Observation of an Excited Charmed Baryon Decaying into ${\Xi }_{\mathit{c}}^0{\pi }^{+}$

Using data recorded by the CLEO II detector at the Cornell Electron Storage Ring, we report the first observation of an excited charmed baryon decaying into ${\Xi }_c^0{\pi }^{+}$. The state has mass difference $M\left({\Xi }_c^0{\pi }^{+}\right)-M\left({\Xi }_c^0\right)$ of $174.3\pm 0.5\pm 1.0\mathrm{MeV}{/c}^2$, and a width of $<3.1\mathrm{}\mathrm{MeV}{/c}^2$ (90% confidence level limit). We identify the new state as the ${\Xi }_c^{*+}$, the isospin partner of the recently discovered ${\Xi }_c^{*0\mathrm{}}$.