BackForwardInstrument:  OLS 

Instrument details
Acronym OLS
Full name Operational Linescan Systerm
Purpose Cloud observation and day/night VIS imagery for fire detection
Short description 3-channel VIS/IR radiometer, including a day/night VIS channel implemented by a photomultiplier [see detailed characteristics below]
Background Flown on all satellites of the DMSP series
Scanning Technique Whiskbroom; 7325 pixels/line sampled cross-track for panoramic distortion correction at 0.5 km intervals. Swath 2960 km
Resolution 0.56 km. Cross-track sampling at 0.5 km intervals
Coverage / Cycle Global coverage twice/day in both VIS and TIR
Mass 25 kg Power 170 W Data Rate 266 kbps


Providing Agency DoD
Instrument Maturity Flown on operational programme
Utilization Period: 1976 to 2025
Last update: 2021-06-22
Detailed characteristics

Central wavelength

Spectral interval

SNR or NEΔT @ specified input

0.71 µm (day/night)

0.47-0.95 µm

… @ … W m-2 sr-1 µm-1

0.75 µm

0.40-1.10 µm

… @ … W m-2 sr-1 µm-1

11.7 µm

10.0-13.4 µm

… K @ 300 K

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
  • Moderate resolution optical imager
WIGOS Subcomponents
  • Subcomponent 1
  • VIS/IR imagery; realisation of a Day/Night band [in SSO]
  • VIS/IR imager [in SSO]
  • VIS/IR imager with day/night capability [in SSO]]
Mission objectives
Primary mission objectives
  • Cloud cover
  • Cloud top temperature
  • Cloud type
  • Fire fractional cover
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
Cloud cover*4 - fairNo specific limitation.VIS and TIR channels
Cloud top temperature*5 - marginalNo specific limitation.TIR window channel(s)
Cloud type*4 - fairDaylight only.VIS and TIR channels
Fire fractional cover*4 - fairCloud sensitive.. Coarse spatial resolution.VIS and TIR channels
Fire radiative power5 - marginalCloud sensitive.. Coarse spatial resolution.TIR channels
Fire temperature5 - marginalCloud sensitive.. Coarse spatial resolution.TIR channels
Photosynthetically Active Radiation (PAR)5 - marginalCloud sensitive.VIS channels, range undersampled
Sea surface temperature5 - marginalCloud sensitive.TIR window channel(s) around 11 micrometers .
Snow cover5 - marginalCloud sensitive.. Daylight only.VIS channel(s)
Soil moisture at surface4 - fairCloud sensitive.. Index only.VIS and TIR window channels. Soil moisture inferred from thermal inertia
Wind (horizontal)5 - marginalLimited to high latitudes.. Cloud or water vapour tracers needed.TIR channel(s) around 11 micrometers window
Sea-ice cover5 - marginalCloud sensitive.VIS and TIR channels