Classification of Observed Proton Pitch Angle Distributions

The instument covered the energy range between 20 eV to 40 KeV. We looked at proton distribution functions from four energy ranges, 20 eV - 100 eV, 100 eV - 1 KeV, 1 KeV - 10 KeV and 10 KeV - 40 KeV. O+, He+ and He++ ions are part of this project and are yet to be done. We classified all data according to the seven types of pitch angle distributions.

For each distribution type we observed we recorded the ephemeris information (i.e. date/time, L-parameter, local time). This way we could organize our data as how many times a certain pitch angle ditribution was observed as a function of Energy range, L-parameter and local time.

In the plots that follow the five columns correspond to the following five types: field aligned bidirectional, isotropic, normal, hat and butterfly. The four rows correspond to the four energy ranges: from top to bottom 20 eV - 100 eV, 100 eV - 1 KeV, 1 KeV - 10 KeV and 10 KeV - 40 KeV.

The satellite did not spend equal time on all L-parameter - local time regions. This resulted in more events being observed in regions where the satellite spent most of the time. Therefore we normalized the data by dividing the number of events observed in a certain L-parameter - local time bin for a certain distribution type over the total number of events (for all types) observed in this bin.


Field aligned bidirectional

Isotropic Normal

Hat and Butterfly

Proton Pitch Angle Distributions [plot]

Proton Pitch Angle Distributions (quiet time)


Proton Pitch Angle Distributions (Disturbed Time)