  Several planet-search groups have acquired a great deal of data in the form
of time-series spectra of several hundred nearby stars with time baselines of
over a decade. While binary star detections are generally not the goal of these
long-term monitoring efforts, the binary stars hiding in existing planet search
data are precisely the type that are too close to the primary star to detect
with imaging or interferometry techniques. We use a cross-correlation analysis
to detect the spectral lines of a new low-mass companion to $\psi^1$ Draconis
A, which has a known roughly equal-mass companion at ${\sim}680$ AU. We measure
the mass of $\psi^1$ Draconis C as $M_2 = 0.70 \pm 0.07 M_{\odot}$, with an
orbital period of ${\sim}20$ years. This technique could be used to
characterize binary companions to many stars that show large-amplitude
modulation or linear trends in radial velocity data.
