Blackbody calibration sources of high accuracy for a spaceborne infrared instrument: The Along Track Scanning Radiometer

We describe the two 140-mm-aperture simulated blackbody sources used for the on-board calibration of the Along Track Scanning Radiometer, a spaceborne thermal infrared instrument for the accurate remote sensing of sea surface temperature, in operation since 1991. The design of these spaceborne sources, which operate at approximate to -10 degrees C and approximate to +30 degrees C, allows them to meet their unprecedented accuracy goal, namely a 3 sigma uncertainty in their brightness temperature of <0.1 K for the whole mission. This performance is empirically demonstrated in the laboratory and in flight by long-term temperature readout tests, temperature uniformity measurements, and direct emissivity measurements. (C) 1996 Optical Society of America