SPOT CALIBRATION AT THE LA-CRAU TEST SITE (FRANCE)

In-flight calibrations of SPOT1 were performed in 1989 using a French site located in La Crau (southeastern France). A full description of the procedure is presented which includes both the characterization of the ground and of the atmosphere. To predict the radiance at the satellite level, we take into account the nonlambertian properties of the test site and the surrounding contribution. A detailed error budget is carefully conducted; the overall error of the method is around +/- 3%. The three calibrations performed are self-consistent and are in close agreement with calibration data obtained by CNES for XS2 and XS3. A discrepancy of 8% is observed for XS1 and its origin is under study.