The FAST IES and EES measure 32 pitch angle directions simultaneously, 11.25° resolution, and sweep over 48 energy steps in 1/64 of a spacecraft spin. The energy range is nominally 3 eV to 25 keV for ions and 4 eV to 30 keV for electrons, respectively. Each spectrometer consists of two half sensor heads each with 180° by 10° field-of-view, FOV, that are mounted on opposite sides of the spacecraft to form a 360° planar FOV. The out-of-plane response is roughly Gaussian with a full width, half maximum, FWHM, of about 5°. The planar FOV is within the spacecraft spin plane, which is oriented with the spin vector normal to the nominal magnetic field direction. This orientation facilitates continuous pitch angle measurements. Deflectors are used to steer the sensor FOV out of this plane by up to 10° to account for variations of the magnetic field direction during the orbit. In general, the pitch angle distribution always includes both the parallel and Anti-parallel magnetic field directions. Burst data consists of a 32 angle by 48 anergy bin array of counts. Counts are pseudo-log compressed from 16 to 8 bits onboard. The first energy step is a high voltage retrace and should be ignored. Detector anodes rotate by half an anode or 5.625° each sweep. Survey data is averaged burst data that has been despun onboard. Slow survey is averaged into a 32 angle by 48 energy array each half spin or about 2.5 s. Some blurring of the angular resolution results from the half anode rotation on alternate sweeps. Fast survey is averaged into a 64 angle by 48 energy array that maintains the angular resolution. Fast survey time resolution varies from 1/16 to 1/4 of a spin.
Version:2.2.8
The FAST IES and EES measure 32 pitch angle directions simultaneously, 11.25° resolution, and sweep over 48 energy steps in 1/64 of a spacecraft spin. The energy range is nominally 3 eV to 25 keV for ions and 4 eV to 30 keV for electrons, respectively. Each spectrometer consists of two half sensor heads each with 180° by 10° field-of-view, FOV, that are mounted on opposite sides of the spacecraft to form a 360° planar FOV. The out-of-plane response is roughly Gaussian with a full width, half maximum, FWHM, of about 5°. The planar FOV is within the spacecraft spin plane, which is oriented with the spin vector normal to the nominal magnetic field direction. This orientation facilitates continuous pitch angle measurements. Deflectors are used to steer the sensor FOV out of this plane by up to 10° to account for variations of the magnetic field direction during the orbit. In general, the pitch angle distribution always includes both the parallel and Anti-parallel magnetic field directions. Burst data consists of a 32 angle by 48 anergy bin array of counts. Counts are pseudo-log compressed from 16 to 8 bits onboard. The first energy step is a high voltage retrace and should be ignored. Detector anodes rotate by half an anode or 5.625° each sweep. Survey data is averaged burst data that has been despun onboard. Slow survey is averaged into a 32 angle by 48 energy array each half spin or about 2.5 s. Some blurring of the angular resolution results from the half anode rotation on alternate sweeps. Fast survey is averaged into a 64 angle by 48 energy array that maintains the angular resolution. Fast survey time resolution varies from 1/16 to 1/4 of a spin.
| Role | Person | |
|---|---|---|
| 1. | PrincipalInvestigator | spase://SMWG/Person/James.P.McFadden |
| 2. | MetadataContact | spase://SMWG/Person/Robert.E.McGuire |
| 3. | MetadataContact | spase://SMWG/Person/Lee.Frost.Bargatze |
General Information about the FAST mission
FAST Electrostatic Analyzer Known Data Problems and Limitations
Access to Data in CDF Format via ftp from SPDF
Access to Data in CDF Format via http from SPDF
Access to ASCII, CDF, and plots via NASA/GSFC CDAWeb
CDF Epoch Time, one Element per Ion Distribution
UNIX Time, Elapsed Seconds since 1970-01-01 for each Data Record, without Leap Second Correction, one Element per Distribution, this Time is the Center Time of Data Collection
UNIX Time at the Start of Data Collection
UNIX Time at the End of Data Collection
Averaging Time, Time End minus Time Start
Integration Time, TIME_DELTA/NENERGY
Packet Header Byte Array
Validity Flag Code: Bit 0, Non-Zero Values are not necessarily Valid
Quality Flag
Number of Angular Bins
Number of Energies
Geometric Factor, used in Calibration
Geometric Factor Index
Bins Index for the Number of Angular Bins
Mode Index for the Data Mode: 0-2=Survey Data, 0-1=Burst Data
Angular Shift, converts Theta Bin Values to Pitch Angles
Angular Maximum
Angular Minimum
Background Counts
Spacecraft Potential
Burst Ion Raw Counts Array with Dimension 96⨯64⨯NUM_DISTS
Burst Ion Energy Flux Array with Dimension 96⨯64⨯NUM_DISTS, as Plasmagrams
Burst Ion Energy Flux Array with Dimension 96⨯64⨯NUM_DISTS, as Plasmagram Movies
Burst Ion Energy Flux Array with Dimension 96⨯64⨯NUM_DISTS, as Spectrograms by Energy at Sample Pitch Angle Bin Numbers of varying Pitch Angle
Burst Ion Energy Flux Array with Dimension 96⨯64⨯NUM_DISTS, as Spectrograms by Pitch Angle Bin Numbers of varying Pitch Angle at Sample Energies
Burst Ion Raw Counts Data as Audio
Median Pitch Angle
Median Energy
Energy Values for each Distribution 96⨯64⨯NUM_DISTS
Energy Bin Size for each Distribution 96⨯64⨯NUM_DISTS
Pitch Angle Values for each Distribution 96⨯64⨯NUM_DISTS
Solid Angle, Domega, for each Distribution 96⨯64⨯NUM_DISTS
Orbit Number for this File, does not Change, so only two Entries per File
Time Array, UNIX Time for Orbit Number
CDF Epoch Array for Orbit Number
Component Numbers for Energy Bin Array
Component Numbers for Pitch Angle Bin Array