Four-colour photometry of eclipsing binaries

Complete uvby light curves of the detached Herbig Be eclipsing binary TY Coronae Australis are presented. A total of 1789 photometric measurements in each of the four colours were obtained in 1989 and in 1992-1994. A detailed analysis of the y light curve obtained in 1992-1993 is published separately (Casey et al. 1997). The reflection nebula around the system contributes about 30% of the light in all four passbands. Here we present and discuss the non-eclipse-related photometric variability of the system. We suggest that these variations are the result of variable obscuration, possibly linked to dust shells physically associated to the system