  We combine Spitzer and ground-based observations to measure the microlens
parallax vector ${\mathbf \pi}_{\rm E}$, and so the mass and distance of
OGLE-2014-BLG-0124L, making it the first microlensing planetary system with a
space-based parallax measurement. The planet and star have masses $m \sim
0.5\,M_{\rm jup}$ and $M\sim 0.7\,M_\odot$ and are separated by $a_\perp\sim
3.1$ AU in projection. The main source of uncertainty in all these numbers
(approximately 30%, 30%, and 20%) is the relatively poor measurement of the
Einstein radius $\theta_{\rm E}$, rather than uncertainty in $\pi_{\rm E}$,
which is measured with 2.5% precision. This compares to 22% based on OGLE data
alone, implying that the Spitzer data provide not only a substantial
improvement in the precision of the $\pi_{\rm E}$ measurement but also the
first independent test of a ground-based ${\mathbf \pi}_{\rm E}$ measurement.
