Extreme magnification microlensing event OGLE-2008-BLG-279: Strong limits on planetary companions to the lens star

We analyze the extreme high-magnification microlensing event OGLE-2008-BLG-279, which peaked at a maximum magnification of A ∼ 1600 on 2008 May 30. The peak of this event exhibits both finite-source effects and terrestrial parallax, from which we determine the mass of the lens, M l = 0.64 0.10 M ⊙, and its distance, Dl = 4.0 ± 0.6 kpc. We rule out Jupiter-mass planetary companions to the lens star for projected separations in the range 0.5-20 AU. More generally, we find that this event was sensitive to planets with masses as small as 0.2 M ⊕ ≃ 2 MMars with projected separations near the Einstein ring (∼3 AU). © 2009. The American Astronomical Society. All rights reserved.