aareadme.txt

This data set is a 20-min-resolution collection of solar wind plasma 
parameters from the interplanetary phases of the Soviet Vega 1 and 2
missions to Comet Halley.  
The data, provided by Dr. M. Verigin of the Space Research Institute
in Moscow (verigin@iki.rssi.ru),  consist of proton flow speeds, 
densities and temperatures determined by fitting counts-vs-energy data 
measured on the sunward-looking electrostatic analyzer to a convecting
Maxwellian.  There are actually two sets of parameters, one ("linear")
obtained by minimizing the sum of squares of measured and modelled counts 
and the other ("log") used logs of counts rather than counts themselves.
Also included are numbers of energy intervals used in the linear and log 
determinations less than and greater than the spectral peaks.

The data are at 20-min resolution because during cruise phase only one or 
two 10-sec spectra were determined every 20 minutes.  Further, the data 
have long gaps between the first and last days of coverage as summarized 
here -
Time span for
Vega 1:     85/03/09 - 86/10/04
Vega 2:     85/03/09 - 86/03/27

    
The major data gaps are
             Vega 1:                     Vega 2:
        85/04/20 - 85/07/23          85/04/16 - 85/07/24    
        85/12/21 - 86/01/05          85/09/27 - 85/11/27
        86/04/29 - 86/08/04          85/12/03 - 86/02/20
                                     86/02/23 - 86/03/06

 Data Format: (6I3,I4,2F8.2,2F8.3,2E11.4,F7.0)

6I3,I4 - Year, Month, Day, Hour, Min, Sec (UT), Spacecraft ID (1 or 2)
2F8.2  - (lin,log) proton speed,        km/s
2F8.3  - (lin,log) proton density,         cm^-3
2E13.4 - (lin,log) proton temperature,     K
F7.0   - 4-digit number abcd that codes the number of ion
         energy intervals used in lin (a+b+1) or log (c+d+1)
         maxwellian fitting procedures. a,c - number of intervals
         used with energies less than energy of ion spectra maximum.
         b,d - number of intervals used with energies more
         than energy of ion spectra maximum.


Discussions of this investigation are found in Gringauz et al (Nature,
v321, p282, 1986), Galeev et al (JGR, v93, p7527, 1988) and references 
therein.
NSSDC contact person: Dr. Natalia Papitashvili (natasha@mail630.gsfc.nasa.gov)