconds - in the merge file it is combined with 64s                    
magnetometer data, which is why there are two MAG points for every            
JPA data repeated twice here.   (The last 16 lines are again only             
magnetometer values.)    The end time of the data is 02:46:28 on March 15.    
                                                                              
There are some differences in the timing and values shown in the JPAMERGE     
file for the MAG data as shown in the following table:                        
                                                                              
           Mag values      JPA values      Times    Data gap filling          
JPAMERG1       =               =             0          None                  
JPAMERG2     Not =             =           -4.46s      -999.9                 
MAG00001       =              N/A          +0.36s      -999.9                 
                                                                              
The timing differences in the JPA data occur for 3 reasons:                   
   (1) Use of beginning of bin or middle of bin                               
   (2) Internal buffering of 0.5 sec in JPA                                   
   (3) Crossing time of the solar wind across the FIS field of view,          
         which occurs 0.25 sec after the beginning of a bin                   
The correct JPA times for a middle of bin could be retrieved by adding        
3.75s to the times in JPAMERG1.                                               
                                                                              
In the existing files:                                                        
   - MAG data are averages at the middle of the time bin given in all         
        cases, which explains the difference in values (not noticeable        
        on a plot) in JPAMERG2. However the reason for the time               
        difference between JPAMERG1 and MAG00001 is unclear, it may be        
        an attempt to correct for the actual time of the solar wind           
        entering the FIS field of view.                                       
   - JPA data are beginning of bin in file JPAMERG1. In JPAMERG2              
        attempts were made to make the data middle of bin but                 
        unfortunately 3.75s should have been added to the data as             
        mentioned above. This mistake could have occurred during              
        addition of data at other institutes.                                 
                                                                              
Therefore, treat times as accurate to +/- 4s.                                 
                                                                              
As data from both experiments were not available for the entire time          
interval, missing datasets have been replaced by zeroes."                     
                                                                              
                                                                              
                                                                              
RECORD_FORMAT = "F14.8, F9.3, F8.3, F8.3, F6.2, F9.1, 3(F8.3)"                
                                                                              
                                                                              
OBJECT        = TABLE                                                         
  NAME        = "JPAMERG1_TABLE"                                              
                                                                              
  INTERCHANGE_FORMAT = ASCII                                                  
  COLUMNS     = 9                                                             
  ROW_BYTES   = 80                                                            
  ROWS        = 18785                                                         
  DESCRIPTION = "This table contains velocity and magnetic field vectors      
                 with related data, tagged with an observation time.          
                 Coordinates are centered on the comet.   A definition        
                 of such an HSE coordinate system (right handed) follows:     
                 x-axis towards sun, y-axis parallel to the ecliptic plane    
                 and z-axis perpendicular to the ecliptic towards the N       
                 celestial pole."                                             
                                                                              
  OBJECT        = COLUMN                                                      
    NAME        = SC_EVENT_TIME                                               
    BYTES       = 14                                                          
    DATA_TYPE   = ASCII_REAL                                                  
    START_BYTE  = 1                                                           
    FORMAT      = "F14.8"                                                     
    UNIT        = "MJD"                                                       
    DESCRIPTION = "Spacecraft event time expressed as modified Julian date,   
                   where 13220 is 13 March 1986."                             
  END_OBJECT                                                                  
                                                                              
  OBJECT        = COLUMN                                                      
    NAME        = PROTON_VX                                                   
    BYTES       = 9                                                           
    DATA_TYPE   = ASCII_REAL                                                  
    START_BYTE  = 15                                                          
    FORMAT      = "F9.3"                                                      
    UNIT        = "KM/S"                                                      
    DESCRIPTION = "Proton X velocity component, HSE coordinate system"        
  END_OBJECT                                                                  
                                                                              
  OBJECT        = COLUMN                                                      
    NAME        = PROTON_VY                                                   
    BYTES       = 8                                                           
    DATA_TYPE   = ASCII_REAL                                                  
    START_BYTE  = 24                                                          
    FORMAT      = "F8.3"                                                      
    UNIT        = "KM/S"                                                      
    DESCRIPTION = "Proton Y velocity component, HSE coordinate system"        
  END_OBJECT                                                                  
                                                                              
  OBJECT        = COLUMN                                                      
    NAME        = PROTON_VZ                                                   
    BYTES       = 8                                                           
    DATA_TYPE   = ASCII_REAL                                                  
    START_BYTE  = 32                                                          
    UNIT        = "KM/S"                                                      
    FORMAT      = "F8.3"                                                      
    DESCRIPTION = "Proton Z velocity component, HSE coordinate system"        
  END_OBJECT                                                                  
                                                                              
  OBJECT        = COLUMN                                                      
    NAME        = PROTON_NUMBER_DENSITY                                       
    BYTES       = 6                                                           
    DATA_TYPE   = ASCII_REAL                                                  
    START_BYTE  = 40                                                          
    FORMAT      = "F6.2"                                                      
    UNIT        = "CM**-3"                                                    
    DESCRIPTION = "Number density of protons"                                 
  END_OBJECT                                                                  
                                                                              
  OBJECT        = COLUMN                                                      
    NAME        = PROTON_TEMPERATURE                                          
    BYTES       = 9                                                           
    DATA_TYPE   = ASCII_REAL                                                  
    START_BYTE  = 46                                                          
    FORMAT      = "F9.1"                                                      
    UNIT        = "KELVIN"                                                    
    DESCRIPTION = "Temperature of the protons, in Kelvin"                     
  END_OBJECT                                                                  
                                                                              
  OBJECT        = COLUMN                                                      
    NAME        = B_X                                                         
    BYTES       = 8                                                           
    DATA_TYPE   = ASCII_REAL                                                  
    START_BYTE  = 55                                                          
    FORMAT      = "F8.3"                                                      
    UNIT        = "NANOTESLA"                                                 
    DESCRIPTION = "X component of magnetic field, HSE coordinate system"      
  END_OBJECT                                                                  
                                                                              
  OBJECT        = COLUMN                                                      
    NAME        = B_Y                                                         
    BYTES       = 8                                                           
    DATA_TYPE   = ASCII_REAL                                                  
    START_BYTE  = 63                                                          
    FORMAT      = "F8.3"                                                      
    UNIT        = "NANOTESLA"                                                 
    DESCRIPTION = "Y component of magnetic field, HSE coordinate system"      
  END_OBJECT                                                                  
                                                                              
  OBJECT        = COLUMN                                                      
    NAME        = B_Z                                                         
    BYTES       = 8                                                           
    DATA_TYPE   = ASCII_REAL                                                  
    START_BYTE  = 71                                                          
    FORMAT      = "F8.3"                                                      
    UNIT        = "NANOTESLA"                                                 
    DESCRIPTION = "Z component of magnetic field, HSE coordinate system"      
  END_OBJECT                                                                  
                                                                              
END_OBJECT    = TABLE  /* JPAMERG1_TABLE */                                   
END