Energy Spectrum of the Hydrogen Atom in a Strong Magnetic Field

We obtain the energy spectrum for the 14 lowest states of the hydrogen atom in a strong magnetic field $B$. Emphasis is placed on values of $B\ensuremath{\approx}{10}^{6}\ensuremath{-}{10}^{8}$ G, characteristic of those found in magnetic white dwarfs. Our results for the ionization energy of the ground state are significantly better than those of Cohen, Lodenquai, and Ruderman for fields $\ensuremath{\lesssim}7\ifmmode\times\else\texttimes\fi{}{10}^{11}$ G.