  We report the detection of the orbital velocity of non-transiting hot Jupiter
Tau Boo b. By employing high-resolution ground-based spectroscopy around 2.3
{\mu}m during one half night, we are able to detect carbon monoxide absorption
lines produced in the planet atmosphere, which shift significantly in
wavelength during the course of the observations due to the orbital motion of
the planet. This detection of the planetary signal results in the determination
of the orbital inclination being i = 47 (+7, -6) degrees and furthermore allow
us to solve for the exact planetary mass being mp = 5.6 (0.7) MJup. This
clearly confirms the planetary nature of the non-transiting companion to Tau
Boo.
