  While there have been nearly two dozen of spiral arms detected from
planet-forming disks in near-infrared scattered light, none of their substellar
drivers have been confirmed. By observing spiral systems in at least two epochs
spanning multiple years, and measuring the motion of the spirals, we can
distinguish the cause of the spirals, and locate the orbits of the driving
planets if they trigger the spirals. Upon a recent validation of this approach
using the co-motion between a stellar companion and a spiral, we obtained a
second epoch observation for the spiral system in the disk of V1247 Ori in the
$H$-band polarized scattered light using VLT/SPHERE/IRDIS. Combining our
observations with archival IRDIS data, we established a $4.8$ yr timeline to
constrain the V1247 Ori spiral motion. We obtained a pattern speed of
$0.40^{\circ} \pm 0.09^{\circ}$ yr$^{-1}$ for the north-east spiral. This
corresponds to an orbital period of $900\pm200$ yr, and thus the semi-major
axis of the hidden planetary driver is $118\pm19$ au for a 2.0 $\pm$ 0.1
M$_\odot$ central star. The location agrees with the gap in ALMA dust continuum
observations, providing joint support for the existence of a companion driving
the scattered-light spirals while carving a millimeter gap. With an angular
separation of 0.29" $\pm$ 0.05", this hidden companion is an ideal target for
JWST imaging.
