  We report the first observation of an excited singly-charm baryon OmegaC*
(css) in the radiative decay OmegaC0 Gamma, where the OmegaC0 baryon is
reconstructed in the decays to the final states Omega-pi+, Omega-pi+pi0,
Omega-pi+pi-pi+, and Cascade-K-pi+pi+. This analysis is performed using a
dataset of 230.7 fb$-1} collected by the BABAR detector at the PEP-II
asymmetric-energy B Factory at the Stanford Linear Accelerator Center. The mass
difference between the OmegaC* and the OmegaC0 baryons is measured to be 70.8
+/- 1.0 (stat) +/- 1.1 (syst) MeV/c2. We also measure the ratio of inclusive
production cross sections of OmegaC* and OmegaC0 in e+e- annihilation.
