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Know and use the statistical error information provided in the CDF files. The error associated with the inherent spectrometer counting statistics is provided in the CDF files for both the moments and for the distributions. The actual counts can be recovered from the distErr variable from C = (f/distErr)**2 with distErr from the dist CDFs.
FPI moment error
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calculations
Use of the Partial Moments Calculations
Quasi-neutrality Check
Comparison of the FPI ion and electron density moments can give some indication as to how much of the underlying plasma distribution is represented in the separate FPI, HPCA, EIS, FEEPS data files.
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Error Flag Bit 13: significant (>=20%) penetrating radiation (DIS only)
Use of the Partial Mome
Spin-periodicities – Velocity Offsets
- Compression artifacts, which can be different for Survey and Burst data products
- Imperfect spectrometer response correction tables (e.g., for signals dominating the very lowest or very highest energy channels; for data intervals very near a FPI macro change; and for data intervals for which sufficient burst calibration data was not readily available). Some of these can be addressed with time.
- Imperfect spacecraft potential or photoelectron signal correction. For some data intervals, data users will necessarily need to apply custom corrections.
- In some cases, even when the in-flight calibration tables have reduced the spin-period electron bulk velocity signal amplitude to below 50 km/s, there may appear more significant 20 s oscillations in the current density n*e*(Vi-Ve) (comparable to real current densities at the magnetopause). This is a known issue and is currently beyond the scope of our current L2 processing. If such current density oscillations are noticed, please contact the FPI team, and we will address these on a case by case basis until we are able to incorporate a correction into our routine L2 processing.
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