Abstract
Pre-launch absolute calibration coefficients for the CCD/CBERS-2B sensor have been calculated from radiometric measurements performed in a satellite integration and test hall in the Chinese Academy of Space Technology (CAST) headquarters, located in Beijing, China. An illuminated integrating sphere was positioned in the test hall facilities to allow the CCD/CBERS-2B imagery of the entire sphere aperture. Calibration images were recorded and a relative calibration procedure adopted exclusively in Brazil was applied to equalize the detectors responses. Averages of digital numbers (DN) from these images were determined and correlated to their respective radiance levels in order to calculate the absolute calibration coefficients. It has been the first time these pre-launch absolute calibration coefficients have been calculated considering the Brazilian image processing criteria. Now it will be possible to compare them to those that will be calculated from vicarious calibration campaigns. This comparison will permit the CCD/CBERS-2B monitoring and the frequently data updating to the user community.
Highlights
Since 1988 China and Brazil have carried out a joint space program called China-Brazil EarthResources Satellite (CBERS), specially dedicated to environmental data assessment
The objective of this paper is to describe the CCD/China-Brazil EarthResources Satellite (CBERS)-2B pre-launch absolute calibration coefficients calculations based on data collected in the satellite integration and test hall located in
A full and deep investigation must be carried out by the Brazilian user community. This validation must include the spectral characterization of different targets, which only will be achieved by the adaptation of atmospheric correction codes for the CCD/CBERS-2B sensor configuration
Summary
Since 1988 China and Brazil have carried out a joint space program called China-Brazil Earth. The CCD/CBERS-2B sensor has the same technical characteristics of its predecessor ones onboard of CBERS-1 and CBERS-2 satellites It provides images with 113 km of swath with 20 m spatial resolution and has a lateral pointing capability of ± 32o. Emphasis will be dedicated to the Camera Electronics equipment This equipment takes the CCD signal generated in each band and converts them into video output signals through two channels in which the gain control is made. The redundancy conception has been applied at this equipment It is possible generating video output signals considering “main” and “redundant” options that must be considered in the absolute calibration coefficients calculations. The adoption of any of these combinations influences the relationship between the effective measured radiance at the top of the atmosphere and the resulting Digital Numbers (DN), i.e. it influences the CCD/CBERS-2B absolute calibration. As the band 3 signals can be transmitted by two channels, specific calibrations coefficients were determined for these two options as well
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