THEMIS-B: On Board spin fits of Electric (EFI) and Magnetic (FGM) fields. This file contains data EFI and FGM that has been despun on-board to 3 second resolution. It stores meta information like the number of points that contributed to each spin and the standard deviation of those points. For the EFI data it also stores variables with the Z component of the EFI data zeroed and the Z component of the EFI estimated using the E.B=0 equality. The need to use an estimated Z axis for the EFI is due to error in measurements from the EFI axial booms. These data are provided in DSL (despun spacecraft L-Z vector), GSM, and GSE coordinates.
Version:2.2.9
THEMIS-B: On Board spin fits of Electric (EFI) and Magnetic (FGM) fields. This file contains data EFI and FGM that has been despun on-board to 3 second resolution. It stores meta information like the number of points that contributed to each spin and the standard deviation of those points. For the EFI data it also stores variables with the Z component of the EFI data zeroed and the Z component of the EFI estimated using the E.B=0 equality. The need to use an estimated Z axis for the EFI is due to error in measurements from the EFI axial booms. These data are provided in DSL (despun spacecraft L-Z vector), GSM, and GSE coordinates.
| Role | Person | |
|---|---|---|
| 1. | PrincipalInvestigator | spase://SMWG/Person/Vassilis.Angelopoulos |
| 2. | CoInvestigator | spase://SMWG/Person/John.W.Bonnell |
| 3. | CoInvestigator | spase://SMWG/Person/Forrest.S.Mozer |
NASA/GSFC CDAWeb ftp access to the data.
In CDF via HTTP from SPDF
Access to ASCII, CDF, and plots via NASA/GSFC CDAWeb.
Fluxgate magnetometer on-board instrument measurements are at higher resolution. This parameter stores the standard deviation of the fluxgate magentometer spin fit for each spin resolution element of this data quantity in nT.
FGS (spin-fit) magnetic field vector in despun spacecraft coordinates (DSL). To despin, these data are direction corrected using the spin-model and binned down from the cadence of the instrument to the cadence of each spin (3-sec). These coordinates (DSL) use the Z axis of the spin plane (L Vector), not the probe geometric Z axis.
This structure represents the Magnetic Field Vector B in DSL
FGS (spin-fit) magnetic field vector in GSE coordinates. These data are despun. To despin, these data are direction corrected using the spin-model and binned down from the cadence of the instrument to the cadence of each spin (3-sec). Then they are converted to GSE on the ground.
This structure represents the Magnetic Field Vector B in GSE
FGS (spin-fit) magnetic field vector in GSM coordinates. These data are despun. To despin, these data are direction corrected using the spin-model and binned down from the cadence of the instrument to the cadence of each spin (3-sec). Then they are converted to GSM coordinates on the ground.
This structure represents the Magnetic Field Vector B in GSM
Dates/Times for each measurement in seconds since 01-Jan-1970 00:00:00 UTC
Electric Field Instrument on-board measurements are at higher resolution. This parameter stores the standard deviation of the electric field instrument spin fit for each spin resolution element of this data quantity in mV/m.
EFS (spin-fit) electric field vector in despun spacecraft coordinates (DSL) To despin, these data are direction corrected using the spin-model and binned down from the cadence of the instrument to the cadence of each spin (3-sec). These coordinates use the Z axis of the spin plane(L Vector), not the probe geometric Z axis.
This structure represents the Electric Field Vector E in DSL
EFS (spin-fit) electric field vector with Z=0 in despun spacecraft coordinates. (DSL) To despin, these data are direction corrected using the spin-model and binned down from the cadence of the instrument to the cadence of each spin (3-sec). Since the Z component of the electric field has large error, it has been set to zero in this data quantity. These coordinates use the Z axis of the spin plane(L Vector), not the probe geometric Z axis.
This structure represents the Electric Field Vector E in DSL with Z=0
EFS (spin-fit) electric field vector with E dot B = 0 in despun spacecraft coordinates. (DSL) To despin, these data are direction corrected using the spin-model and binned down from the cadence of the instrument to the cadence of each spin (3-sec). Since the Z component of the electric field has large error, the value of Ez that makes the dot product of E and B closest to zero is used in this data product, rather than the measured Z value. These coordinates use the Z axis of the spin plane (L Vector), not the probe geometric Z axis.
This structure represents the Electric Field Vector E in DSL with E dot B = 0
EFS (spin-fit) electric field vector in GSE coordinates. Data are first despun on-board, then converted to GSE coordinates on the ground. To despin, these data are direction corrected using the spin-model and binned down from the cadence of the instrument to the cadence of each spin (3-sec).
