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Instrument: SEAWIFS : Sea-Viewing Wide Field-of-View Sensor
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Associated Platforms

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
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The SeaWiFS instrument was launched by Orbital Sciences Corporation on the OrbView-2 (a.k.a. SeaStar) satellite in August 1997, and collected data from September 1997 until the end of mission in December 2010. SeaWiFS had 8 spectral bands from 412 to 865 nm. It collected global data at 4 km resolution, and local data (limited onboard storage and direct broadcast) at 1 km. The mission and sensor were optimized for ocean color measurements, with a local noon (descending) equator crossing time orbit, fore-and-aft tilt capability, full dynamic range, and low polarization sensitivity.

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

Online Resources

Instrument Logistics
Instrument Start Date: 1997-09-01
Instrument Stop Date: 2010-12-11
Instrument Owner: USA/NASA