Optical light curves for the type IIn SN 2005ip. The connected colored filled circles represent the observational data (Stritzinger et al. 2012). The light curves exhibit a marked decrease after about +50 days, which is an indication of early dust formation. The gray curves represent fits of a theoretical model (Eq. (1)) to the light curves between +23 and +47 days. The fitting range is highlighted. The model intrinsic light curves are all clearly brighter than the observed light curves from +50 days and onward.