  The resonant break-up of $^{19}$C on protons measured at RIKEN [Phys. Lett. B
660, 320 (2008)] is analyzed in terms of a valence-core model for $^{19}$C
including possible core excitations. The analysis of the angular distribution
of a prominent peak appearing in the relative-energy spectrum could be well
described with this model and is consistent with the previous assignment of
$5/2^{+}$ for this state. Inclusion of core-excitation effects are found to be
essential to give the correct magnitude of the cross section for this state. By
contrast, the calculation assuming an inert $^{18}$C core is found to largely
underestimate the data.
