Instruments - AVHRR

The Sun angle is defined as the angle between the satellite-to-Sun line and the normal-to-orbital plane with the spacecraft in its operating orientation. The AVHRR/3 instrument, with the exception of the radiant cooler, operates within specification when exposed to any Sun angle from 0° to 80°. The radiant cooler operates within specification for solar angles between 0° to 68°. The spacecraft provides a Sun shield to protect the radiant cooler.

The AVHRR/3 uses an internal rotational scanning mirror that also views deep space and an internal calibration source. Those facilities (view to space and on-board black body targets) are used for the primary calibration of the IR channels (3B, 4 and 5), that occurs at each scan cycle.
 
 

Central wavelength (mm) Half power points (mm) Channel noise specifications Time availability 1 0.630 0.580 / 0.680 S/N 9:1 @ 0.5% albedo 24 hours 2 0.862 0.725 / 1.000 S/N 9:1 @ 0.5% albedo 24 hours 3a 1.1610 1.580 / 1.640 S/N 20:1 @ 0.5% albedo Day (Selectable) 3b 3.740 3.550 / 3.930 NEDT 0.12K @ 300K Night (Selectable) 4 10.800 10.300 / 11.300 NEDT 0.12K @ 300K 24 hours 5 12.000 11.500 / 12.500 NEDT 0.12K @ 300K 24 hours

 
AVHRR/3 Channel Characteristics
 
 
Last update: 28 June 2006