[en] Ratan-600 is a radiotelescope for astronomic observations in the centimeter and millimeter wavebands, intended for investigations in the field of solar, planetary, galactic and intergalactic astrophysics. Comparative data of RATAN-600 and the largest world radiotelescopes are presented, which permit to estimate very high informativeness, ultimate resolution and sensitivity of RATAN-600. The possibility is shown to use RATAN-600 in investigations of a broad range of solar phenomena, planets and their satellites. Radiations from four Jupiter satellites have been studied. Records of 3.9 cm radiation from the Galilean satellites of Jupiter, and a Callisto brightness temperature curve showing the exact agreement between the radio-brightness temperatures measured by RATAN-600 and infra-red measurements by the Pioneer-11 space probe are presented. The observations of the nucleus of our Galaxy, its structure and radiation are preliminaryly estimated. The investigation of a unique, high-luminosity point object of unknown origin in our Galaxy is described. The Galaxy origination problem is discussed and the relict radiation range is experimentally checked. The observations are graphically compared with the calculated relict radiation brightness fluctuations