File: HE2PLAHR_FMT.txt                         Version: NSSDC 11/15/2001 JFC
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HELIOS 2 INTERPLANETARY SOLAR WIND PLASMA DATA

Date Coverage: 1976-01-17 to 1980-03-04

Principal Investigator:

   Dr. Helmut R. Rosenbauer
   Max-Planck-Institut fur Aeronomie
   Postfach 20
   37191 Katlenburg, Germany
   Internet: ROSENBAUER@LINMPI.DNET.GWDG.DE
   DECnet:   ECD1::LINMPI::ROSENBAUER

Data Contacts: 

   Dr. Rainer Schwenn
   Max-Planck-Institut fur Aeronomie
   Postfach 20
   37191 Katlenburg, Germany
   Internet: SCHWENN@LINAX1.MPAE.GWDG.DE
   DECnet: ECD1::LINMPI::SCHWENN

   Prof. John W. Freeman
   Department of Space Physics
   Rice University
   PO Box 1892
   Houston, TX   77251
   Internet: FREEMAN@ALFVEN.RICE.EDU
   DECnet: RICE::FREEMAN

NSSDC Dataset ID: 76-003A-09B (Helios 2 merged field & plasma data set)

Dataset Description: 

This directory includes hourly average solar wind plasma data from the 
plasma analyzer experiment on the Helios 2 spacecraft. The data
have been extracted into ASCII format from a merged solar wind magnetic field
and plasma data set compiled at NSSDC by Prof. J. W. Freeman of Rice
University. The experiment Principal Investigator, H. R. Rosenbauer, or the
data contact, R. Schwenn, may be contacted directly (see addresses above)
regarding potential availability of other data from his experiment. 

Data Parameter Description:

 NY      - YEAR OF THE DATA INTERVAL (LAST TWO DIGITS ONLY). 
 ND      - DAY OF THE DATA INTERVAL FROM THE FIRST DAY OF THE ABOVE YEAR,  
           JAN. 1= DAY 1.  
 NH      - HOUR OF THE DAY OF THE DATA INTERVAL.                      
 SWSPD   - THE SOLAR WIND BULK FLOW SPEED (IN KM/S).  
 TPRADK  - THE RADIAL COMPONENT OF THE PROTON TEMPERATURE (IN DEGREES 
           KELVIN).
 SWPDEN  - SOLAR WIND NUMBER DENSITY (IN PROTONS/CM3).                
 PFELEV  - PROTON FLOW ELEVATION ANGLE (IN DEGREES, + IS NORTHWARD FLOW WITH
           RESPECT TO THE ECLIPTIC PLANE).
 PFAZIM  - PROTON FLOW AZIMUTH ANGLE (IN DEGREES, +-180; ZERO DEGREES IS IN
           THE DIRECTION OPPOSITE TO THE X-AXIS IN THE SPACECRAFT-CENTERED
           SOLAR ECLIPTIC [SSE] SYSTEM; AZIMUTH INCREASES POSITIVELY IN THE
           DIRECTION OF PLANETARY MOTION AROUND THE SUN, OPPOSITE TO THE
           Y-AXIS OF THE SSE SYSTEM).  

 The Spacecraft-Centered Solar Ecliptic (SSE) system is analogous to the
 Geocentric Solar Ecliptic (GSE) system, in that the X-axis points from
 the central body (the spacecraft) towards the Sun, the Z-axis is directed
 towards Ecliptic North, and the Y-axis lies in the Ecliptic and is directed
 opposite to the direction of planetary motion around the Sun. The plasma
 flow angles are measured with respect to the negative X-axis in the SSE
 system, so that zero degrees corresponds to outward radial flow in for
 both angles.

File Parameter Format:

      WRITE(20,130) NY,ND,NH,SWSPD,TPRADK,SWPDEN,PFELEV,PFAZIM
130   FORMAT(1X,I2,1X,I3,1X,I2,F8.2,2E10.3,2F7.2)

  Note 1: These plasma parameters were extracted from merged data set in directory 
  HELIOS_2/MGD_FREEMAN with code READHEL.for. 

  Note 2: Proton flow angles in this directory before 1993-03-26 were in error
  and should be recopied from the current files.

Reference: 

     H. ROSENBAUER, R. SCHWENN, E. MARSCH, B. MEYER, H. MIGGENRIEDER, 
     M. D. MONTGOMERY, K. H. MUHLHAUSER, W. PILIPP, W. VOGES AND S. 
     M. ZINK, A SURVEY ON INITIAL RESULTS OF THE HELIOS PLASMA 
     EXPERIMENT, J. GEOPHYS.,42,561-580, 1977. 


Related Information and Data:

Further details on the spacecraft, experiment, data sets at NSSDC, and related
WWW sites can be found on the Helios 1/2 flight project page under

http://nssdc.gsfc.nasa.gov/space/

Hour averages of the interplanetary solar wind data from, and hourly heliocentric
coordinates of, Helios 1/2 and other interplanetary spacecraft may be also
be accessed and plotted on-line through the COHOWeb service based at the same
WWW site as above.

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.