Deployment test of the NIST EOS Thermal-infrared Transfer Radiometer

Abstract

The National Institute of Standards and Technology (NIST) Thermal-infrared Transfer Radiometer (TXR), developed for the National Aeronautics and Space Administration (NASA) Earth Observing System (EOS), was deployed at the remote sensing radiometric calibration facility at Los Alamos National Laboratory (LANL). The purpose of the deployment was to test the ability of the TXR to operate off-site of NIST in a host cryogenic vacuum chamber, and to provide an end-to-end verification of the radiance scale in the LANL facility. The TXR was calibrated pre-trip and post-trip at NIST against a water bath black body in ambient conditions. At LANL, the TXR was operated in a liquid nitrogen cooled vacuum chamber, mounted in the same position that remote sensing instruments occupy during their pre-flight calibrations. The results from the TXR 5 µm channel show that the LANL radiance scale agrees with that of the NIST water bath black body to within a radiance uncertainty of - 0.16% ( k = 2). This corresponds to a brightness temperature uncertainty of 50 mK ( k = 2) at 300 K. Thus, the TXR has demonstrated its ability to provide an economical end-to-end system-level verification of the component-level radiometric scale assigned to a calibration facility. Such verifications provide an extra level of confidence in the radiometric accuracy of flight instrument calibration facilities that has hitherto not been possible.