  We investigate the electromagnetic transitions of the singly charmed baryons
with spin 3/2, based on a pion mean-field approach, also known as the chiral
quark-soliton model, taking into account the rotational $1/N_c$ corrections and
the effects of flavor SU(3) symmetry breaking. We examine the valence- and
sea-quark contributions to the electromagnetic transition form factors and find
that the quadrupole form factors of the sea-quark contributions dominate over
those of the valence-quark ones in the smaller $Q^2$ region, whereas the sea
quarks only provide marginal contributions to the magnetic dipole transition
form factors of the baryon sextet with spin 3/2. The effects of the flavor
SU(3) symmetry breaking are in general very small except for the forbidden
transition $\Xi_c^0\gamma\to \Xi_c^{*0}$ by $U$-spin symmetry. We also discuss
the widths of the radiative decays for the baryon sextet with spin 3/2,
comparing the present results with those from other works.
