The $\mathcal{C}$-connection and the 4-dimensional Einstein spaces

We introduce a new family of operators in 4-dimensional pseudo-Riemannian manifolds with a non-vanishing Weyl scalar (non-degenerate spaces) that keep the conformal covariance of \emph{conformally covariant tensor concomitants}. A particular case that arises naturally is the $\mathcal{C}$-connection that is a Weyl connection that keeps \emph{conformal invariance}. Using the $\mathcal{C}-$connection we give a new characterization of non-degenerate spaces that are conformal to an Einstein space.