Below is the light curve for RT Aur. what’s going on with this blue model?
Indeed, drawing of smooth relevant approximated light curve from scattered points is not trivial task! High degree polynomial regression is not the best solution.
Sharp tooth on the top of your curve is typical for W Vir pulsators, but not for classical cepheides. So “tooth” well as “waves” are artifacts of approximation, on my modest POV.
Well, I plan to learn How to use VStar CHOICE course this year for understanding of all VStar features
Especially I hope to understand optimal approximation methods for correct color indexes calculation.