Abstract
It has been reported that the clock onboard NOAA satellite has some time errors, which lead to the geometric distortion in the track direction. The time errors have been calculated based on the PaNDA system. The results indicated that the time errors from the PaNDA were much bigger than the reported results. It seemed because the perturbation was not considered in the PaNDA system. Even though, if the time error is corrected, the geometric distortion in the track direction will decrease drastically. And the time errors will not vary rapidly in a short period. The fact of both effects on the geometric accuracy and the stableness of time errors will lead to that the geometric correction of the images with only few GCPs or without any GCPs will be able to be carried out with some accuracy.
