00readme.txt
       
This directory contains one daily-resolution file and several
hourly-resolution files containing "impact parameters" for
the three pairings of the three bodies: Earth, IMP 8, and ISEE3


The "impact parameter" is the distance by which a plasma
element moving radially away from the sun with a speed
of 390 km/s, observed at an upstream spacecraft would
miss intercepting a downstream spacecraft (or Earth),
allowing for the 30 km/s motion of the Earth and its nearby
spacecraft about the sun.

Input data were spacecraft position vectors from SSCWeb.
The algorithm used for the impact parameter (D) for the
i-j pair of bodies was

Dij = SQRT {[Yi-Yj+(Xi-Xj)/13]**2 + (Zi-Zj)**2}

The Impact Parameter for a given day in the daily file is
taken as that for the first hour of that day in the hourly file.

The format of the records (including inter-word blanks) is:

Year            I*4          1978, ...
Day of year     I*4        1...365
Hour            I*3         0...23    (not included in daily-res file)
D12             F7.1
D10             F7.1        D's are in units of earth radii
D20             F7.1        0 = EARTH, 1 = IMP8, 2 = ISEE3

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N. Papitashvili, R. Parthasarathy 
May 16, 2003