BackForwardInstrument:  FGM (THEMIS) 

Instrument details
Acronym FGM (THEMIS)
Full name Fluxgate Magnetometer
Purpose To measure the background magnetic field to identify and time the abrupt reconfigurations of the magnetosphere during substorm onset
Short description Device that measures the external magnetic field through the modulation induced on the magnetic field generated in a onboard two-ring coil. Dynamic range ±0.1 to ±65536 nT, resolution ±1 nT @ maximum of the dynamics
Background Part of a package of instruments to study the Magnetosphere
Scanning Technique 5 satellites moving to different positions into the Magnetosphere for 3-D field reconstruction
Resolution N/A
Coverage / Cycle Full magnetospheric volume; sampling at 0.1 s intervals
Mass 1.54 kg Power 0.85 W Data Rate


Providing Agency NASA
Instrument Maturity Flown on an R&D satellite
Utilization Period: 2007 to 2024
Last update: 2021-12-07
Detailed characteristics
Satellites this instrument is flying on

Note: a red tag indicates satellites no longer operational, a green tag indicates operational satellites, a blue tag indicates future satellites

Instrument classification
  • Solar and space environment monitors
  • Field or radiowave sensor
WIGOS Subcomponents
  • Subcomponent 2
  • Magnetospheric energetic particles and magnetometers
  • Geomagnetic field sensor [in LEO and cross magnetosphere]
Mission objectives
Primary mission objectives
  • Geomagnetic field
Evaluation of Measurements

The following list indicates which measurements can typically be retrieved from this category of instrument. To see a full Gap Analysis by Variable, click on the respective variable.

Note: table can be sorted by clicking on the column headers
Note: * Primary mission objective.
VariableRelevance for measuring this variableOperational limitationsExplanation
Geomagnetic field*1 - primaryNo specific limitation.Cluster in magnetosphere, vectorial, wide dynamics, high resolution