BackForwardInstrument:  PHOKA 

Instrument details
Acronym PHOKA
Full name Multi-channel ultraviolet monitor
Purpose To monitor UV solar radiation from the Sun and in the Earth's upper atmosphere
Short description Assemblage of several units to: 1) monitor UV solar radiation in the wavelengths range 1-130 nm; 2) determine the correlation between radiation in XUV/EUV band and other energy ranges; and 3) occultation measurements of UV solar radiation absorption in the Earth atmosphere at the altitudes of 150-500 km. Including Fe-XV at 28.4 nm, He-II at 30.4 nm, and H-Lyman-alpha at 121.6 nm
Background Part of a package of instruments to monitor solar activity
Scanning Technique Sun pointing from a LEO high-inclination drifting orbit. Also, Earth's limb viewing
Resolution Solar: N/A (full disk); Earth's limb: 300 km
Coverage / Cycle Full Sun disk integral at about 0.1-s rate. Also, Earth's limb during occultation
Mass Power Data Rate


Providing Agency Roscosmos
Instrument Maturity Flown on an R&D satellite
Utilization Period: 2009 to 2009
Last update: 2017-05-18
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 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 UV imager [from L1, GEO, LEO]
Mission objectives
Primary mission objectives
  • Solar EUV flux
  • Solar Lyman-alpha 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*4 - fairNo specific limitation.Few channels, moderate dynamic range
Solar Lyman-alpha flux*2 - very highNo specific limitation.H-Ly-alpha at 121.6 nm (EUV/UV boundary)