With Hubble Space Telescope Fine Guidance Sensor astrometry and previously published radial velocity measures we explore the exoplanetary system HD 202206 .
Our modeling results in a parallax , \pi _ { abs } = 21.96 \pm 0.12 milliseconds of arc , a mass for HD 202206Â B of \cal { M } _ { B } = 0.089 ^ { +0.007 } _ { -0.006 } \cal { M } _ { \odot } , and a mass for HD 202206Â c of \cal { M } _ { c } = 17.9 ^ { +2.9 } _ { -1.8 } \cal { M } _ { Jup } .
HD 202206Â is a nearly face-on G+M binary orbited by a brown dwarf .
The system architecture we determine supports past assertions that stability requires a 5:1 mean motion resonance ( we find a period ratio , P _ { c } / P _ { B } = 4.92 \pm 0.04 ) and coplanarity ( we find a mutual inclination , \Phi = 6 \arcdeg \pm 2 \arcdeg ) .