Correlations between the measured parameters (m_c and ϵ_max) and f(t_0i), as observed in the D1 Monte Carlo. Each point is an average over all t_0i dates in a lunation (filled symbols) or inter-lunation period (open symbols). Circles are averaged over the full mosaic, except for the first season where CCD 3 has been singled out (red squares) due to intermittent failures. Linear fits are used in the model to describe the observed correlations.