  The first calculation of the frequency spectrum of gravitational wave mass
quadrupole radiation for binaries on hyperbolic orbits was performed in
arXiv:1207.5359. Some shortcomings of their derivation were pointed out, but
there are still inaccuracies and supplements that we believe are worthwhile to
communicate. In this note we provide a consistent and straightforward
exposition of the frequency spectrum in the case of hyperbolic encounters and
explicitly determine the parabolic limit, which was not possible with the
previous treatments.
