The IR variability of SS433

We report here the results of a one-year monitoring programme of SS433 at IR and visual wavelengths. The most striking feature of these observations is the near constancy of the IR colours while the source's flux varies over a range of 1.2 mag. There is no evidence for the 13.1-day period first reported in radial-velocity measurements by Crampton et al. However, it seems possible that an 11.8-day period is present.