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Instrument: SEAWIFS : Sea-Viewing Wide Field-of-View Sensor |
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Associated Platforms SEASTAR Spectral/Frequency Information Wavelength Keyword: Visible Number Channels: 6 channels Spectral/Frequency Coverage/Range: 0.4 - 0.7 micrometers Wavelength Keyword: Near Infrared Number Channels: 2 channels Spectral/Frequency Coverage/Range: 0.765 - 0.865 micrometers Related Data Sets View all records related to this instrument Description The SeaWiFS instrument has scanning mechanisms to drive an off-axis folded telescope and a rotating halfangle mirror. Incoming scene radiation is collected by the folded telescope and reflected onto the rotating half-angle mirror. The collected radiation is then relayed through dichroic beam splitters to separate the radiation into four wavelength intervals each wavelength interval encompassing two of the eight SeaWiFS spectral bands. Four corresponding aft-optics direct the radiation in the four separate wavelength intervals through two separate spectral band-pass filters that further separate the radiation into eight SeaWiFS spectral bands. The aft-optics assemblies also image each of the resultant defined bands of radiation onto four detectors that are aligned in the scan direction. Monitoring of sensor calibration over periods of a few orbits, to several months or years, is accomplished using solar calibration for the former and lunar calibration for the latter. Solar calibration uses a solar-radiation diffuser and an input port located in a fixed position outside of the 58.3 degree SeaWiFS scene-scan interval. Lunar calibration is accomplished by a spacecraft maneuver to view the moon when the spacecraft is in the nighttime portion of its orbit. Key SeaWiFS Facts Scan Width: 58.3 deg (LAC); 45.0 deg (GAC) Scan Coverage: 2,800 km (LAC); 1,500 km (GAC) Pixels along Scan: 1,285 (LAC); 248 (GAC) Nadir Resolution: 1.13 km (LAC); 4.5 km (GAC) Scan Period: 0.124 seconds Tilt: -20, 0, +20 deg Digitization: 10 bits (LAC stands for Local Area Coverage; GAC stands for Global Area Coverage) Online Resources http://oceancolor.gsfc.nasa.gov/SeaWiFS/ http://oceancolor.gsfc.nasa.gov/ Instrument Logistics Instrument Start Date: 1997-09-01 Instrument Owner: USA/NASA |
