EXTENDED MULTIFREQUENCY OBSERVATIONS OF RADIO-EMISSION FROM THE RS CVN BINARY HR-1099

Eight 10-h sets of four-frequency data from the Australia Telescope Co mpact Array (ATCA) plus a similar quantity of Very Large Array (VLA) o bservations have been used to investigate the variations of flux densi ty and polarization of HR 1099 in time and in frequency. The data are discussed from the viewpoint of radio emission processes, Their relati on to variations in other spectral regions will be dealt with in a sub sequent paper, At the higher frequencies (5-8 GHz) the emissions are f ound to be X-mode gyrosynchrotron emission, as previously thought. At lower frequencies (1-3 GHz) narrow-band bursts of oppositely polarized emission are detected. These bursts are probably O-mode plasma emissi on. Gyrosynchrotron model fits to the radio data imply that in the non -flaring state the emission comes from a region of radius 5 x 10(9) m. It requires a highly organized magnetic field of strength ranging fro m 1 to 13 mT (10-130 G) to explain the radio data from 1.4 to 15 GHz. At times of strong flares the emitting region extends to 10(10) m. The magnetic field is tangled in the outer parts.