BackForwardInstrument:  RHESSI 

Instrument details
Acronym RHESSI
Full name Reuven Ramaty High Energy Solar Spectroscopic Imager
Purpose To obtain high fidelity color movies of solar flares in X-rays and gamma rays and to provide high resolution spectroscopy.
Short description Fourier Transform Spectrometer: energy range 0.003-17 MeV (soft X-rays to gamma-rays); energy resolution < 1 keV at 3 keV, increasing to ~5 keV at 5 MeV; temporal resolution 2 s for detailed image, tens of ms for basic image
Background New development
Scanning Technique Sun pointing from a low-inclination LEO. CCD array with field of view 1° (full Sun disk); angular resolution 2.3 arcsec for 3-100 keV, 7 arcsec at 400 keV, 36 arcsec above 1 MeV
Resolution 1700 km for 3-100 keV, 5000 km at 400 keV, 27000 km above 1 MeV; at Sun surface
Coverage / Cycle Full solar disk in 2 s
Mass 131 kg Power 143 W Data Rate


Providing Agency NASA
Instrument Maturity Flown on an R&D satellite
Utilization Period: 2002 to 2018
Last update: 2021-10-01
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 LEO
  • 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 X-ray imager [from L1, GEO, LEO]
Mission objectives
Primary mission objectives
  • Solar X-ray flux spectrum
  • Solar X-ray image
  • Solar gamma-ray flux spectrum
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 gamma-ray flux spectrum*2 - very highNo specific limitation.Moderate dynamic range, but associated to X-ray observation
Solar X-ray flux spectrum*1 - primaryNo specific limitation.High spectral resolution, wide dynamic range
Solar X-ray image*2 - very highNo specific limitation.Spectrometry with coarse spatial resolution