A2.4 Magnetic Field

The magnetic field is obtained from the header record of the ULA or UAV data files. If it is missing, the UMAG files can often be obtained from KUEPAM and merged into the file with the program MAGMERGE.

If the magnetic field vector is pointing such that it will be seen by any of the sectors that are averaged for a given plane, the "azimuth" of the magnetic field in that plane is calculated, and a black dot is put there. For the full coverage channels (P5-7) the "tail" of the magnetic field will also be seen in the same plane (180° away) and a white dot is placed there. Note that the particles seen coming into the sector of the detector where the magnetic vector is located (black dot) are streaming against the field direction. Particles streaming along the field will be aligned with the direction represented by the white dots. Trapped particles will occur at 90°, halfway between the black and white dots.

Because there is overlap in the panels and in the field of view of the detectors, the magnetic field indicators can occur in more than one panel simultaneously.

In the case of an electron channel being plotted, there is no LEMS120 data, and the XY panel of the display is based solely on LEFS60 data. In this case only magnetic field values occurring in a LEFS60 sector will be plotted in this panel. Similarly, if foilfact is set to 0.0 (e.g., for plotting only the low energy P channels), the XY panel will contain data only from LEMS120, and the only magnetic field values plotted in this panel will be those in a LEMS120 sector.

For the WART detector, which measures data at 60°, three panels of the XY plane are plotted, and the magnetic field is only included if the vector occurs in a CA60 sector.

Next: Appendix 2.5 LEMS and LEFS Differences

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