OMNIWeb Plus Browser
to browse data as part of data selection or to create subsetted files
Impact parameters between several objects (Earth,IMP,Wind,ACE,Geotail)

This interface provides access to hourly resolution "impact parameters" for pairs of IMP 8, Geotail, Wind, ACE and Earth. These are the distances 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. Dij, the impact parameter for the i-j pair of bodies, is given by SQRT {[Yi-Yj + (Xi-Xj)/13]**2 + (Zi-Zj)**2}.
For a schematic figure and further description click HERE.
To download data from SPDF/FTP site click HERE

IMP     1994-11-16 - 2009-12-31
Geotail 1995-08-09 - 2022-12-31
WIND    1994-11-16 - 2023-05-15
ACE     1998-02-05 - 2023-05-15
Please enter your selections and then click on the Submit button.

*Select an activity
    Plot data List data Create file (file?)

*Enter start and stop dates (Use yyyymmdd)
    Start      Stop

*Select variables
ACE-Earth, (Re)
ACE-Geotail, (Re)
ACE-Wind, Re
Geotail-Earth, Re
IMP-Earth, Re
WIND-Earth, Re
Geotail-IMP, Re
Geotail-Wind, Re
IMP-Wind, Re

*Advanced plot selections (optional)
Y-axis Scale:
Image size (pixels)X: Y: Character size(0.5-2.0)
Symbol Symbol Size(0.1-4.0):

If you have any questions/comments about the OMNIWeb+, contact: Dr. Natalia Papitashvili, Mail Code 672, NASA/Goddard Space Flight Center, Greenbelt, MD 20771

NASA Official: Robert Candey (, Head of the Space Physics Data Facility .