A radar system including an observation device that is mounted on a moving object, such as a satellite, and observes a target and a data processing device, installed in a data receiving facility such as a ground station, a ship or a plane, that processes data from the observation device, wherein said observation device comprises: a transmitter and receiver (11, 14) that emits a predetermined radar wave to outside said radar system, and that receives said radar wave scattered by the target and acquires a received signal; a temporary image generator (15; 15b) that temporarily carries out an azimuth compression process on the received signal acquired by said transmitter and receiver by using temporary orbit data about the moving object to generate a temporary image being a low resolution image; a data compressor that performs a data compression process on the temporary image from the temporary image generator (15, 15b) and generates compressed image data; and a data transmitter that transmits the compressed image data from the data compressor to the remote data processing device and wherein said data processing device comprises: a data receiver that receives the compressed image data transmitted by said data transmitter; a data decompressor that decompresses the compressed image data from the data receiver to acquire the original temporary image; a data reconstruction unit that carries out a process inverse to the azimuth compression process on the received temporary image to temporarily return the temporary image to a signal on which no azimuth compression is performed, and outputs the signal; and an image generator that carries out an azimuth compression process on the signal received from said data reconstruction unit to generate an image by using orbit data about the moving object having a higher degree of accuracy than said temporary orbit data about the moving object. a transmitter and receiver (11, 14) that emits a predetermined radar wave to outside said radar system, and that receives said radar wave scattered by the target and acquires a received signal; a temporary image generator (15; 15b) that temporarily carries out an azimuth compression process on the received signal acquired by said transmitter and receiver by using temporary orbit data about the moving object to generate a temporary image being a low resolution image; a data compressor that performs a data compression process on the temporary image from the temporary image generator (15, 15b) and generates compressed image data; and a data transmitter that transmits the compressed image data from the data compressor to the remote data processing device and wherein said data processing device comprises: a data receiver that receives the compressed image data transmitted by said data transmitter; a data decompressor that decompresses the compressed image data from the data receiver to acquire the original temporary image; a data reconstruction unit that carries out a process inverse to the azimuth compression process on the received temporary image to temporarily return the temporary image to a signal on which no azimuth compression is performed, and outputs the signal; and an image generator that carries out an azimuth compression process on the signal received from said data reconstruction unit to generate an image by using orbit data about the moving object having a higher degree of accuracy than said temporary orbit data about the moving object. a data receiver that receives the compressed image data transmitted by said data transmitter; a data decompressor that decompresses the compressed image data from the data receiver to acquire the original temporary image; a data reconstruction unit that carries out a process inverse to the azimuth compression process on the received temporary image to temporarily return the temporary image to a signal on which no azimuth compression is performed, and outputs the signal; and an image generator that carries out an azimuth compression process on the signal received from said data reconstruction unit to generate an image by using orbit data about the moving object having a higher degree of accuracy than said temporary orbit data about the moving object.