  The analytic Born-Oppenheimer (B-O) potential curve for the ground state
$X^1\Sigma^+$ of the molecule (H,D,T)Cl is constructed for the whole range of
internuclear distances $R \in [0,\infty)$ with an accuracy of 3-5 figures in
comparison with the RKR-style potential curve derived from available
experimental data on vibrational energies. With an accuracy of 3-4 significant
figures in the energies, it is predicted for HCl (DCl, TCl) the 836 (1625,
2366) B-O rovibrational bound states with maximal vibrational number $\nu_{max}
= 20\, (29, 35)$ and maximal angular momentum $L_{max} = 64\, (90, 109)$
including 24 (46, 63) weakly-bound states (close to the dissociation limit)
with energies $\lesssim 10^{-4}$ Hartree. Insufficiency of existing
experimental data is indicated and a prediction of the bulk of missing
rovibrational states is made for all HCl, DCl, TCl molecules.
