Cross-Calibration Meeting, ESTEC, February Comparison of the EDI and FGM Measurements of the Magnetic Field Magnitude Plot shown by Harri Laakso in the Cross-Calibration Kickoff Meeting Big discrepancy between the 2 measurements visible for C2

Cross-Calibration Meeting, ESTEC, February EDI 3-hourly Survey Plots are VERY useful Color convention is to use: - cyan for WW instrument mode and data - dark blue or violet for AG(=AE) instr. mode and data - black for FGM B, via onboard link. Panel 1 +2 from top show 24 h overview. Red box in panel 1 is used to highlight the 3 hours expanded in the 5 panels below. (panel 1) - raw data counts from EDI (panel 2)- instrument mode WW and AG - magnetic field magnitude from FGM, via onboard link (panel 3) - ambient electron counts (labels on right) - electron drift velocity in B_perp plane (labels on left) (panel 4) ( labels on right ) : -0 or 180 to 90 degrees anisotropy normalized -to statistical uncertainty - GSE latitude of the drift velocity (labels on left) (panel 5) - 0 to 180 degrees anisotropy (labels on right) and/or - GSE azymuth of the drift velocity (labels on left) (panel 6) FGM B magnitude (panel 7) FGM B angle to S/C spin axis (aprox Z_GSE)

Cross-Calibration Meeting, ESTEC, February In EGD processed for CAA: ERROR FOUND! Fig 1. Data produced by Hans Vaith on his computerFig 2. Overplot of HAV‘s (red) and CAA-data (green) => S/W error in „wwconv.c“, affecting data between 1-24/02/2001, when the onboard sw changed SOLUTION: Expression: var = (short)( (var & 0x07ff) << 5 ) / 32; working well on other 3 computers had to be replaced by: var &= 0x07ff; var <<= 5; var /= 32; for gcc compiler EGD (for 1-24/02/2001) REPROCESSED (V02) and REPLACED in CAA

Cross-Calibration Meeting, ESTEC, February EGD Statistics for 23/02/2001 „bad“ data C2_CP_EDI_EGD__ _V01/2.cef„good“ data FGM: 1 second averages using FGM-daily calibration were interpolated to the EDI times EDI:time-of-flight in microseconds converted to B in nT using fe = 2π m/e, where the electron mass m was corrected for relativistic effect m = m 0 + T/c 2 T = 0.5 keV

Cross-Calibration Meeting, ESTEC, February EGD Statistics for Cluster-3 „2001“- Orbits

Cross-Calibration Meeting, ESTEC, February EGD Statistics for Cluster-2 „2002“-Orbits

Cross-Calibration Meeting, ESTEC, February Conclusion Cross-calibration activities are very useful ! Thanks to Harri for calling our attention to the error ! (please don‘t forget to put the date on the plot next time)

Cross-Calibration Meeting, ESTEC, February EDI Basics (2): Measurement Techniques in WW Mode EDI uses 2 techniques in the WW mode to measure the electron drift : 1.Triangulation 2.Time-of-flight Both techniques are attempted for every analysis interval. The two results are compared to one another, and based on estimated error measurements, one will be assigned the “winner” and the other the “loser”. Both drift step results are assigned a quality flag (good/caution/bad) based on some criteria. Through triangulation, one directly determines the ‘drift-step’ vector d, which is the displacement of the electrons after one gyration. The Time-of-Flight measurement provides as a by-product the gyro-time T g that is related to the magnetic field magnitude through universal constants