BackForwardInstrument:  APT 

Instrument details
Acronym APT
Full name Automatic Picture Transmission
Purpose Cloud imagery
Short description Television camera, single VIS cannel, 108° field of view
Background First installed on TIROS-8, then on Nimbus 1 and 2, then on the operational ESSA series and the initial NOAA satellites. Designed for real-time reception in VHF at inexpensive ground stations, also mobile
Scanning Technique Snapshot taken in 8 s and then scanned by 800 lines x 800 pixels/line transmitted in real time at the rate of 240 lines/min. Swath ranging from 1200 to 2200 km, depending on the satellite orbital height
Resolution Ranging from 1.8 to 3 km, depending on the satellite orbital height
Coverage / Cycle Near-global coverage each day, in daylight
Mass Power Data Rate Analogue: 3.2 kHz base band


Providing Agency NASA
Instrument Maturity Flown on operational programme
Utilization Period: 1964 to 1976
Last update: 2017-03-26
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
  • Moderate resolution optical imager
WIGOS Subcomponents No WIGOS subcomponents have been defined.
Mission objectives
Primary mission objectives
  • Cloud 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*5 - marginalDaylight only.. Dense cloud only.VIS channel(s)
Fire fractional cover5 - marginalCloud sensitive.. Coarse spatial resolution.. Daylight only.VIS channels
Snow cover5 - marginalCloud sensitive.. Daylight only.VIS channel(s)
Sea-ice cover5 - marginalCloud sensitive.. Daylight only.VIS channel(s)