  Ultracold metastable RbCs molecules are observed in a double species MOT
through photoassociation near the Rb(5S$_{1/2}$)+Cs(6P$_{3/2}$) dissociation
limit followed by radiative stabilization. The molecules are formed in their
lowest triplet electronic state and are detected by resonant enhanced
two-photon ionization through the previously unobserved $(3)^{3}\Pi \leftarrow
a^{3}\Sigma^{+}$ band. The large rotational structure of the observed
photoassociation lines is assigned to the lowest vibrational levels of the
$0^+,0^-$ excited states correlated to the Rb(5P$_{1/2}$)+Cs(6S$_{1/2}$)
dissociation limit. This demonstrates the possibility to induce direct
photoassociation in heteronuclear alkali-metal molecules at short internuclear
distance, as pointed out in [J. Deiglmayr \textit{et al.}, Phys. Rev. Lett.
\textbf{101}, 13304 (2008)].
