LONG-TERM FLUX MONITORING OF LSI-DEGREES-303 AT 2.25 AND 8.3 GHZ(61)

LSI +61 degrees 303 is an exotic binary system consisting of a similar to 10 M-. B star and a compact object that is probably a neutron star . The system is associated with the interesting radio source GT 0236 610, which exhibits bright radio outbursts with a period of 26.5 days . We report the results of continuous daily radio interferometric obse rvations of GT 0236 + 610 at 2.25 and 8.3 GHz from 1994 January to 199 6 February. The observations cover 25 complete (and three partial) cyc les with multiple observations each day. We detect substantial cycle-t o-cycle variability of the radio emission characterized by a rapid ons et of the radio flares followed by a more gradual decrease of the emis sion. We detect a systematic change of the radio spectral index alpha (defined as S-nu proportional to nu(alpha)), which typically becomes l arger than zero at the onset of the radio outbursts. This behavior is suggestive of expansion of material initially optically thick to radio frequencies, indicating either that synchrotron or inverse Compton co oling are important or that the free-free optical depth to the source is rapidly changing. After two years of observations, we see only weak evidence for the proposed 4 year periodic modulation in the peak flux of the outbursts. We observe a secular trend in the outburst phases a ccording the best published ephemeris. This trend indicates either orb ital period evolution, or a drift in outburst orbital phase in respons e to some other change in the system.