Circular Polarisation Observations of SS433

We present four epochs of observations of the Galactic X-ray binarySS433 using the Australian Telescope Compact Array (ATCA). These observations, taken on 4 February, 29 February, 23 March and 27 June 2000, at four frequencies ranging from 1–9 Ghz, are used to monitor the circular polarised emission from the source. We obtain circular polarisation spectra for the first three epochs with spectralindices α, (mc∝να), equal to 0.07±0.10, –1.07±0.09 and –0.18±0.05 and also observe a sign change in Stokes V. This change of handedness may indicate along-term restructuring of the magnetic field.