  In this paper we consider output controllability for linear time-invariant
systems. In a recent paper by Danhane, Loh{\'e}ac and Jungers it has been
pointed out that although output controllability is a classical notion in
control theory, only a Kalman-type characterization was available in the
literature. In their work that authors consider time-varying linear systems. In
this short note we provide a Hautus-type characterization of output
controllability for time-invariant linear systems which is more comprehensive
and reduces to state controllability in case the output matrix is the identity
matrix.
