Data Quality and Caveats
MagEIS - data release 3 (rel03) notes (contact: Seth Claudepierre, firstname.lastname@example.org)
- Please see this document for a more detailed description of the following points.
- Detectors 0 and 1 (aka "pixels") on the six LOW/MED units (LOW-A,B; M35-A,B; M75-A,B) are known to be noisy and do not produce valid electron data.
- Detector 0 failed on MagEIS-HIGH-A on 2013/10/03. It measures ~1 MeV electrons.
- Background contamination in both MagEIS electrons and protons, due to inner zone protons and bremsstrahlung x-rays. We can correct for contamination in the MagEIS electron measurements. We cannot correct for contamination in the MagEIS proton measurements.
- There is light contamination in the MagEIS proton telescopes, when they view the sunlit Earth. This is corrected for in the level 3 data but not in the level 2 data.
- The MagEIS proton telescopes have noise in the lowest energy channels on both spacecraft, likely due to ion implant damage. The noise began around March 2013 and gets progressively worse as the mission progresses and also moves into higher energy channels.
- Major changes in electron instrument settings/performance in July-August 2013. Revised energy channel definitions and flux conversion factors, based on GEANT4 simulations and bow-tie analyses.
- MagEIS energy channels and pitch-angle bins are time-varying. Such changes were more frequent early in the mission and the energy channels have been stable since April 2013. Please see this document for a detailed history of energy channel values.
- MagEIS electron data that suffer from thermal oscillations have been removed and set to fill. This has occurred in several intervals during the mission and is due to improper functioning of the thermal control system.
- When the fluxes are low, counting statistics can produce significant errors and uncertainties.
- For a few reasons throughout the mission, some MagEIS spectrometers were operated in the “Bias Off” configuration for varying periods of time. With the bias is off, the data are not valid.
- The L2 and L3 files contain a data quality flags that the user should consult.