00readme.txt

This directory contains hourly-resolution files containing 
"impact parameters" for the seven pairings of the four bodies:
Earth, IMP 8, Wind, ACE and Geotail.

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*5          1994, ...
Day of year     I*4         1...365
Hour            I*3         0...23
Dae             F7.1
Dig             F7.1        D's are in units of earth radii
Dai             F7.1
Daw             F7.1        e,i,w,a,g = Earth, IMP, Wind, ACE, Geotail
Dge             F7.1
Die             F7.1
Dwe             F7.1
Dge             F7.1
Dgw             F7.1
Diw             F7.1

----------------------------------------------
R. Parthasarathy, N. Papitashvili, J. King
June 25, 2004