  The question of optical bandgap anisotropy in the monoclinic semiconductor
$\beta$-Ga2O3 was revisited by combining accurate optical absorption
measurements with theoretical analysis, performed using different advanced
computation methods. As expected, the bandgap edge of bulk $\beta$-Ga2O3 was
found to be a function of light polarization and crystal orientation, with the
lowest onset occurring at polarization in the ac crystal plane around 4.5-4.6
eV; polarization along b unambiguously shifts the onset up by 0.2 eV. The
theoretical analysis clearly indicates that the shift of the b onset is due to
a suppression of the transition matrix elements of the three top valence bands
at $\Gamma$ point.