This structure represents the Electric Field Vector E in GSE
EFS (spin-fit) electric field vector with Z=0 in GSE coordinates. Data are first despun on-board, then converted to GSE coordinates on the ground. To despin, these data are direction corrected using the spin-model and binned down from the cadence of the instrument to the cadence of each spin (3-sec). Since the Z component of the electric field has large error, it has been set to zero in this data quantity.
This structure represents the Electric Field Vector E in GSE with Z(dsl)=0
EFS (spin-fit) electric field vector with E dot B = 0 in GSE coordinates. Data are first despun on-board, then converted to GSE coordinates on the ground. To despin, these data are direction corrected using the spin-model and binned down from the cadence of the instrument to the cadence of each spin (3-sec). Since the Z component of the electric field has large error, the value of Ez that makes the dot product of E and B closest to zero is used in this data product, rather than the measured Z value.
This structure represents the Electric Field Vector E in GSE with E dot B = 0
EFS (spin-fit) electric field vector in GSM coordinates. Data are first despun on-board, then converted to GSM coordinates on the ground. To despin, these data are direction corrected using the spin-model and binned down from the cadence of the instrument to the cadence of each spin (3-sec).
This structure represents the Electric Field Vector E in GSM
EFS (spin-fit) electric field vector with Z=0 in GSM coordinates. Data are first despun on-board, then converted to GSM coordinates on the ground. To despin, these data are direction corrected using the spin-model and binned down from the cadence of the instrument to the cadence of each spin (3-sec). Since the Z component of the electric field has large error, it has been set to zero in this data quantity.
This structure represents the Electric Field Vector E in GSM with Z(dsl)=0
EFS (spin-fit) electric field vector with E dot B = 0 in GSM coordinates. Data are first despun on-board, then converted to GSM coordinates on the ground. To despin, these data are direction corrected using the spin-model and binned down from the cadence of the instrument to the cadence of each spin (3-sec). Since the Z component of the electric field has large error, the value of Ez that makes the dot product of E and B closest to zero is used in this data product, rather than the measured Z value.
This structure represents the Electric Field Vector E in GSM with E dot B = 0
Dates/Times for each measurement in seconds since 01-Jan-1970 00:00:00 UTC
This parameter contains the calibrated fluxgate magnetometer spin model data in despun spacecraft coordinates (DSL). The spin model uses a sine-wave spin model to calculate the spin and despin. These coefficients(A,B,C), the standard deviation(Sigma), and the average value(Avg.) are provided. The equations used for the model are
F = Sum(i=1 to N)[E(t_i) - (A + B*sin(omega*t_i)+C*cos(omega*t_i))]^2 ,
delta F/delta A = Sum(i=1 to N)-2*[E(t_i) - (A + B*sin(omega*t_i) + C*cos(omega*t_i))] ,
delta F/delta B = Sum(i=1 to N)-2*[E(t_i) - (A + B*sin(omega*t_i) + C*cos(omega*t_i))]-sin(omega*t_i) ,
delta F/delta C = Sum(i=1 to N)-2*[E(t_i) - (A + B*sin(omega*t_i) + C*cos(omega*t_i))]*cos(omega*t_i) ,
Gamma = sqrt(F/(N-1))
The system of equations is solved and outliers are removed until no more outliers can be removed.This structure stores the parameters of the FGM spin fit(A,B,C), the standard deviation of the spin fit(Sigma), and the mean of the spin fit(Avg.) as Time by 5 array
Dates/Times for each measurement in seconds since 01-Jan-1970 00:00:00 UTC
This parameter contains the calibrated electric field instrument spin model data in despun spacecraft coordinates (DSL). The spin model uses a sine-wave spin model to calculate the spin and despin. These coefficients(A,B,C), the standard deviation(Sigma), and the average value(Avg.) are provided. The equations used for the model are
F = Sum(i=1 to N)[E(t_i) - (A + B*sin(omega*t_i)+C*cos(omega*t_i))]^2 ,
delta F/delta A = Sum(i=1 to N)-2*[E(t_i) - (A + B*sin(omega*t_i) + C*cos(omega*t_i))] ,
delta F/delta B = Sum(i=1 to N)-2*[E(t_i) - (A + B*sin(omega*t_i) + C*cos(omega*t_i))]-sin(omega*t_i) ,
delta F/delta C = Sum(i=1 to N)-2*[E(t_i) - (A + B*sin(omega*t_i) + C*cos(omega*t_i))]*cos(omega*t_i) ,
Gamma = sqrt(F/(N-1))
The system of equations is solved and outliers are removed until no more outliers can be removed.This structure stores the parameters of the EFI spin fit(A,B,C), the standard deviation of the spin fit(Sigma), and the mean of the spin fit(Avg.) as Time by 5 array
Dates/Times for each measurement in seconds since 01-Jan-1970 00:00:00 UTC