Abstract
In the first stage of remote sensing, it was enough that an image showed some distribution. As the technique improves high quality data have become required in order to discuss quantitatively on the change of the Earth environments, Global Warming and so on. Therefore the calibration of the radiometers on satellites becomes more important. Here is described our experience of the preflight and on-board calibration of JERS-1 OPS and Terra ASTER and that of the preflight cross-calibration of Terra and ADEOS.