  We report the discovery of K2-287b, a Saturn mass planet orbiting a G-dwarf
with a period of $P \approx 15$ days. First uncovered as a candidate using K2
campaign 15 data, follow-up photometry and spectroscopy were used to determine
a mass of $M_P = 0.317 \pm 0.026$ $M_J$, radius $R_P = 0.833 \pm 0.013$ $R_J$,
period $P = 14.893291 \pm 0.000025$ days and eccentricity $e = 0.476 \pm
0.026$. The host star is a metal-rich $V=11.410 \pm 0.129$ mag G dwarf for
which we estimate a mass $M_* = 1.056$ $M_\odot$, radius $R_* = 1.07 \pm 0.01$
$R_\odot$, metallicity [Fe/H] = $0.20 \pm 0.05$ and $T_{eff} = 5673 \pm 75$ K.
This warm eccentric planet with a time-averaged equilibrium temperature of
$T_{eq} \approx 800$ K adds to the small sample of giant planets orbiting
nearby stars whose structure is not expected to be affected by stellar
irradiation. Follow-up studies on the K2-287 system could help in constraining
theories of migration of planets in close-in orbits.
