Theoretical determination of the spectroscopic constants of ${\mathrm{CaH}}^{+}$

Fourth-order many-body perturbation-theory calculations of the spectroscopic constants of ${\mathrm{CaH}}^{+}$ are presented as an attempt to help identify possible astronomical or laboratory observations. The results for the rotational and vibrational constants are, respectively, 4.61 and 1511 ${\mathrm{cm}}^{\mathrm{-}1}$. Similar calculations are made on ${\mathrm{MgH}}^{+}$, where comparison with experimental values shows excellent agreement, indicating reliable results for ${\mathrm{CaH}}^{+}$