OPTICAL VARIABILITY OF THE LARGE MAGELLANIC CLOUD SUPERSOFT SOURCE RXJ0513.9-6951 FROM MACHO PROJECT PHOTOMETRY

Using the exceptional monitoring capabilities of the MACHO project, we present here the optical history of the LMC supersoft source (SSS) RX J0513.9 - 6951, for a continuous 3-year period, Recurring low states, in which the optical brightness drops by up to a magnitude, are obser ved at quasi-regular intervals, This provides a crucial insight into t he nature of the supersoft sources and, in particular, a chance to inv estigate the poorly understood behaviour of their accretion discs. Ana lysis of the high-state data reveals a small modulation of semi-amplit ude similar to 0.02 mag at P = 0.762 78+/-0.000 05 d, a period which i s consistent with the current 'best' suggested spectroscopic value.