A 60-NIGHT CAMPAIGN ON DWARF NOVAE .1. PHOTOMETRIC VARIABILITY OF SU UMA AND YZ CNC

A 60-night campaign on SU UMa, YZ Cnc and some secondary targets was c arried out during 1988 December and 1989 January at the Observatorio d el Roque de Los Muchachos (the 1988 International Time Project). The a im was to study the behaviour of these dwarf novae through their outbu rst cycle. Here we present the overall light curves of the main target s, SU UMa and YZ Cnc, which show that the optical fluxes continue to d ecrease after the end of the outburst. For YZ Cnc we find that, during quiescence, orbital variability is present, which may be interpreted as modulation caused by the bright-spot region. Near the end of an out burst, a weak, sinusoidal variation is observed; we discuss the possib ility that this arises either from the secondary star or the accretion disc.