  We report the discovery of OGLE-2016-BLG-1190Lb, which is likely to be the
first Spitzer microlensing planet in the Galactic bulge/bar, an assignation
that can be confirmed by two epochs of high-resolution imaging of the combined
source-lens baseline object. The planet's mass M_p= 13.4+-0.9 M_J places it
right at the deuterium burning limit, i.e., the conventional boundary between
"planets" and "brown dwarfs". Its existence raises the question of whether such
objects are really "planets" (formed within the disks of their hosts) or
"failed stars" (low mass objects formed by gas fragmentation). This question
may ultimately be addressed by comparing disk and bulge/bar planets, which is a
goal of the Spitzer microlens program. The host is a G dwarf M_host =
0.89+-0.07 M_sun and the planet has a semi-major axis a~2.0 AU. We use Kepler
K2 Campaign 9 microlensing data to break the lens-mass degeneracy that
generically impacts parallax solutions from Earth-Spitzer observations alone,
which is the first successful application of this approach. The microlensing
data, derived primarily from near-continuous, ultra-dense survey observations
from OGLE, MOA, and three KMTNet telescopes, contain more orbital information
than for any previous microlensing planet, but not quite enough to accurately
specify the full orbit. However, these data do permit the first rigorous test
of microlensing orbital-motion measurements, which are typically derived from
data taken over <1% of an orbital period.

Earth and Planetary Astrophysics