The photometer responds to each oscillation mode only by the integral value of the brightness distribution over the entire solar disk. This response decreases very quickly with increasing of l because all spherical harmonics are averaged over the disk. Therefore the DIFOS-M photometer working without any spatial resolution can record only modes with low l (< 3). But even in low l the oscillation spectrum is very complicated due to the frequency splitting by the solar rotation. A sophisticated frequency resolution needs continuous observation during at least two weeks. The CORONAS-F satellite will have a synchronous orbit with an altitude of 500 km and 83° inclination. This orbit permits observational periods up to 20 days without interruption by the Earth's shadow.
Spectral ranges: 6 spectral bands: 350, 500, 650, 850, 1100, 1500 nm (spectral characteristic of the photosensors, optical glass filters with a band-pass width of 10%)
Accuracy: The relative resolution of the solar flux is 10&sup-6; I&subo; for an integration time of 16 s during each measuring cycle
Visual field: 2°
Pointing accuracy: Pointing to the Sun within an accuracy of < 10' supported by the orientation system of the satellite
Orientation sensor: The photometer is additionally equipped by an orientation system with a resolution of 5"
Calibration: It is done by the sensitiveness of the photosensors in the optical bands 650 nm and 850 nm
Data output: 16 bit binary code
Temperature control: Thermostatic control of the box of photosensors within 1°
Power supply: 25 W
Mass: -- Box of photosensors: 5.1 kg -- Box of electronics: 2.8 kg
Size: -- Box of photosensors: 130 × 130 × 510 mm³ -- Box of electronics: 120 × 230 × 210 mm³