  This letter aims at deriving a Semiparametric Slepian-Bangs (SSB) formula for
Complex Elliptically Symmetric (CES) distributed data vectors. The
Semiparametric Cram\'{e}r-Rao Bound (SCRB), related to the proposed SSB
formula, provides a lower bound on the Mean Square Error (MSE) of \textit{any}
robust estimator of a parameter vector parameterizing the mean vector and the
scatter matrix of the given CES-distributed vector in the presence of an
unknown, nuisance, density generator.
