Analysis of the caustic events and of follow-up observational data led to the planet's discovery, which was reported in February 2011.

In a process called gravitational microlensing, the star MOA-2009-BLG-387L became a lens that created two distorted caustic images.

[1] The first caustic event was detected by the South African Astronomical Observatory (SAAO) on July 24, 2009.

The collected data from VLT and from observations during the microlensing event was run through a series of models and analyzed.

An orbiting planetary body larger than Jupiter (or of a similar size, given uncertainties) was discovered.