File: p10mgd.txt                              
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    PIONEER-10 INTERPLANETARY SOLAR WIND PLASMA AND MAGNETIC FIELD DATA

Data Set Date Coverage: 1972-03-03 to 1995-12-31

NSSDC Data Set ID: SM-41F (NSSDC Heliospheric CD-ROM)

Experiments: Pioneer 10 Helium Vector Magnetometer (HVM) 
             Pioneer 10 Plasma Science (PLS) Experiment 

Principal Investigators:

   HVM - Dr. Edward J. Smith, NASA Jet Propulsion Laboratory, Pasadena, CA
   PLS - Dr. Aaron Barnes, NASA Ames Research Center, Moffett Field, CA
 
Data Set Description:
           
  The  main science objectives for the PIONEER interplanetary mission are as 
  follows:
               
  - search for the heliospheric boundary with interstellar space;
              
  - study the large-scale structure of the solar wind plasma and
    interplanetary magnetic field within the heliosphere;
              
  - investigate propagation of solar and galactic energetic particles
    in the heliosphere;
               
  - measure the radial gradient, spectra, and nuclear composition of the
    anomalous cosmic rays from the solar wind termination shock;
                
  - study acceleration of energetic particles by solar flare shocks and
    corotating interaction regions within the heliosphere.
                 
  PI of magnetic field data: Dr. Edward J. Smith, NASA JPL.
  PI of plasma data: Dr. Aaron Barnes, Ames Research Center, NASA;
              plasma data were provided by Dr. P. Gazis, ARC.
  
   For the hourly resolution records,                              
  the  PIONEER_10  directory  contains  hourly  averages  of  parameters for
  the interplanetary  magnetic field (1972-Mar-3 (63) - 1975-Nov-17 (321)), 
  solar wind plasma (1972-Apr-18 (109) - 1995-Sep-07 (250)), and 
  spacecraft trajectory  coordinates (1972-Mar-3  (63) - 1995-Dec-31 (365)). 
               
  Time Coverage of merged files: March 3, 1972 - December 31, 1995

Data Set Format:

              
  Pioneer-10 data have been reprocessed to ensure a uniformity of 
  content and coordinate systems relative to data from other deep-
  space missions:

  - All spacecraft trajectory data were transformed to a Heliographic
    Inertial (HGI) coordinate system.

  - merging of trajectory coordinates, magnetic field data, and plasma data
    files into a single annual file P10_YR.DAT, where YR is the year;
            
  - Data gaps were filled with dummy numbers for the missing hours or entire
    days to make all files of equal length.  The character '9' is used to
    fill all fields for missing data according to their format, e.g.
    ' 9999.9' for a field with the FORTRAN format F7.1. Note that format F7.1
    below really means (1X,F6.1),etc.
              
For the daily resolution data (one file), simple averages were taken over
the hourly values.  The format is identical to that for the hour averages
However, the "hour" field has 0 as a value.and the "Magnitude of Average
Vector" field is the simple average of the 24 hourly values of this parameter.

              Format Description:

 WORD  ASCII     MEANING                         UNITS/COMMENTS
                                                                        
 1     I4       YEAR                                    1980......... 
 2     I4       DECIMAL DAY                              January 1 =Day 1  
 3     I3       HOUR                                     (0,1,......23)   
 4     F7.2     Spacecraft Heliocentric             astronomical units
                   Distance

 5     F7.1     Heliographic Inertial Latitude        degrees, +/- 90
                   of the spacecraft position
                   
 6     F7.1     Heliographic Inertial Longitude       degrees, 0-360
                   of the spacecraft position
 7    F9.4     BR RTN coordinate system                 NANOTESLAS
 8    F9.4     BT RTN coordinate system                 NANOTESLAS
 9    F9.4     BN RTN coordinate system                 NANOTESLAS
 10   F9.4     Scalar B                                 NANOTESLAS 
 11   F7.1      Proton Bulk flow speed, RTN                       km/s
 12   F7.1      THETA-elevation angle                   Degrees        
               of flow velocity vector
               (RTN-cordinate system)
 13   F7.1      PHI- azimuth angle of                   Degrees
               flow velocity vector.
               (RTN-coordinate system) 
 14   F9.4      Proton density                          [n/cc]
 15   F9.0      Proton Temperature                      degrees, K   
             

                      DESCRIPTION OF COORDINATE SYSTEMS
                                   
  The Heliographic Inertial (HGI) coordinates are Sun-centered and inertially
  fixed with respect to an  X-axis  directed along the intersection line of 
  the ecliptic and solar equatorial  planes. The solar equator plane is 
  inclined at 7.25 degrees from the ecliptic. This direction was towards 
  ecliptic longitude of 74.36 degrees  on  1  January  1900  at  1200  UT;  
  because of precession of the celestial  equator, this longitude increases 
  by 1.4 degrees/century. The Z axis  is  directed perpendicular and northward
  from the solar equator, and the  Y-axis completes the right-handed set. This
  system differs from the usual  heliographic  coordinates  (e.g. Carrington 
  longitudes) which are fixed in the frame of the rotating Sun. 
                
  The  RTN  system is fixed at  a  spacecraft  (or the planet). The R 
  axis  is  directed  radially  away  from  the Sun, the T axis is the cross 
  product  of  the solar rotation axis and the R axis, and the N axis is the 
  cross  product  of  R  and  T.  At  zero  Heliographic  Latitude  when the 
  spacecraft  is in the solar equatorial plane the N and solar rotation axes 
  are parallel.




Hour averages of the interplanetary solar wind data from, and hourly 
heliocentric coordinates of, Pioneer 10/11 and other interplanetary spacecraft
may be also be accessed and plotted on-line through the COHOWeb service
http://cohoweb.gsfc.nasa.gov/

Acknowledgement:

Use of these data in publications should be accompanied at minimum by
acknowledgements of the National Space Science Data Center, and the responsible
Principal Investigator defined in the experiment documentation provided here.
Citation of NSSDC's Coordinated Heliospheric Observations (COHO) data base
would also be appreciated, so that other potential users will be made aware of
this service. 

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