BackForwardInstrument:  SIM 

Instrument details
Acronym SIM
Full name Spectral Irradiance Monitor
Purpose Spectral solar irradiance in UV/VIS/NIR/SWIR
Short description Prism spectrometer for spectral irradiance: range 0.2-2.4 μm, spectral resolution from 0.25 to 0.33 nm
Background New development for SORCE, re-flown with improvements on CSIM and part of ISS TSIS 1 and 2
Scanning Technique Sun pointing during orbital movement, data sampled every 2 min
Resolution N/A
Coverage / Cycle One measurement after integration on all data taken during the diurnal orbit arc; thus 100 min
Mass 22 kg Power 25.3 W Data Rate 4.84 kbps


Providing Agency NASA
Instrument Maturity Flown on an R&D satellite
Utilization Period: 2003 to 2022
Last update: 2021-06-23
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
  • Earth observation instrument
  • Passive optical radiometer or spectrometer
  • Solar irradiance monitor
WIGOS Subcomponents
  • Subcomponent 1
  • Absolutely calibrated broadband radiometers, and TSI and SSI radiometers
  • TSI and SSI radiometers (for solar irradiance)
Mission objectives
Primary mission objectives
  • Downward short-wave irradiance at TOA
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
Downward short-wave irradiance at TOA*5 - marginalNo specific limitation.Spectral irradiance stretching to SWIR