BackForwardInstrument:  SEM/XRS-EUV 

Instrument details
Full name SEM / X-Ray Sensor - Extreme Ultra-Violet Sensor
Purpose To measure disk-integrated solar X-ray and EUV fluxes
Short description Assemblage of two channels in the X-ray ranges 0.05-0.3 nm and 0.1-0.8 nm; and five channels in the EUV ranges around 10 nm, 30 nm, 60 nm, 80 nm and 126 nm [including Fe-XV at 28.4 nm, He-II at 30.4 nm and H-Lyman-alpha at 121.6 nm]
Background Part of the SEM (Space Environment Monitor) package
Scanning Technique Sun pointing from GEO
Resolution N/A (full disk)
Coverage / Cycle Full solar disk at 2 s intervals (X-ray) and 33 s (EUV)
Mass Power Data Rate


Providing Agency NOAA
Instrument Maturity Flown on operational programme
Utilization Period: 1974 to 2027
Last update: 2021-12-16
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
  • Solar activity monitor
WIGOS Subcomponents
  • Subcomponent 1
  • X-ray spectrograph on GEO orbit
  • X-ray spectrometer at GEO
  • Subcomponent 2
  • Solar magnetograph, solar EUV/X-ray imagery and EUV/X-ray irradiance, both on the Earth-Sun line and off the Earth-Sun line
  • Solar X-ray spectrometer [from L1, GEO, LEO]
  • Solar EUV spectrometer [from L1, GEO, LEO]
  • Subcomponent 3
  • UV spectral imagery (e.g. GEO, HEO, MEO, LEO)
  • X-ray spectrometer [from GEO, HEO, MEO, LEO]
  • EUV spectrometer [from GEO, HEO, MEO, LEO]
Mission objectives
Primary mission objectives
  • Solar EUV flux
  • Solar X-ray flux
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
Solar X-ray flux*3 - highNo specific limitation.Few channels, wide dynamic range
Solar EUV flux*1 - primaryNo specific limitation.Several channels, wide dynamic range