Pre-Calculated Geomagnetic Transmission Functions

For some frequently-used orbits, CREME GTRN offers pre-calculated geomagnetic transmission functions. You should use these pre-calculated transmission functions whenever possible, since they are based on a better model of Earth's magnetic field than is presently available to you if you specify the orbital parameters in GTRN yourself.

At present, these pre-calculated functions are available for two orbits:

• 51.6^o, 450 km, the Space Station orbit.
• 28.5^o, 450 km, a common orbit for Shuttle missions.

These pre-calculated functions should be used for orbits at these inclinations whenever both perigee and apogee are between 300 and 600 km.

These pre-calculated functions are averaged over all arrival directions. Directions blocked by the Earth are also properly accounted for in this averaging.

Pre-calculated functions are available for these two orbits for both quiet and stormy geomagnetic weather conditions.

Since these pre-calculated functions are orbit-averaged, the orbital segments output option is not available with them. At present, if you want to investigate segments of these orbits, you must input the orbital parameters and use calculations based on the less-accurate field model.

More information about the magnetic field models and techniques used for the pre-calculated transmission functions can be found in:

"Geomagnetic Transmission of Solar Energetic Protons during the Geomagnetic Disturbances of October 1989", by P.R. Boberg, A.J. Tylka, J.H. Adams, Jr., E.O. Flueckiger, and E. Kobel, Geophysical Research Letters, 22, 1133-1136 (1995).