We report on the analysis of high microlensing event MOA-2008-BLG-379 , which has a strong microlensing anomaly at its peak , due to a massive planet with a mass ratio of q = 6.9 \times 10 ^ { -3 } .
Because the faint source star crosses the large resonant caustic , the planetary signal dominates the light curve .
This is unusual for planetary microlensing events , and as a result , the planetary nature of this light curve was not immediately noticed .
The planetary nature of the event was found when the Microlensing Observations in Astrophysics ( MOA ) Collaboration conducted a systematic study of binary microlensing events previously identified by the MOA alert system .
We have conducted a Bayesian analysis based on a standard Galactic model to estimate the physical parameters of the lens system .
This yields a host star mass of M _ { L } = 0.56 _ { -0.27 } ^ { +0.24 } M _ { \odot } orbited by a planet of mass m _ { P } = 4.1 _ { -1.9 } ^ { +1.7 } M _ { Jup } at an orbital separation of a = 3.3 _ { -1.2 } ^ { +1.7 } AU at a distance of D _ { L } = 3.3 _ { -1.2 } ^ { +1.3 } kpc .
The faint source magnitude of I _ { S } = 21.30 and relatively high lens-source relative proper motion of \mu _ { rel } = 7.6 \pm 1.6 ~ { } { mas } ~ { } { yr } ^ { -1 } implies that high angular resolution adaptive optics or \it Hubble Space Telescope observations are likely to be able to detect the source star , which would determine the masses and distance of the planet and its host star .